WORLD TRADE  
ORGANIZATION  WT/DS367/11 
9 August 2010 
 
 (10-4164) 
 Original:   English 
  
 
AUSTRALIA – MEASURES AFFECTING THE IMPORTATION OF APPLES 
FROM NEW ZEALAND 
 
Replies from the scientific experts to questions posed by the Panel
∗ 
 
  In accordance with the Procedures for the Panel' s meeting with the experts and Parties and the 
Panel's second substantive meeting, adopted by the Panel on 11 June 2009, the list of replies from the 
scientific experts to questions posed by the Pa nel will only be available in electronic format. 
 
_______________ 
 
 
                                                     
 
∗ The List of replies from the scientific experts to questions posed by the Panel is initially available in 
its original language.  A translation to French an d Spanish will follow when resources become available  WT/DS367/11 
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  ANNEX B-1 
 
 
I. GUIDELINES FOR EXPERTS 
Guideline (a)  
 
You may familiarise yourself with the case by getting an overview of the issues at hand and the 
scientific arguments and materials provided by the Parties.  Relevant ba ckground documents include 
the Parties' submissions, statements and responses to th e questions posed by the Panel, as well as the 
exhibits attached to these.  To get an overview of  the scientific materials provided by the Parties, 
please check the summary exhibit tabl es in the relevant submissions.  Australia's Final Import Risk 
Analysis Report for Apples from New Zealand is ava ilable in Exhibits AUS-1, AUS-2 and AUS-3, and 
in part in Exhibit NZ-1.  A good understanding of all of  these materials is essentia l.  To facilitate your 
work, the Panel has included, at the end of every qu estion, an indicative list of references to relevant 
parts of Parties' submissions, replies and exhibits.  This list is not exhaustive and the Parties may 
have included other information in their submission s, which they consider relevant.  If you have any 
questions regarding the background documents, pl ease contact the Panel Secretary, Serra Ayral 
(serra.ayral@wto.org). 
 
Guideline (b)  
 
As explained in the "request for experts" letter sent to you by the WTO, the questions relate to the 
following four issues: Erwinia amylovora (fire blight), including its potential spread through trade in apples and the phytosanitary measures to be applied to control its spread; Neonectria galligena (European canker), including it s potential spread through trade in apples, the 
climatic conditions for its establishment, and the phy tosanitary measures to be  applied to control its 
spread; Dasineura mali (apple leafcurling midge), includi ng its potential spread through trade in apples and 
the phytosanitary measures to be ap plied to control its spread;  and 
Pest risk assessment, including the use of semi-quantitative methodologies.  
 
Guideline (c)
 
 
In drafting your replies, please answer only those qu estions that you feel competent to answer.  
Please provide citations and references to the scientific evidence and literature on which you base 
your answers. 
 
Guideline (d)  
 
The list of questions starts with some general,  introductory questions.  The other questions are 
organized according to the relevant pests (i.e., fi re blight, European canker and apple leafcurling 
midge).  Some questions on risk assessment are separated into a special part at the end of this 
document;  some other questions also related to  risk assessment are liste d under the relevant pests 
and marked with an asterisk. 
 
Guideline (e)  
 
The questions are numbered consecu tively throughout this document.  Please identify the number of 
the relevant question in your response. 
 WT/DS367/11 
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  Guideline (f)
 
 
Please remember that the three panellists serving on the case have limited background in the specific 
scientific issues raised in this dis pute, and need your help to dig est the extensive scientific material 
submitted by the Parties.  Therefore, please provide y our answers, to the extent possible, in terms that 
are concise and may be understood by non-experts, in  order to better clarify the issues at hand and 
assist the Panel in reaching its legal findings. 
 
Guideline (g)  
 
New Zealand contests the conclusions of various steps in Australia's Final Import Risk Analysis Report for Apples from New Zealand, as indicated or referenced below.  The Panel will need the 
experts' assistance in order to: Identify and elaborate on the scientific basis upon which the challenged measures contained in 
Australia's IRA were adopted.  When referring to scien tific sources that are not contained in the IRA, 
please explain how do those relate to the scientific s ources that are contained in the IRA or to the 
measures identified in the IRA; Determine whether the relevant analysis in Au stralia's IRA is based on respected and qualified 
scientific sources, in terms of both the author(s) of, and the arguments made in , such sources (Please 
note that the scientific basis relied upon by the IRA n eed not reflect the majority view within the 
scientific community but may reflect divergent or minority views as long as it has the necessary 
scientific and methodological rigour to be considered reputable science.); 
Determine whether the reasoning articulated by th e IRA on the basis of such scientific evidence, 
including the methodologies applied, is objec tive and coherent, and whether the particular 
conclusions in the IRA find sufficient sup port in the scientific evidence relied upon; and 
Determine whether the results of  the IRA's assessment sufficiently warrant the challenged measures.  
 Dr Latorre
: 
 1. Australia's measures contained in the Import Ri sk Analysis (IRA were based on the biology 
of N. Galligena  and on current knowledge of the epidemiolo gy of European canker on apple.  The 
scientific information is discussed in AUS-2BA (p .117).  According to the Australian government, 
there is a risk that N. Galligena  will enter the country on asymptom atic mature fruits.  These fruits 
may be infected in the orchard, remaining asymptoma tic (latently infected fruits) for several weeks in 
cold storage.  This conclusion has been based  on by previous reports from France and the 
United Kingdom (Bondoux and Bulit, 1959; Swinburn e, 1975; McDonnell, 1970), indicating that a 
proportion of apparently healthy fruits develop sy mptoms after cold storage.  The phenomenon has 
also been observed in other apple-producing countries , in fruits from infected orchards in areas with 
frequent summer rains. 
2. Therefore, there is a risk of the entrance of N. Galligena  associated with asymptomatic 
(= symptomless) fruits carrying latent infection.  However, latent infections would be extremely 
unlikely in apples from orchards free of European canker in the absence of summer rains.  Under 
these circumstances, the risk of latent infection is cl ose to zero (in practice zero).  Fruits with latent 
infection cannot be differentiated from healthy fruits at harvest. 
3. The IRA conducted by Australia was performed in accordance with today's concepts and 
knowledge of plant diseases.  As stated in AUS-2 BA  (p. 40), risk is a function of the likelihoods of 
an event occurring (entrance, establishment and sp read) and the consequences or impact resulting 
from the occurrence of such biological events.  Ther efore, there is no criticism, in qualitative terms, 
with regard to the Risk Estimation Matrix presen ted in Tables 1 and 11 (AUS-2 BA, p.4 and p.41, 
respectively), where the appropriate level of  phytosanitary protection (ALOP) was set at very low 
risk (but not zero).  WT/DS367/11 
 Page 5 
 
 
  4. However, there is no scientific evidence substa ntiating the probability intervals and midpoints 
used for the semiquantitative analys is described in Table 12 (AUS-2 BA, p. 43).  Comment:  (i) Using 
midpoints (averages of wide likelihood ranges) te nds to overestimate the occurrence of a given 
biological event.  (ii) It is difficult to accept that a midpoint probability of 0.175 would be equal to low risk (Table 12);  indeed, this is a very hi gh probability for any biological event associated with 
N. Galligena .  (iii) If negligible is defined as a probability varying between 0 and 10
-6, using the 
midpoint 5 x 10-7 appears to overestimate the likelihood of all biological events approaching zero, 
particularly if such an event h as a remote possibility of occurring. 
5. Therefore the overall probability of entr ance, establishment and spread of N. Galligena  was 
7.0 x 10-2, which was rated as low (Table 37, AUS-2 BA p. 150).  Indeed, this a very high, rather than 
low, probability for any biological event associated with N. Galligena .  If this likelihood value is true, 
and assuming that market penetration in Australia is equal to 50,000,000 a pples annually (AUS-2 BA, 
p. 19), N. Galligena  should be present in 3,500,000 apples (7 %) annually, which is non-credible.  
Therefore, the overall probability (7.0 x 10-2) should be validated before acceptance.  Data validating 
the probability values given in Table 12 were not presented. 
6. Nevertheless, assuming that there is a risk (per haps negligible, but di fferent from zero) of 
entrance, establishment and spread of N. Galligena  in Australia on mature asymptomatic apples 
imported from New Zealand, the following phytosan itary measure appears reasonable for mitigating 
the risk of entrance: 
"The requirement that apples be sour ced from export orchards/blocks free of 
European canker (pest-free places of production)." 
7. Other proposed measures appear to be auxiliary (ancillary) or unnecessary. 
Guideline (h)  
 
Wherever applicable, please formulate your response with  regard to "mature apple fruit free of trash, 
either packed or sorted and graded bulk from New Ze aland" (IRA, Part B, p. 9), and indicate whether 
your response would be any different in the context of (i) "mature, symptomless apples" from 
New Zealand (New Zealand's First Written Submission,  para. 3.44) or (ii) "apples imported from 
New Zealand" to Australia in general (WT/DS367/5).  For questions relating to apples from a specific 
WTO Member other than New Zealand, please sim ilarly provide separate responses with regard to 
(i) mature apple fruit free of trash, either packed or sorted and graded bulk;  (ii) mature, symptomless 
apples;  and (iii) apples in general. 
 
Guideline (i)  
 
Where applicable, please specify whether there has been any development in the relevant science 
subsequent to the time of adoption of the IRA in November 2006, and if so, please explain. 
 
Guideline (j)  
 
The following abbreviations are used in this document: ALCM – apple leafcurling midge; ALOP – appropriate level of sanitary or phytosanitary protection; 
AQIS – Australian Quarantine and Inspection Service; 
FWS – First Written Submission to the Panel of a Party to the dispute; IRA – Australia's Final Import Risk Analysis Report for Apples from New Zealand (November 2006); 
ISPM – International Standards for Phytosanitary Measures; Opening statement – opening statement at the Panel's first substantive meeting; WT/DS367/11 
Page 6  
 
  R – response by Parties to questions posed by the Panel. 
 
Guideline (k)
 
 
The deadline for providing your replies is Monday, 23 February 2009.1 
 
_______________ 
 
 
I. INTRODUCTORY QUESTIONS 
Question 1 
Is there a commonly accepted definition or criterion  (biological, physiological, commercial, etc.) for 
determining if an apple fruit is mature?  Is there a distinction between physiological and commercial 
maturity? 
 Dr Deckers
: 
 8. Yes, the final picking date is determined by the evolution of different fruit maturity factors 
like starch degradation in the fruits, fruit firmness, fruit colour (red colour formation or the green 
background colour development) and the soluble solids  (Brix).  These different parameters are related 
to each other and should reach at the beginning of  harvest specific and variety dependent values.  
These values can be put into a formula in order to calculate the so called maturity index or Streif 
index where the formula is F/(R*S).  For each variet y there is a maturity index on which the harvest 
would start and a maturity index at which the ha rvest would end.  Fruits are harvested in the 
preclimacteric phase and in fact fruits are mostly harvested as immature fruits that still have a good 
storage capacity.  The fruits should be ripe at the time of the final consumption with a full 
development of the flavour at fruit maturity. 
Dr Latorre
: 
 9. Physiologically, apple fruits are mature (physiol ogical maturity) at the stage of development 
when fruits will continue ontogeny even if detached .  Commercial maturity indicates the stage when 
fruits have developed all their qualities (attributes) a nd are ready to eat.  Therefore physiological and 
commercial maturity are not synonyms. 
10. Yes, there is an accepted criterion to determin e apple maturity, which can be determined on 
the basis of starch content, firmness, juice sugar a nd acid content, seed color, flesh color, background 
color, and internal ethylene concentration.  For th e best storage results, apples must be harvested at 
their physiological maturity, just before the onset  of the climacteric rise (commercial maturity).  
Although the best way to determine the optimal harves t period is by monitoring the respiration rate, in 
practice, this is estimated by the starch conten t (iodine index), background color, solid solubles, 
and/or firmness.  These maturity indices have been ad justed to reflect the particularities of the main 
apple cultivars.  In addition, days after full bloo m can be used as a general guide to estimate fruit 
maturity. 
Dr Paulin
: 
 
11. There are several  accepted definitions and criteria for de termining if an apple is mature.  
Several simple tests exist (such as starch hydrolysis, as detected on halves of fruit by the iodine 
                                                      
1 As a result of the amendments to the timetable made by the Panel on 2 February 2009, the deadline 
given to experts to provide their written replies to questions was extended to 9 March.  WT/DS367/11 
 Page 7 
 
 
  reaction, which allows the determination of a matu rity stage).  Maturity itself can be defined in 
relation with cropping-time (to determine when a fruit is  best picked up), or with trade (when the fruit 
can be best shipped and sold), organoleptic (when th e fruits are at their optimal eating quality).  All 
these correspond to different stages of physiological  maturity.  Usually, for apple, the commercial 
maturity occurs before the optimal physiological matu rity (stage where the fruit is at its best flavour 
and taste quality, before decaying). 
Dr Schrader : 
 12. A commonly accepted definition or criterion for determ ining if an apple fruit is mature is the 
Streifindex.  According to this method developed by Dr Streif, the degradation of starch (determined 
with Lugol's solution), the firmness of fruit flesh a nd the content of sugar is combined ([firmness/ 
(percentage soluble solids concentration x starch index)].  The practical utility of the Streifindex 
method lies in the ease with which apple fruit maturity  at harvest can be evaluated for its suitability 
for long-term storage (e.g. Delong, J. M., Prange, R. K., Harrison, P. A., Schofield, R. A., Deell, J. R, 
1999, "Using the Streif Index as a final harvest wind ow for controlled-atmosphere storage of apples", 
Hort Science  34 (7), pp. 1171-1191 (26 ref.), pp. 1251-1255). 
13. The table below lists values of firmness, suga r content, degradation of starch and the 
Streifindex for the orientation for harvest for differe nt apple varieties (table from Höhn, E., Dätwyler, 
D., Gasser, F., Jampen, M. (1999) "Streifindex und optimaler Pflückzeitpunkt von Tafelkernobst, 
Schweiz" Z. Obst-Weinbau  (18/99), pp. 443 – 446). WT/DS367/11 
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Dr Swinburne : 
 14. The term "mature fruit" used in the context of both FWS appears to refer to the stage at which 
fruit is ready to be picked, not to any subsequent ripening process. 
15. The physiological processes involved in th e ripening of fruit such as apple are well 
understood and consist of a number of stages, begi nning with the appropriate time to harvest.  The 
optimum time of picking is generally judged to be  when the fruit have achieved maximum colour and 
can be readily detached (abscission layer formation) , perhaps augmented by using an iodine test to 
ascertain when starch has largely di sappeared (converted to sugar).  Fr uit at this stage can be referred 
to as "mature", however with many cultivars this  would not be commensurate with optimum eating 
quality as the ripening process woul d still be incomplete.  Moreover, fruit of many cultivars at this 
stage retain a measure of resistan ce to fungi responsible for rotting. 
16. Apples, along with other fruit such as ba nana, undergo major changes post-harvest, 
characterised by the onset of an increase in respiration (the climacteric), triggered by the production 
of the hormone ethylene in the form of a diffusibl e gas.  At this time cell walls start to become 
softened, the levels of soluble sugars increases whilst those of acids decrease.  Volatile compounds  WT/DS367/11 
 Page 9 
 
 
  associated with flavour are at their highest levels following the climacteric.  This is the optimum stage 
for eating (ripe), both for flavour and texture, but pe rhaps rarely achieved in commerce.  The onset of 
the climacteric can also herald an increase in susceptibility to rotting by a number of fungal 
pathogens, including N. Galligena . 
17. In the following stage respiration rates steadily  diminish and wall softening continues leading 
to loss of texture.  Acids and volatiles also decline,  adversely affecting flavour and the fruits lapse into 
senescence (over-ripe) and become unmarketable.  Fr uit frequently reaches this later stage in the 
domestic environment (i.e. after retail sale). 
18. Post harvest technologies are designed to extend the marketing period of fruit.  Of these the 
most obvious is cold storage, which reduces respir ation rates at all stages.  More sophisticated 
methods have in addition the aim of reducing the av ailability of oxygen within the store, either by 
simply sealing the chamber to exhaust supply, or by  flushing with nitrogen.  These affect both pre- 
and post climacteric changes.  Scrubbing the atmo sphere of ethylene delays the onset of the 
climacteric.  The degree of sophistication applied to store conditions is usually in accordance with 
plans for marketing, the most complex being reserved for the longest held. 
19. In commerce fruit is usually sent to market in a continuous stream following harvest, subject 
to quality controls imposed by either the buyer (e.g . supermarket chains), and/or the producer.  This 
will involve storage periods of varying length.  Thus  it is to be expected that fruit shipped from New 
Zealand to Australia would span the physiological stages outlined above from harvestable maturity up 
to the point where the eating quality drops below the demands of the consumer. 
Question 2 
Do the requirements established by Pipfruit New Zeal and (Exhibit NZ-93) in regard to maturity and 
absence of damage correspond to a commonly accepted definition or criterion?  (IRA, Part B, pp. 63 
and 315) 
 
Dr Deckers : 
 
20. Yes, this is a standard method of matu rity and fruit quality determination. 
Dr Latorre : 
 21. Yes, the requirements established by Pipfru it New Zealand with regard to maturity and 
absence of fruit damage are acceptable. 
Dr Paulin
: 
 22. Yes. This requirement corresponds to a high st andard of quality.  The specifications for 
absence of damage are of a proper level of precisi on to guarantee "symptomless  fruits" (black spots, 
rots...:  nil allowance). 
Dr Schrader
: 
 23. With regard to the requirements for maturity, th e inclusion of background colour and ethylene 
content as established by Pipfruit New Zealand goes beyond the requirements asked by the 
Streifindex.  Regarding absence of damage, class 1 as  defined in Exhibit NZ-93 is more detailed than 
e.g. quality standards required by the European Un ion, where trade class 1 refers to good quality, 
slight shape and development defects, slight col ouring defects, only slightest bruises, sufficient 
firmness. WT/DS367/11 
Page 10  
 
  Dr Swinburne
: 
 24. Pipfruit New Zealand exhibit NZ-93 outlines th e measures normally taken to ensure the 
maintenance of quality standards in apple cultivar s generally.  One would normally expect to see 
more detailed information with respect to individual  cultivars, perhaps these are in the appendices etc.  
These would refer to tolerance limits for size, shap e, colour and other attributes such as bruising and 
even the frequency of lenticels. 
Question 3 
Based on the parties' arguments, is there any d ifference between on the one hand, "class 1 export 
quality apples" and, on the other hand, "mature apple fr uit free of trash" or "mature, symptomless 
apples"?  Even if these three notions correspond to each  other, is there a risk that "class 1 export 
quality apples" exported from New Zealand might not always be mature, symptomless or free of 
trash?  (R 1-6 by the Parties) 
 
Dr Deckers
: 
 
25. Class 1 export quality apples are mature appl e fruit free of trash and the notion mature 
symptomless apples corresponds in fact to the same .  In the frame of this discussion I think it is 
important to stick on one definition like "mature apple fruit free of trash".  It is important that the 
fruits are free of trash, because the trash could harbour disease like Erwinia bacteria from infected 
orchards.  Fruits packed retail-ready can be cons idered automatically free of trash, but apple fruits 
prepared bulk in bins are not always free of trash. 
Dr Latorre : 
 26. Class 1 export-quality apples = Mature apple fruits, harvested at physiological maturity, that 
comply with the specification established for Class 1, e.g., as indicated in Exhibit NZ-93. 
27. Mature apple fruit, free of trash = apples harvest ed at physiological maturity, free of leaves, 
stems, other plant organs or junk materials that  eventually can contaminate fruits at harvest. 
28. Mature symptomless apples = apples that are visually (externally) healthy (asymptomatic) and 
have been harvested at physiological maturity, estim ated by the use of one or more maturity indices. 
29. Following the technical protocol as indicated in E xhibit NZ-93, there is no risk that "Class 1 
export-quality apples" exported from New Zealand w ill not always be mature, asymptomatic and free 
of trash. 
Dr Paulin
: 
 30. The category "class 1 export quality apple", as defined in the NZ 93 includes in its definition 
"mature apple fruits free of trash".  Trashes are not specifically mentioned in NZ description:  it is 
considered standard that, at this stage, no trash es are to be found associated with shipped apples.  
Again, "mature symptomless apples", are included in the category "class 1 export quality apples" which describes safely apples for export to Australia:  it exclude
s fruits with symptoms (whatever 
they are), immature fruits, and trashes.  These last items are not supposed to be exported under this 
category. 
Dr Swinburne : 
 
31. It is difficult to discern any meaningful differe nce between the various terms applied to the 
quality of fruit that would be exported from New Zealand.  The criteria for "maturity" quoted are  WT/DS367/11 
 Page 11 
 
 
  seemingly used to determine harvest dates; thus fruit harvested within the acceptable limits of those 
dates would be "mature" (see Q1).  Class 1 fruit, which seems to be synonymous with export quality, 
must then refer to "mature" harvested apples whic h have been subject to inspection and grading for 
blemishes (including rot symptoms) and other factors su ch as size and colour to the standard required. 
Trash is usually removed, and indeed eliminated at this stage. 
Question 4 
Based on the relevant parts of Australia's IRA, and Parties' arguments, what is your understanding as 
to the exact level of involvement of AQIS in audits  and inspections required by Australia in regard to 
fire blight, European canker and ALCM?  (IRA, Part B, pp. 314-315;  R 45-52 by the Parties) 
 Dr Deckers
: 
 32. The involvement of AQIS in audits and inspecti ons should be based on mutual respect of the 
existing quality assurance procedures in New Zealand in  the different fields like in the production at 
orchard level, the preparation of the fruits in the packing house and the exportation of the fruits.  This 
counts for the 3 diseases EA,NG and ALCM. 
Dr Latorre
: 
 33. In agreement with the plant quarantine authoriti es of New Zealand, the Australian Quarantine 
and Inspection Service (AQIS) has the right to inspect and/or audit protocols and phytosanitary 
procedures to certify a pest-free area, pest-free place of production or pest-fre e production site, with 
regard to European canker, fire blight and AL CM.  Inspection or auditing should focus on those 
aspects concerning the abovementioned pest and diseases.   There is no reason to inspect and/or audit 
other steps of the apple producti on in New Zealand unless they are directly related to these sanitation 
problems. 
Dr Paulin
: 
 
34. According to IRA it seems that Australia wants that AQIS agents be directly involved in 
audits of procedures used in the field as well as in  the packing houses, with respect with the three 
pests.  My understanding is that there is a request  from Australia that AQIS staff be involved in these 
audits.  But direct inspection  by AQIS agents is not on the agenda. 
35. The pre-clearance steps, on the contrary, accordi ng to IRA, must imply an active inspection of 
orchards by AQIS agents, as well as of fruits in the packing houses, in addition to audits of other 
arrangements.  I could not decide from the documen ts whether involvement of AQIS agents is meant 
for AQIS agents alone, or in cooperation with New Zealand officers. 
36. May be I could just add that it is not exaggerate d from Australia, at least in the first trade, to 
be willing to obtain the best possible view on the wa y the proposed measures are applied at the field 
and packinghouse levels.  Even if as I understand,  AQIS usually behaves in a more confident way 
towards other imports from New Zealand. 
Question 5 
Based on the relevant parts of Australia's IRA, and Parties' arguments, what is your understanding as 
to whether Australia requires a syst ems audit of 100% of survey teams in the field in the first year and 
100% of all packing houses, as New Zealand argues in R 46?  How would this requirement compare 
with those applied by other Members facing similar risks and situations?  (R 45-46 and 52 by the 
Parties)  WT/DS367/11 
Page 12  
 
  Dr Deckers
: 
 37. A systems audit should not mean an audit for 100% survey of the teams in the field in the first 
year and for 100% of all the packing houses involved.   Australia should clarify its exact intentions 
more transparently in this field.  An audit of the different existing quality systems at the different 
levels by AQIS looks normal. 
Dr Latorre
: 
 38. I am not in a position to give a definitive answ er to this question, except to say that both 
countries must develop a consensus protocol and that, at least during the first year, the level of 
inspection and/or audit should be in accordance with the level of disease prevalence and severity 
existing in each apple production area. 
Dr Paulin
: 
 39. My understanding is that Australia intends to a udit with standard audit techniques each survey 
team and all the packing houses, on the first year of trade. 
40. I just do not know how this compares with requirements of other members in similar 
situations. 
Dr Schrader
: 
 41. In accordance with Australia's reply to questi on 52, a 100% audit of survey teams suggests 
that auditors will apply auditing techniques, "qu estioning, listening, observation, documentation", to 
each and every member of each of the survey teams.   By contrast, the statement that "[t]he audit 
would include 100% of survey teams" signals Australia's intention to audit each survey team by applying audit techniques, "questioning, listeni ng, observation, documentation", to sufficient 
members of each team to satisfy th e auditors that the team is meeting the requirements outlined in the 
Final IRA Report.  This clarifies that Australia  intends to audit each survey team, but not each 
member in each survey team.  However, the amount of members of the survey team being audited is 
not quantified – Australia only states that "suffici ent members of each team…" will be audited.  
Therefore, in an extreme scenario, Australia could conc lude, that the team has to be audited in total as 
it would otherwise not be sufficient.  With other wo rds, no limits for members of survey teams to be 
audited are set;  "sufficient" is an arbitrary term and quite vague. 
42. In addition, I see a discrepancy in the clarifi cation of 100% audits of survey teams and the 
explanation, what 100 % of packing houses means.  The explanation given by Australia, that "a '100% 
audit of packing houses' means that each packi ng house will be audited by AQIS officers while they 
are present undertaking fruit inspections for pre-clear ance" is not in line with the explanation given 
regarding the contrast between  a "100% audit of su rvey teams" and "the audit would include 100% of 
survey teams".  It should be clarified, whether this  formulation should be in line with the formulation 
for survey teams, i.e. "the audit would include 100% of packing houses." 
Dr Swinburne (Response to questions 4 and 5)
: 
 43. Australia's IRA (Part A, p.17;  Part B, p. 314- 315) seems to imply that to initiate trade in 
apples with New Zealand AQIS officers would be i nvolved directly in all aspects of the risk 
management systems they wish to see adopted, du ring a period referred to as "Preclearance".  The 
IRA (Part B, p. 313) recognises that MAFNZ would be the competent authority in the registration of 
orchards and issue of phytosanitary certificates, so it is presumably the intention that during this "Preclearance" phase AQIS officers would work alongsi de their MAFNZ counterparts, and be directly  WT/DS367/11 
 Page 13 
 
 
  involved in all inspections.  Australia's responses (R  45-52 by the Parties) suggest that after gaining 
this initial experience the role of AQIS officers would be reduced to that of systems auditors.  What 
are not clear are Australia's requirements for allowi ng the role AQIS officers to evolve from direct, 
hands-on inspectors of all orchards and pack-houses to  that of systems auditors, or how many seasons 
it might take for the transition to be effected. 
II. FIRE BLIGHT 
Question 6 
Please comment on whether an apple fruit may be na turally (i.e., through means other than artificial 
inoculation) epiphytically infested  or endophytically infected with fire blight and still develop into a 
healthy-looking mature fruit.  Please comment al so whether any of the challenged requirements 
imposed by Australia with respect to fire blight a re based on a finding in Australia's IRA that such 
situation is possible.  If so: a. What is the scientific basis contai ned in the IRA for such a finding? 
 
Dr Paulin
: 
 
44. Epiphytically infested fruits:  Fruits may be surface infested and still develop into a healthy-
looking mature fruit, in an orch ard where the disease is active  (that is when symptoms are developing 
on the trees).  Fruits on the trees showing active symptoms may be surface contaminated by ooze 
produced from near-by symptoms, or by direct contact  with diseased parts of the tree (shoots, other 
fruits, late blossoms).  In such an orchard with active symptoms it is possible also that wind-driven 
rain carries bacteria from the surface of sympto ms to fruits, or that rain washes exudate from 
symptoms situated in the upper part of the tree  down onto the fruits.  In this case the bacterial 
population is transient (Thomson, 2000).  Without wounding, the infested  fruit will not be infected , 
and will develop into a normal healthy fruit. If w ounded (hailstorm...) symp toms would develop on 
immature fruits. 
45. Endophytically infested fruits:  I do not know  of any description of internally infected 
symptomless mature fruits.  On an infected tree it can be supposed that few bacterial cells in the 
xylem may migrate up to the fruits, without being ac tive, and therefore without producing symptoms.  
As far as I know, nobody has ever detected su ch endophytic populations in fruits.  Anyhow an 
endophytic detection in mature fru its would suppose that the tree bearing these fruits has had a history 
of fire blight the previous weeks or the previous years. 
46. (a) The scientific basis in IRA for the finding that Erwinia amylovora may be present on and 
in fruits are a number of results obtained in diver se conditions, in New Zealand and the United States, 
showing that  bacteria in small amount may be pr esent in the calyx-end of fruits issued from severely 
infected orchard (Hale et al., 1987).  Results may vary according to detection techniques used (more or less sensitive or specific, some of them unable to separate dead from living cells).  But the general 
picture is that, in an area showing active symptoms of fire blight, a possibility exists that limited 
population of surviving bacterial cells may be prese nt on fruits.  These populations tend to decrease 
with time.  The existence of these surviving populations  (external or internal) is due to the fact that, 
like a number of other bacteria, E. amylovora  has developed a number of tools for its survival in 
"adverse" conditions (starvation,.. etc).  Am ong them, the IRA reports on EPS, quorum sensing, 
VBNC, general regulator of metabolism like sigma fact ors.. etc.  All these allow the bacteria to face 
periods of time where it cannot multiply, a nd therefore to survive for some times. WT/DS367/11 
Page 14  
 
  b. Is the finding in the IRA in this regar d based on respected and qualified scientific sources? 
 
Dr Paulin
: 
 47. Not all the papers included in the IR A with respect  to survival of E. amylovora  associated 
with fruits provide perfectly established results.  As  already mentioned by a stakeholder, some of 
them are very difficult to understand, due to the comp lexity of the design of the paper (van der Zwet 
et al., 1990).  Very often it is not easy to know what is precisely intended by "severe fire blight" in the 
orchard (or in the vicinity), and this makes the resu lts difficult to evaluate, or to extend to the general 
case.  Nevertheless the possibility of the presence of a limited surviving population of bacteria on the 
surface of mature fruits issued from severely inf ected environment, given by the whole data 
presented, seems to be acceptable. 
48. Internal contamination of fruits, on the contra ry is not well established in the IRA:  the 
experiments reporting positive isolation from internal tissue of fruits are not convincing (van der Zwet 
et al., 2000), or obtained in artificial conditions whic h do not represent the conditions of mature fruits 
in the orchard. (Dueck, 1974).  The paper supposed to show that E. amylovora  is associated with 
ovules and seeds is just not credible, due to the l ack of appropriate determination procedure of 
bacteria, and to the presentation of data, which do es not allow the association of a precise bacterial 
species with a corresponding seed or ovule. It remains that E. amylovora  has repeatedly been 
supposed (rather than shown) to be trapped in xy lem vessels (Vanneste and Eden Green, 2000), and, if 
this were really the case, this could result in the presence of E. amylovora  in mature symptomless 
fruits.  To my knowledge, this has never been proven. 
49. Conversely to the above "field" data, the scientif ic data concerning the diverse means for the 
bacteria to survive are well established, in labor atory conditions.  The diverse mechanisms described 
for survival are potential tools for bact eria in general.  They work in E. amylovora  as well.  The 
assessment of the exact role of each of these mechanisms is difficult.  It remains that E. amylovora  is 
not considered as an ubiquist bacteria (like  Listeria  for example) which would have a strong potential 
for surviving and multiplying in diverse ecological niches. 
c. Is the reasoning articulated by the IRA on the basis of such scientific evidence, including the 
methodologies applied, objective and coherent and do the particular conclusions drawn in the IRA 
find sufficient support in the available scientific evidence? 
 Dr Paulin
: 
 50. The reasoning established by the IRA seems cons equently coherent and usually based on 
available evidence, although it may te nd to exaggerate the risks of E. amylovora  associated with fruits 
(mature symptomless). 
d. Do the results of the IRA's assessment in this regard suffic iently warrant the challenged 
requirements relating to fire blight? 
 
Dr Paulin
: 
 51. The results of the assessment therefore suppor t sufficiently the need for information on the 
orchard previous infection, for inspection of orchar ds before export, as well as for the disinfection of 
fruits in the packing houses.  May be the fact that  we are dealing with low populations of surviving 
(not able to multiply) bacteria, and likely to be present only when active symptoms of the disease are 
present in the close vicinity or in the orchard wher e the apples are sourced could be better taken into 
account, with request of less strict prescriptions.  WT/DS367/11 
 Page 15 
 
 
  Dr Deckers (Response to whole question) : 
 
52. In the biological cycle of EA mature apples ar e not included as an important way of spreading 
the fire blight disease.  In contrast to the ab sence of specific measures on export on fruits, specific 
measures are imposed in Europe in the countries wi th fire blight around the fruit tree nurseries with 
the aim to prevent export of contaminated trees from in fected countries to countries free of fire blight.  
The trade of apple fruits between the different count ries is not subjected to special measures.  This 
means that the spread of the fire blight disease by fruit tree nursery material is considered to be much 
more important than the risk for spread by the export of contaminated apple fruits. 
53. Apple fruit can be infected epiphytically and naturally and can still develop into a healthy-
looking mature fruit.  Epiphytical presence of the disease in the calyx end of the fruits has been 
sufficiently documented.  There are circumstanc es that can increase the epiphytical presence of the 
EA bacteria on the apple fruits.  This can happen when there is an important hail damage on the 
immature fruits in an orchard which can result in an  important increase of the bacterial inoculum in 
the orchard with ooze formation on the immature fruits on the hail wounds and the build up of an 
important epiphytical population of Erwinia bacteria on healthy looking mature fruits at the end of the 
season.  Bacterial ooze formation does not occur on mature apple fruits, because the amylum which is 
present in the immature fruits allows a rapid multipli cation of the EA bacteria.  The mature fruits don't 
contain amylum because the amylum is transfe rred into sugars during the maturation process. 
54. The chance to find an endophytically infected fruit that develops to a healthy looking mature 
fruit is not sufficiently scientifically documented in  the fire blight epidemiology.  Whenever an 
endophytically infected fruit would be present on the tree,  there is a great chance that such fruits will 
fall prematurely through internal ethylene formation and will not reach the maturity stage at which the 
fruits are normally harvested. 
Question 7 
Please comment whether the challenged requirements im posed by Australia with  respect to fire blight 
are based on a finding in Australia's IRA that matu re apple fruit can be infected with fire blight and 
that mature apple fruit can disseminate E. amylovora or  serve as a source of new infection/infestation 
in orchards.  If so: a. What is the scientific basis contained in the IRA for such a finding?  
 
Dr Paulin
: 
 
55. The infection  of mature fruits implies that the bacter ia are allowed to enter the mature fruit 
and then that they are able to multiply in  the fruit tissue in order to produce symptoms. 
56. (a) No scientific basis is presented in the IRA which could support this  proposal.  In my 
opinion the papers presented in this respect are based on experiments that are too far from natural 
conditions to be of value in the case of orchard conditions (Azegami et al  2006, Tsukamoto et al  
2005). 
b. Does the scientific evidence support the contention that an apple fruit may be naturally infected 
with fire blight (i.e., infected through means oth er than artificial inoculation) and still develop into a 
healthy-looking mature fruit?  
Dr Paulin
: 
 57. True infection is not reported:  it would need a penetration of the bacteria in the mature fruit, 
followed by multiplication of the bacteria in th e fruit tissues.  This multiplication would produce WT/DS367/11 
Page 16  
 
  symptoms
, therefore the fruit would no longer be symp tomless.  Surface infestation, even if this 
should be rare, could occur, but only in orchards (or areas) where there is an available inoculum 
(ooze), produced nearby by active symptoms of fire blight (see above). 
c. Please comment on the scientific basis for clai ming that mature, symptomless apples could harbour 
endophytic (internal) popula tions of E. amylovora? 
 
Dr Paulin : 
 58. See above for the supposed xylem invasion by bacteria.  In the xylem, the bacteria are 
starving, because the content of the xylem constitut es a very poor medium as far as nutrients for the 
bacteria are concerned.  Then it is expected that  E. amylovora  will not multiply in vessels.  
Nevertheless it could survive for some times, po ssibly at the VBNC stage, before disappearing. 
d. Is the finding in the IRA based on respected and qualified scientific sources? 
 
Dr Paulin
: 
 
59. See (a). 
e. Is the reasoning articulated by the IRA on the basis of such scientific evidence, including the 
methodologies applied, objective and coherent? 
 
Dr Paulin : 
 
60. In my view, there is no basis here for a specific reasoning for prevention of fire blight spread 
in the case of mature apple fruits free of trash. 
f. Do the results of the IRA' s assessment in this regard suffic iently warrant the challenged 
requirements related to fire blight? 
 
Dr Paulin : 
 61. No specific requirements are needed to preven t the risk associated with infected apples. 
Dr Deckers (Response to whole question)
: 
 
62. Mature apple fruits can harbour EA bacteria epiphytically on the fruit skin or in the calyx of 
the fruit.  But it is generally accepted that the fire  blight bacterium is not surviving well as an 
epiphytical bacterium.  On the fruit  skin the EA bacteria will dry out easily and die while in the calyx 
end they will be able to survive for a longer period.   But multiplication of the epiphytical EA bacteria 
in the calyx end of the fruits will not occur;  multiplication of the bacteria will only occur on a 
medium rich in sugar or in amylum.  This means that the level of epiphytic populations of the EA 
bacteria on the apple fruits  will remain low.  This  will make it difficult to detect these low number of 
bacteria on the fruit skin.  The ch ance that this epiphytic population of EA serves as a new source of 
infestation in the orchard is very small is not descr ibed in the biological cyclus of an EA infection 
under orchard condition.  The calyx of the fruit is no t a place where the EA bacteria can multiply ; in 
the best case the bacteria can survive for a period on that place. 
63. There is not sufficient qualified research availa ble that indicate the importance of endophytic 
populations of Erwinia amylovora in apple fruits.  WT/DS367/11 
 Page 17 
 
 
  Question 8 
Based on Australia's IRA, do the challenged requirem ents imposed by Australia with respect to fire 
blight provide for any tolerance of the presence of E. amylovora in or around areas from which 
New Zealand apples would be sourced?  Please comment on whether the following terms express different concepts:  "area freedom", "pest free pl aces of production", "freedom of the disease" and 
"freedom of the visible symptoms of the disease".  How relevant is a distinction between "area 
freedom" and "low pest prevalence" in the context of Australia's measures for fire blight?  In light of 
Australia's IRA and Australia's R 36, how do these various terms relate to relevant ISPMs, in particular ISPMs Nos. 4, 5, 10 and 22?  (Paras . 4.443 and 4.447 of New Zealand's FWS;  paras. 156-
160 of Australia's FWS) 
 
Dr Deckers
: 
 64. Freedom of the visible symptoms of the disease does not mean that the disease is not  present 
on the fruit or that there is a pest free place of producti on.  It only describes the situation of fire blight 
in the orchard and indicates that there is a reduced ri sk for the presence of fire blight bacteria on the 
fruits because there are no active fire blight infections in the considered orchards.  It is important that 
not only the orchards should be fire blight free but also the immediate environment around the orchard should be fire blight free.  The sporadic a ppearance of the fire blight disease in an orchard or 
on another host plant is one of the typical char acteristics of this bacterial disease under orchard 
conditions.  This means that the disease will not be  present every year on the same place and in the 
same intensity. 
Dr Paulin
: 
 65. The IRA indicates that no area can be proved to  be without fire blight in apple production 
zones in New Zealand.  If this is correct, the requi rements are made on the assumption that there is not 
any orchard from which apples are exported which is (or has ever been in the 50 last years) without 
fire blight:  therefore the IRA provi des a certain level of tolerance. 
66. – "Area freedom":  Area without fire bight, the disease is regularly surveyed and has never 
been seen , or reported (for example:  South Africa) ISPM 4. 
67. – "Pest-free places of production":  Places without fire blight (likely orchards or nurseries) 
within an area where the pest (fire bight) is presen t, (for example, it would be the case of Corsica, 
which is surveyed without fire blight, in France where fire blight is present) ISPM10. 
68. – "Freedom of disease":  No symptom ever seen.  The trees are supposed to have never been 
infected by E. amylovora.  Therefore should be used only in "area freedom" or "pest free place of 
production". 
69. – "Freedom of the visible symptoms of the disease":  No symptom seen (during this growing 
season), or symptoms immediately removed. 
70. – "Area freedom":  Should be an area without symptoms. 
71. – "Low pest prevalence" ISPM 22:  A zone where the disease is poorly active and therefore 
the symptoms are rare (low number of diseased plants, and limited development of symptoms).  This is basically different from ISPM 4, which is ar ea freedom.  In a low pest prevalence area some 
symptoms are likely to be present, at least from time to time. WT/DS367/11 
Page 18  
 
  Question 9 
What is the scientific basis in Australia's IRA for the requirement relating to the suspension of exports 
on the basis of evidence of pruning?  Is the reasoning  in the IRA with regard to the use of pruning as 
a possible means to remove or hide symptoms of fire blight objective and coherent?  Is such reasoning 
based on respected and qualified scientific sources?   Do the results of  the IRA's assessment 
sufficiently warrant the challenged requirement relati ng to the suspension of exports on the basis of 
evidence of pruning as a possible means to remove or hide symptoms of fire blight? 
 
Dr Deckers
: 
 
72. Pruning out the fire blight infections during grow ing season is a control measure that is taken 
in many countries to keep the fire blight situa tion under control in an orchard.  It should not be 
regarded as a way to hide the fire blight infec tions because this pruning out of the fire blight 
infections during season can easily be distinguished from the standard pruning measures that are made 
during dormant season.  It seems to be logic that Au stralia takes into account this fire blight control 
measure when making the evaluation of the fire bli ght situation in an orchard.  Suspension of the 
export when recent fire blight pruning in an orchard has been observed seems to be a logic measure in 
the IRA. 
Dr Paulin : 
 73. The scientific basis of this requirement is that symptoms of fire blight develop in spring and 
early summer, associated with the presence of blosso ms and then actively growing shoots.  The main 
infection period is the blossom period.  If an orch ard is infected in spring or early summer, the 
development of symptoms will stop in summer and autumn.  If the trees are trimmed for suppression of symptoms, it could well be that the orchard l ooks symptomless when actually it has shown activity 
of the disease (and hence production of ooze with ba cteria), which could have consequences on fruit 
infestation.  In addition, it remains possible that a renewal of activity of the disease takes place after 
the inspection, but before cropping.  That would be a situation resulting in a risk (even if weak, see 
question 6) of surface infested fruits. 
74. The reasoning of IRA is therefore coherent and objective (as soon as it limits the ban of 
pruning, for export orchards to the pruning whic h takes place after the beginning of the blossom 
period) . 
75. This assessment of the suspension of export is soundly based on the evidence of this late  
pruning (obviously winter-pruning is a standard procedure in tree management). 
Question 10 
Part of the analysis of exposure and establishment w ith respect to fire blight in Australia's IRA 
proceeds on the basis that host plants in Australia are susceptible to being na turally infected with 
E. amylovora (i.e., infected through means other than artificial inoculation).  (IRA, Part C, p. 105;  
R 66 by the Parties) a. What is the scientific basis contained in the I RA for such a finding, including the scientific basis for 
assuming that such hosts would be susceptible to be ing naturally infected during the same periods in 
which apples from New Zealand would be imported by Australia?  
 Dr Paulin
: 
 76. As a preliminary comment it could be indicated that the 150 species of host plant described in 
the literature do not represent
 the number of species actually exposed to the disease in natural 
condition (as underlined in the IRA).  It seems more  realistic to consider only the 10 "true" host 
species that are cited in the IRA as hosts of  primary and secondary economic and ecological  WT/DS367/11 
 Page 19 
 
 
  importance.  Very likely, the other ones would play no role in the installation and spread of the 
disease.  In addition, in each of these host species, not all the cultivars are susceptible to fire blight.  
That means that among these 134 groups of plants theo retically exposed to develop the disease, only a 
restricted proportion is actually at risk:  some cultivars only among 10 of these 134.  But these cultivars are economically important, of course, and they can be expected to be as susceptible in 
Australia as they are in other parts of the world. 
77. (a) Host plants of fire blight, when susceptible , do not show a consta nt receptivity to the 
disease along the growing season.  This receptivity to na tural infection may be totally absent:  this is 
the case in dormant period (winter) and when the shoots  are not growing, that is generally (it depends 
on the host species) in late spring and summer.  Conve rsely, the receptivity to infection is high during 
blossom period, and during shoot growth.  Classica lly, for most host plants of fire blight, shoot 
growth takes place after blossoming, and stops in early summer.  Obviously this timing will depends 
on local conditions (water supply, nutrition of the pl ant, temperature, pruning...).  In addition, shoot 
growth in some cases (hawthorn) takes place before  bloom (early spring).  For most host plants 
natural infection is easier during bloom. Shoot infecti ons are often related to summer hailstorms.  This 
applies to each host of fire blight.  For each hos t the blossom period and the shoot growth period are 
specific in their date of appearance and in their dura tion.  Theoretically, it is possible that at least 
some of the host plants are in bloom or shoot growth nearly all the year round:  for example Chaenomeles  blooms in winter, Cotoneaster  in early summer.  To be more realistic, I think that the 
risk is high, in case of introduction, only in sp ring and early summer, with a possible additional 
dangerous period in summer and late summer if so me hosts such as certain cultivars of apple and 
mainly of pears produce secondary blossoms (blo ssoms opening after the normal blossom period, 
usually associated with some physiological disorder).  In addition, the probabili ty of infection will be 
associated with the number of hosts at the suitabl e stage at the moment of introduction.  In this 
respect, the maximum period of su sceptibility to an introduction of E. amylovora  will be the full 
bloom period of pears, and then of apples. 
b. Is the finding in the IRA in this regar d based on respected and qualified scientific sources? 
 
Dr Paulin
: 
 78. Against this background it is difficult to tell when an introduction of E. amylovora  would be 
most prone to turn into a natural infection.  But it can be assumed that most of the time during the 
year most host plants should not  be at a receptive stage when the import of apple would take place 
(peak in winter). 
c. Is the reasoning articulated by the IRA on the basis of such scientific evidence, including the 
methodologies applied, objective and coherent, and do the particular conclusions drawn in the IRA 
find sufficient support in the available scientific evidence? 
 
Dr Paulin
: 
 79. The reasoning of IRA is coherent, but maximi ses the real risks in considering too high 
number of host plants, and in taking no account of  the discontinuity in susceptible host plants 
receptivity during the year. 
d. Do the results of the IRA's assessment in this regard sufficien tly warrant the challenged SPS 
measures related to fire blight? 
 WT/DS367/11 
Page 20  
 
  Dr Deckers (Response to whole question)
: 
 80. For the realisation of a fire blight infecti on there must be a co-incidence of 3 important 
factors: 
81. (1) The host plant must be in a susceptible st age of development e.g. flowering time is a 
susceptible stage. 
82. (2) The climatological conditions for an EA inf ection should be sufficient with appropriate 
temperatures and relative humidity for bacteria l multiplication followed by an infection. 
83. (3) The EA bacteria must multiply on a susceptible  organ (e.g. stigma on the style of a flower) 
before the infection can take place.  Rain is often an  important factor to transmit the bacteria from the 
multiplication site to the infection site.  This m eans that drought can limit the spread of the EA 
bacteria. 
84. For each factor an evaluation can be made for the infection conditions under Australian 
conditions at the moment of apple fruit import.  During dormant season, there is no infection 
possibility of the fire blight host plants when the hos t plants don't have the susceptible organs or when 
the climatological conditions are not allowing bacterial multiplication. 
Question 11 
Based on the relevant parts of Australia's IRA, do you consider the IRA to be objective and credible 
when qualifying the biological and economic conse quences of fire blight as "high"?  Can you 
comment on the specific meaning given in the IRA for the impact score for "high" and, in particular, 
how it compares with what is considered to be a "h igh" impact with respect to other risks?  (IRA, 
Part B, p. 104;  paras. 493-523 of Australia's FW S;  paras. 4.253-4.264 of New Zealand 's FWS;  
R 67-68 by New Zealand) 
 
Dr Deckers
: 
 
85. The biological and economical consequences of a fire blight introduction can indeed be 
classified as "high". 
86. The biological and economical consequences of a possible fire blight infection in Australia 
depends of the success of the installation and the spr ead of a new infection on a possible host plant.  
The different regions in Australia will not have all the appropriate  climatological conditions for an 
optimal EA infection and development.  Further,  there will be differences in disease development 
from one year to another: this is typical for an in fection of EA that the disease incidence is not the 
same every year. 
Dr Paulin : 
 (a) Direct impact 
87. Economical consequences of introduc tion of fire bight in Australia:   I am not sure that fire 
blight is the most serious disease of apple everywhe re.  Apple scab would be probably considered as 
more costly in many areas.  But fire bli ght is undoubtedly the most serious bacterial
 disease of apple 
and pear.  It is impossible to predict the economical consequences of the introduction of fire blight in 
a new area.  The severity of the disease (the importa nce of damages) is the result of the combination 
of three factors (at least) at the local level:  climate, cultivar susceptib ility (genetic), cultivar 
receptivity.  If each can be evaluated (at least for trends) the combination of the three to give a 
reasonable prediction is non realistic .  Nevertheless it explains that it is just not possible, and it has  WT/DS367/11 
 Page 21 
 
 
  never been seen, that fire blight is devastating to the same degree at any place and on any plant as 
soon as introduced in a new area.  In addition the sp read of the disease, even if not eradicated, is 
relatively slow, and the invasion, if any, should be  progressive.  The damage to crops is difficult to 
estimate.  In France, as far as I can tell, I have not  seen a large number of bearing trees of apple killed 
by fire blight, in spite of the high susceptibility of so me of our varieties.  This is not true for pear 
varieties, but the disappearance of entire trees due to fi re blight remains limited to few varieties only.  
The overall production of fruits in a whole country has never been seriously decreased, even by a 
severe fire blight epidemy, even if damages can be ve ry costly at the local level, in certain years for 
certain varieties.  Therefore the impact score of "F" could be exaggerated. 
88. Biological consequences of introduc tion of fire bight in Australia:   Up to now, in the different 
areas invaded by fire blight in the world, the introduction of the disease has had limited biological 
(ecological) consequences (at worse serious limitati on in certain zones of specific cultivars of fruit 
trees (pears) and ornamentals).  To my knowledge it has not induced the disappearance of any grown 
or spontaneous species of plant.  I do not see for wh ich reason it would be very different in Australia. 
89. In this case, the score of "A" seems correct. 
(b) Indirect impact 
90. Conversely, the introduction of fire bight in Australia would be a very serious issue.  
Actually, even if the destruction of plants by the disease itself was limited, the simple introduction  of 
the disease in a "new" country is costly, due to the fact that E. amylovora  is a quarantine disease for 
many countries, and that the status of "without fire blight", for a country, implies a number of commercial advantages for export of plant material ( to say nothing of the fruits? ).  The attempts at 
eradication would be very costly.  Comparatively, th e cost of additional sprays requested by the risk 
or presence of fire blight seems almost negligible.  But the lost of the "without" status with respect to 
quarantine could justify a "F". 
91. Domestic trade:   Given the likely low impact at the national level of the disease on overall 
production, the losses for domestic trade or industry look exaggerated and unrealistic. 
92. International trade:   The impact could be strong on nursery exports due to quarantine 
restrictions, but this is not suggested in the IRA.  The impact on fruit trade will be limited, especially 
if the eradication methods are effective (it will not  be possible to consider any apple orchard of 
Australia as infected by fire blight).  Again the rating of "D" seems too high. 
93. Communities:   This is related to the loss of productio n.  As seen earlier it is not likely that the 
loss is perceptible at the national level.  An impact , if any, on job availability would concern only a 
very local level, not national. 
94. The qualification of "high" for the impact of fire  blight is to my eyes appropriate, based on the 
possible international consequences of this introduction.  Although it can be argued that E. amylovora  
has already been found in Australia. 
95. I have no idea on other threats to a pple and pear production in Australia. 
Dr Schrader
: 
 96. The Australian IRA Guidelines do not give ex amples for ratings.  This is a general 
shortcoming in many risk assessment guidelines.  However, for example, the Canadian Risk 
Assessment Scheme includes guidelines for rating.  There, an economic impact is rated as "high" 
when "the pest has a severe impact on the standing crop with significant host mortality" (Plant Health WT/DS367/11 
Page 22  
 
  Risk Assessment, Commodity Risk Assessment, Cana dian Food Inspection Authority, Plant Health 
Risk Assessment Unit, Science Advice Division). 
97. In the case of fire blight, the rating of high for economic consequences would be adequate, as 
this bacterium can cause severe damage to the crop as well as to the plants themselves.  After 
favourable weather conditions during bl ooming, yield is considerably reduced and in it is possible that 
there is no or nearly no yield at all.  In the follo wing year, productivity is also significantly affected 
due to the destruction of fruiting spurs.  In suscep tible hosts the infection spreads so quickly through 
the plant that, once infected, trees cannot be saved, ev en by drastic and immediate surgery, and die in 
a short time after the first visual signs of infection.  (e.g. Van der Zwet, T., Keil, H.L., 1979:  Fireblight:  a bacterial disease of rosaceous  plants.  USDA Agriculture Handbook No. 510). 
Dr Sgrillo
: 
 98. IRA is objective in qualifying the economic c onsequences.  However IRA makes very few 
references to actual losses caused by E.amylovora  elsewhere. 
99. Although fire blight is distributed in more than 50 countries
2, IRA cites only three cases of 
losses (direct impact in plant health) by E.amylovora :  New Zealand in 1998, USA in 1976/77 and 
USA/Michigan in 2000.3 
100. The economic losses of New Zealand in1998 we re estimated in 2.8% of the country 
production.4 
101. The losses of USA in 1976/1977 were estimated in US$ 2-5,000,0005.  The values of apples 
production in 1976/1977 were US$ 566,102,000 and 620,979,0006 respectively.  Therefore, the losses 
caused by fire blight correspond to 0.35% and 0.80% of the country production respectively. 
102. The outbreak that has occurred in Michigan, US A in 2000 is analyzed by Longstroth (2001).7  
This author describes losses of 15% of the trees,  9% of the area and 37.5% of the production in 
southwest Michigan, which contains 29% of the appl es acreage of the State of Michigan.  The losses 
for the Michigan state were then 4.4% of the tr ees, 2.6% of the area and 10.8% of the production. 
103. Fire blight is a serious disease of pome fruit trees.  However, based in the figures above, the 
consequences considered by IRA8 (country loss of 50% and 20% for pear and apple respectively) 
seem to be overestimated.  Should be considered al so that the perfect fire blight conditions, unusually 
warm, humid and wet weather, are expect ed to occur only once in each 10 years.9  To clarify these 
points would be necessary additional information on losses in countries where the E. amylovora  
occurs. 
                                                      
2 (footnote original ) Exhibit NZ-6 European and Mediterranean Plant Protection Organization (EPPO), 
(1997) Data Sheet on Quarantine Pests: Erwini a amylovora, prepared fo r the European Union. 
3 (footnote original ) IRA pp. 98-99. 
4 (footnote original ) New Zealand 's FWS para. 4.261. 
5 (footnote original ) IRA p. 98. 
6 (footnote original ) Reference 09:  Crop Values 1975 1976 1 977 – Season Average Prices Received by 
Farmers and Value of Production.  USDA Economic, Statistic, and Market Information System. 
7 (footnote original ) Exhibit AUS-44: Longstroth M. (2001) "The 2000 fire blight epidemic in 
southwest Michigan apple orchards", The Compact Fruit Tree 34 (1), pp. 16-19, p. 16. 
8 (footnote original ) IRA p. 99. 
9 (footnote original ) New Zealand 's FWS paras. 4.256, 4.260.  WT/DS367/11 
 Page 23 
 
 
  104. The IRA categories10 to assess potential impact in the production may be summarized as: 
"Unlikely to be discernible":  No production losses 
"Minor significance:  Minor production losses;  reversible effects "Significant":  Moderate production losses;  effects reversible or not "Highly significant":  Large production losses;  irreversibly effects 
 
105. The impact score for moderate production losses in national level (significant) or large 
production losses in regional, district or local level (highly significant) corresponds to category F, 
according to IRA's Table 10.
11  The overall consequences are considered to be high  if the 
consequences of the pest with respect to a single criterion are F. 
106. The high impact score is compatible with the lo sses caused by fire blight described in the 
literature, as reported in EPPO data sheet: 
"The fire blight pathogen causes considerable  damage to susceptible hosts.  It is not 
only destructive to the current year's crop but also extremely dangerous to the plants 
themselves.  After favorable weather conditions during blooming, yield is 
considerably reduced and in some cases nullified.  The next year's productivity is also 
significantly affected because of  the destruction of fruiting spurs.  In susceptible hosts 
the infection spreads so rapidly through the tree that, once infected, trees cannot be 
saved, even by drastic and immediate surgery,  and die in a short time after the first 
visual sign of infection.  In some states of  the USA, pear cultivation has been largely 
abandoned because of the disease."12 
Question 12 
What is your understanding as to how the likelihood of entry, establishment and spread into Australia 
of Japanese Erwinia associated with Japanese nashi pears could be co mpared to that of 
Erwinia amylovora associated with New Zeal and apples?  Is there a sound scientific basis for 
New Zealand's argument that there are comparabl e risk profiles at issue in the case of 
Japanese Erwinia and Erwinia amyl ovora, considering also the potential biological and economic 
consequences?  (Paras. 4.436-4.439 of New Zealand' s FWS;  paras. 986-987 of Australia's FWS;  and 
R 101 by Australia) 
 
Dr Deckers : 
 
107. There is a great similarity between the Japanes Erwinia associated with nashi pears and 
Erwinia  amylovora  on apples from New Zealand.  In both cases it concerns a bacterial disease on 
fruits, the one Japanese Erwinia  on pear and the other fire blight one on apple and pear.  This 
distinction will of course have consequences for the gl obal risk evaluation.  On the other hand the risk 
for epiphytical presence of the bacteria on the surface of the fruits is comparable for both bacteria and 
should ask for a comparable strategy to avoid entrance of the disease. 
Dr Paulin : 
 108. The key-difference between the two situations , as far as risk associated with fruits is 
concerned, is that, according to Australia (fo llowing Japan statement), this disease caused by 
Erwinia sp.  on Nashis is present only
 in the Hokkaido Island.  This allows Australia to import fruits 
                                                      
10 (footnote original ) IRA p. 38. 
11 (footnote original ) IRA p. 39. 
12 (footnote original ) Exhibit NZ-6 European and Mediterranean Plant Protection Organization (EPPO), 
(1997) Data Sheet on Quarantine Pests:  Erwi nia amylovora, prepared fo r the European Union. WT/DS367/11 
Page 24  
 
  from an other area, remote from Hokkaido.  This is a clear objective difference between 
Erwinia /Japan, and E. amylovora /New Zealand situations. 
109. Otherwise it seems that the bacteria ( Erwinia -Japan and E. amylovora ) are very similar but 
not identical
, and the symptoms seem similar as well, but Erwinia from Nashis shows a narrow range 
of host plants, which could account for lower risks (lim ited to pears?).  To be honest it is important to 
recognise that little is known in the literature about this Nashi disease. 
110. In addition it is not certain that this particular Erwinia  from Japan be considered as a 
quarantine pathogen.  Therefore the limitations in in ternational trade could not be a consequence of an 
introduction.  Again, too little knowledge is  available on this Nashi disease to be sure. 
Question 13 
What is your understanding as to how the relevant measures identified in Australia's IRA compare to 
the domestic measures imposed by Australia in reac tion to the fire blight incursion at the Melbourne 
Royal Botanic Gardens in 1997?  What facto rs would be relevant in assessing whether any 
differences or similarities between the two sets of measures applied in these two situations could be 
used to determine the coherence of the reasoning c ontained in Australia's IRA?  (Para. 4.262 of 
New Zealand FWS;  paras. 77, 356 514 of Aust ralia's FWS;  and R 69 by the Parties) 
 
Dr Deckers : 
 111. The domestic measures imposed by the Australia n government in reaction to the Melbourne 
outbreak included  also a restriction in apple and pear movement in the whole state of Victoria.  This 
is compatible with the risk estimation in the IRA of the apples imported from New Zealand.  There 
was also a restriction on the movement  of the fire blight host plants in the Melbourne area and all the 
host plants in the botanical garden were removed.  Th is is in contrast with the measures that should be 
taken in the orchards in New Zealand:  also in the orchards the infections should be removed and 
burned as soon as possible to avoid a wide  spread of the fire blight disease. 
Dr Paulin
: 
 112. The relevant measures in IRA should compare in the eradication, destruction of diseased and 
healthy plants in the surroundings, surveys and di agnostics, which were undertaken:  such measures 
should be taken in case of an introduction with fruits .  The survey was probably far more difficult to 
organize in the case of the Bo tanical Garden, due to the absence of credible hypothesis
 on the origin 
of inoculum (site and date).  If an introductio n associated with fruit import was experienced, the 
survey would be far simpler, because the exact pl ace and date of the intr oduction would be probably 
soon traced out.  In addition, it should be underlined  that in no country, even in recently infected 
countries with only scattered sites of infection (such as Spain, for example), the restriction of trade of 
mature fruits inside the country has never been sugg ested or implemented to limit the risks of spread 
of further of the disease. 
113. The diverse levels of action should be the same in the two cases.  Nevertheless, as far as I 
know, the Botanical Garden case was discovered on a re latively isolated plant (paucity of potential 
host plants in the immediate surroundings).  The domestic measures could be more difficult (more 
plants to be destroyed in the surroundings of the firs t blighted tree) if the symptom was detected first 
in an orchard, surrounded by hundred of trees of  the same variety, and therefore the same 
susceptibility at the same stage of receptivity. 
Question 14 
Please comment on the alternative measures proposed  by New Zealand in respect of fire blight, 
namely (i) restricting apple fruit imports to fruit that  has been cold stored, or (ii) limiting imports to  WT/DS367/11 
 Page 25 
 
 
  apples that are "retail-ready packaged fruit".  How do these measures compare to the relevant 
measures imposed by Australia in terms of risk m itigation?  (IRA, Part B, pp. 4-5 and 105-115;  
para. 4.490 of New Zealand's FWS;  and para. 1087 of Australia's FWS) 
 
Dr Deckers : 
 
114. A cold storage period can reduce the epiphytical  EA populations on the fruit surfaces but will 
not be able to eliminate these populations completely.  Limiting the imports to the apples that are retail ready is not excluding apples that could host so me fire blight bacteria in their calyx end of the 
fruits.  This means that both measures proposed by New Zealand will not reduce the risk sufficiently. 
Dr Paulin
: 
 115. (a) Import of fruits which have been cold-stored.   Results from (Hale and Taylor, 1999, and 
others) show that the bacterial population harboured on  fruits decreases over time during cold storage.  
Nevertheless it cannot be expected that this proce dure will for sure allow to obtain to disappearance of 
all living cells
.  Cold temperature is known to prevent bacterial multiplication ( E. amylovora  will not 
multiply under 3-5°C (Paulin, 2000)).  But on the ot her hand, low temperature (4°C) is the condition 
under which bacteria are kept alive in the laboratori es for longer periods than at room temperature.  
Therefore it is not possible to rely on cold storag e condition to ascertain that not a single bacterial cell 
will remain alive.  It is reasonable though to assume that along with time, bacterial populations 
(unable to multiply) will decrease.  Among the op tions evaluated by Australia (source apple from 
orchard without symptoms, chlorine disinfection)  cold storage is probably the less effective. 
116. (b) Retail-ready packaged fruits.   In my understanding of this qualification of these fruits, the 
apple exported will be symptomless mature apple, in boxes.  This means that an additional check  of 
fruit aspect is performed when appl es are placed in boxes, and adds a safety degree with respect of 
both "symptomless" and "mature".  But the main inter est of this additional step (placing the fruits in 
boxes) is that it will eliminate absolutely the risk of carrying trashes  (from orchards) in association 
with fruits.  In my view trashes may be twigs, dr ied pieces of leaves, plant debris, which could have 
been infected by E. amylovora  before being transformed into tras hes, and which could be equivalent 
of "cankers", which are the natural form of con servation of the disease in the field (Thomson, 2000).  
Such trashes could serve as vectors b ecause if they result from infection , they may harbour internal 
population of bacteria.  But they are visible and completely eliminated in the normal process of 
packaging of the fruits.  The mitigation of risk through this way of packaging would be drastic . 
Question 15 
Please comment on whether the alternative measure proposed by New Zealand in respect of fire 
blight to create a mandatory requirement that app le exports to Australia be limited to "mature, 
symptomless apples" would achieve Australia's ALOP.  How does this measure compare to 
Australia's measures in terms of risk mitigation?  (IRA, Part B, pp. 4-5;  paras. 4.492-4.512 of 
New Zealand's FWS; and paras. 1082-1086 of Australia's FWS) 
 
Dr Deckers : 
 117. The limitation of apple exports to mature sy mptomless apples is not enough to achieve 
Australia's ALOP.  Traceability of the fruits to the level of orchard where the apples have been 
produced is necessary for the risk evaluation in Aust ralia.  Fruits from heavy infected orchards or 
from orchards with hail damage can harbour the bacteria in the calyx end of the fruits. 
Dr Paulin
: 
 
118. "Mature symptomless apples" WT/DS367/11 
Page 26  
 
  119. Mature :  Indicates that fruits have completed their development on trees, and therefore that 
they were not infected at an early stage (otherwi se they would not achieve this development up to the 
mature stage).  Mature fruits are recognized as resistan t to infection:  they do not develop symptoms if 
inoculated , because they do not allow th e multiplication of bacteria. 
120. Symptomless  means that they show no fire blight (or other disease) symptoms:  this eliminates 
infected fruits issued from early infections. 
121. Both these measures are actually necessar y to eliminate the more evident
 risks of transfer of 
the bacteria with fruit.  It decr eases the risk drastically in elimin ating the opportunities of carrying 
high population of E. amylovora  which are associated with tissues harbouring progressive infection, 
for example in immature fruits.  Nevertheless it ca nnot be considered as eliminating absolutely the 
risk of introduction of low (external) bacterial popul ations associated with fruits.  It can then be 
considered to decrease the likelihood for entry of th e bacteria with fruits from very low to extremely 
low, in the ALOP. 
122. The restriction of export to mature symptomless  apples would make even safer the different 
measures taken by Australia (disinfection, st orage...), but could not replace any of them. 
Question 16 
Please comment on whether there is a sound scien tific basis for claiming that recent fire blight 
incursions in territories different from those of Aust ralia and New Zealand can be attributed solely to 
the introduction of nursery stock from infected areas?  Is there any indication that trade in apple fruit 
had any role in these incursions?  (Para. 3.53 of New Zealand's FWS;  para. 80 of Australia's FWS;  
R 61 by New Zealand) 
 
Dr Deckers : 
 123. Between the different countries in the European union, the risk for fire blight introduction in 
new countries by infected plant material ( variety an d or rootstock) is estimated much more important 
than the introduction possibility by infected apple fru its.  In Spain there is a strong indication that 
some of the fire blight infections was related to the import of infected host plants coming from 
Belgium.  Therefore there is a European legisla tion regulating the control measures in and around the 
fruit tree nurseries.  The risk for introduction of the disease by infected fruits is estimated much lower 
and no special measures for the export of fruits are undertaken between the different countries in 
Europe. 
Dr Paulin
: 
 124. Let us consider some "recent" introductions in new countries (introductions which took place 
from 1962 up to now), these where mainly Egypt 1962,  then UK 1966, then continental Europe:  
Poland, The Netherlands, France and Belgium 1972. 
125. First of all it is necessary to keep in mind that the first assessment
 of the disease in any new 
place is NOT the first discovery , and this is worse for the first published  assessment.  Nevertheless 
our knowledge relies usually on the first official (pub lished) assessment.  That means that in most of 
the cases we lack the exact information that we woul d need to discuss accurate ly on the actual cause 
of introduction in each case.  The information that we get is usually the situation when the disease is 
obvious  to local people (who in most cases have not sp ecific training to detect this disease, which is 
new to them).  This is to say that places, plants, and dates which are given in the relevant literature as 
the actual data of the first introductio n in a new zone are probably never  the real data.  WT/DS367/11 
 Page 27 
 
 
  126. In this context it just impossible to ascertain or to deny on the sole basis of the characteristics 
of the first assessment of fire blight in a new site the real  origin of this introduction.  At best some 
evidences can be assessed: 
127. – Most first assessments in Europe where not in or near-by nurseries  (UK, France, The 
Netherlands, Denmark...).  Although it is likely that in any given place where orchards are planted at 
least some nurseries can be found, it seems that at least the zones of first assessment (Egypt, UK, 
France, Belgium…) do not coincide with zones of active nurseries. 
128. – In the cases on which I can personally testify (Samson and Paulin 1972), first discoveries in 
France where in an area with no pear and apple or chards, and no nursery.  The first symptoms were 
found on Crateagu s constituting hedges around meadows for cattle breeding.  The same situation was 
for Denmark and western coast of Germany (Schlesvig-H olstein) some years before.  In these cases at 
least, the introduction through nursery stock seems very  unlikely, and birds, or wind-driven rain (or 
insects) carrying bacteria from actively oozing orchar ds in South East UK were proposed as vectors- 
but this was impossible to prove. 
129. – The first introduction, in any part of the world,  has never been associat ed (Van de Zwet and 
Bonn, 2000) with the vicinity of fruit storage or import premises.  Many examples may be found of 
introductions that are not fully explained, but I have never heard in these introductions of the 
hypothesis or even the likelihood of an introduction with import of fruits. 
130. – In my personal experience with fire blight th at I have had the opportunity to visit soon after 
its supposed first introduction (UK, Denmark, France , Belgium, Israël, Lebanon, Syria…), the most 
common suggested cause of introduction was "wind driven bacteria" rather than nursery stocks. 
131. – It remains that the introduction with nursery stock is not only conceivable, but also easy to 
demonstrate experimentally.  It has been described convincingly in several cases.  But it is evident 
that it is not the sole mode of dispersion of the disease, and probably not even the most frequent . 
Question 17 
Paragraphs 357-359 of Australia's FWS refer to a paper by Billing and Berrie (Exhibit AUS-26), 
which appears to conclude that plant materials or  fruit bins contaminated with E. amylovora may 
have been responsible for the introduction of fire b light into the United Kingdom.  Are you aware of 
any scientific evidence confirming or experimentally t esting this hypothesis?  Does this paper provide 
reliable scientific evidence that the spread of fire b light may be related to the movement of mature 
apple fruit?  How does any such evidence relate to  the relevant evidence relied upon by Australia's 
IRA? 
 
Dr Deckers : 
 132. The paper of Billing and Berrie formulates a hy pothesis of possible fire blight introduction 
into the Kent area in UK but does not prove the way of introduction by mature fruit sufficiently 
scientifically.  I had the opportunity to discuss th is matter with Eve Billing in a personal discussion 
and she considers more the bacterial ooze as a factor  of spread of the disease in the contaminated fruit 
boxes.  Bacterial ooze can be present on fruits  coming from heavily infected orchards. 
Dr Paulin
: 
 133. The paper from Billing and Berrie wh ich is referred to by Australia is a scientific paper which 
is devoted to looking at any epidemiologically plausible explanation for the introduction of fire blight 
in south east UK which would be coherent with the activity of the disease as related to climate.  It is by no means a work that intends to provide "scientif ic evidence".  At best it gives indications on what WT/DS367/11 
Page 28  
 
  is "not impossible"
.  In this context, it is normal that the discovery of crates originating from New 
Zealand found at that time in newly contaminated orchard is cited.  As far as I know, the actual 
presence of bacteria on these bins has not been checked , and neither has been the transportation of this 
putative inoculum to receptive host plants.  Ther efore this fact does not add any element to the 
dispute.  In addition this paper suggests "rotten p ears", as possible vehicles for the bacteria, but never 
"symptomless apples".  This could mean that these authors were not in the opinion that apple - or 
healthy looking fruits- could play a role in this spread ?  Keck et al (1995) demonstrated that on crates 
(wooden and plastic) artificially polluted with suspensions of bacteria, E. amylovora  may survive up 
to 4 months at 4°C.  That can be considered as a po ssible first step for this way of dissemination.  But 
much would remain to be found to confirm that the complete succession of steps is likely to occur to 
reach the infection of a new host plant.  May be it is relevant to indicate that the paper from Berrie 
and Billing ends with the following quotation:  "S cientific knowledge is a body of statements of 
varying degrees of certainty, some most unsure, some  nearly sure, none absolutely certain".  It seems 
to me that this shows that the authors themselve s were well aware that they were not providing any 
"scientific evidence". 
134. This cannot be considered to support the evidence relied upon by Australia. 
Question 18 
Please comment on whether there is a sound scientific  basis for claiming that mature, symptomless 
apples could harbour epiphytic (external) populations of E. amylovora and that a transfer mechanism 
exists that would be capable of transmitting E. am ylovora from such apples to a susceptible host such 
that a fire blight infection would be initiated und er natural (as opposed to laboratory) conditions?  
(Paras. 4.13 and 4.15 of New Zealand's FWS;  par as. 250-262 of Australia's FWS;  R 61 and 62 by 
New Zealand) 
 
Dr Deckers : 
 
135. Mature symptomless apple fruits coming from h eavily infected orchards can harbour an 
epiphytic population of EA bacteria in their calyx end or as bacterial ooze sticked on the fruit skin and 
dried out, but the chance that this bacterial populatio n will be capable to start a new infection on a 
susceptible host plant under natural conditions is rather low. 
136. When the fruits are harvested from orchard without  active fire blight symptoms in and around 
the orchard, without the presence of hail and when the fruits have been disinfected during preparation 
in the packing house, the chan ce for an initiation and establishment of the disease under natural 
conditions in another area is cons idered to be extremely low. 
Dr Paulin : 
 137. As explained earlier (question 6), mature symptomless apple may harbour some surface cells 
of E. amylovora,  at least if collected in an orchard showing active symptoms before cropping time.  
The only "mechanisms" I can think of for the transfer of such bacteria to infection site on a living 
susceptible host plant at the proper stage of receptivity are: 
− Insects (whatever they are, pollinating or not), which could take bacterial cells to 
open blossoms, or to wounds on growing shoots, 
− Wind driven rain. 
138. These two "mechanisms" suppose a close proximi ty between these fruits and the infection 
sites.  Both are questionable
, due to the expected low or very low level of the bacterial population 
present on these fruits, and its localisation (calyx),  which makes the accessibility of cells rather  WT/DS367/11 
 Page 29 
 
 
  difficult.  In addition, bacterial cells on fruit are probably not embedded in ooze (as they are when 
actively multiplying from active lesions) and theref ore not well protected from adverse conditions, 
and, which is more, probably have not the adhesive  capacity, which is said to be a facilitating factor 
for transportation by insects . 
Question 19 
Please comment on whether there is sound scientific  evidence that epiphytic infestations by 
E. amylovora exist on mature apple fruit in quan tities that are under natural conditions capable of 
reproduction;  being transferred to a host plant;  a nd ultimately initiating an infection in that host 
plant?  (Paras. 4.14-4.30 of New Zealand's FWS;  paras.  250-262 of Australia's FWS) 
 Dr Deckers
: 
 139. There will be no multiplication of the epiphyti c bacterial population on the fruit surface or in 
the calyx tissue.  The fire blight bacteria are not  surviving well as an epiphytic bacterial population.  
The bacteria should be transferred first to a susceptib le organ of a fire blight host plant like a stigma 
of a flower where the bacteria can multiply and start a new infection.  The chance for such a 
successful transfer and multiplication of bacteria will be rather exceptional. 
Dr Paulin
: 
 140. We have already commented on the probability of the presence of residual population of 
bacteria on fruit surface.  Some people prefer to use the word "epiph ytic" exclusively for 
microorganisms that are able to multiply
, and therefore to reach high level of population on leaves or 
plant surfaces, without producing symptoms.  This is typically the case of some phytopathogenic bacteria called Pseudomonas syringae  (some pathovars of this species).  Such a capacity does not 
exist  in the case of E. amylovora  (Thomson 2000), except on stigma in flowers.  Therefore the 
bacterial cells eventually present on the fruit surface could not multiply on the same site.  They should 
be first carried to a suitable site for multiplication  (i.e. an infection site, presumably an open flower on 
a host plant). 
141. The transfer to an host plant could be perform ed most likely by insects or wind driven rain, 
but the probability of successful localization at the right place should be very low, and the probability of infection even lower.  The highest probability I can think of is a pollinating insect taking the few 
bacterial cells to the hypantium of a flower of an host plant.  This remains unlikely because trace 
bacterial populations (not multiplying) will be hardly grasped by insects (it would be easier in the case 
of a multiplying population, where cells are embe dded in exudate).  Finally the likelihood of 
successful multiplication on the hypantium and infec tion would be extremely low.  In addition, it 
would be necessary that such open flower be ava ilable when these surface polluted fruits are present.  
All this cannot be considered to constitute an evidence. 
Question 20 
Please comment on whether the requirements identi fied in Australia's IRA, regarding disinfection 
treatment of apples in the packing house and the disi nfecting of packing house equipment before each 
Australian packing run, are scientifically justified a nd reasonable?  Are you aware of any reliable 
scientific evidence of E. amylovora from harvested  apples contaminating packing house equipment?  
If so, would such bacteria survive the packing ho use process?  Are you aware of any reliable 
scientific evidence of mechanical transfer in a natural  environment of E. amylovora  from workers' 
hands to susceptible hosts?  (Paras. 4.43-4.47, 4.147, 4.38 6 of New Zealand's FWS;  paras.  855-859 
of Australia's FWS;  para. 37 of the United States' Third Party submission;  R 40 by Australia) 
 WT/DS367/11 
Page 30  
 
  Dr Deckers
: 
 142. Disinfection of the apples in the packing house can reduce potential epiphytic populations of 
EA on the fruits considerably.  Disinfection of th e packing house equipment before each Australian 
packing run has not sufficient scientific base;  it is not at all sure that the EA bacteria would be able to 
survive into the process water within the whole popu lation of other bacteria and fungi.  Mechanical 
transfer of the bacteria in a natural environmen t from workers hand to a susceptible host seems to be 
extremely unlikely. 
Dr Paulin
: 
 
143. The disinfection of apple could be justified wh en arriving in the pack inghouse, if these are 
sourced from orchards showing fire blight symptoms.  In this particular case, external pollution by 
exudate oozing from active symptoms of the disease is possible on near-by fruits.  In addition, it 
cannot be ascertain that fruits with symptoms, as well as trashes infected by the bacteria are not mixed 
with healthy mature fruits during cropping in th e orchard.  These trashes may carry an internal 
inoculum which could "leak" into the water used to wash the fruits, and consequently contaminate the 
fruits to be exported.  I see no scientific eviden ce that the bacterial population will not survive the 
packinghouse process for some times.  Again this is only in the case where fruits are sourced from 
orchards having shown, or still showi ng, active symptoms of fire bight. 
144. Mechanical transfer in a natural environment of phytopathogenic bacteria by worker's hands 
to susceptible host has never been published, or obs erved.  The only case I know of for a bacterial 
disease is for Clavibacter michiganensis  pv michiganensis , a tomato pathogen, which is transferred 
from plant to plant on a row, while the plants ar e hand-trimmed.  In this case the biology of the 
bacteria is completely different (it actively multiplies in the vessels).  Nothing similar for 
E. amylovora . 
Question 21 
Please comment on whether the consideration in Aust ralia's IRA of the risk associated with the 
practice of packing houses leaving orchard wholesa ler waste uncovered and exposed to the elements 
on the premises or in landfills is objective and credible , taking into account the likelihood of this 
situation occurring in packing houses in  Australia.  (IRA, Part B, p. 82 (fire blight);  paras. 4.130 and 
4.419-4.421 of New Zealand's FWS;  paras. 784-785 and 898-900 of Australia's FWS;  and R 100 by Australia) 
 
Dr Deckers
: 
 145. The packinghouses involved in the export of apples from New Zealand should not leave 
waste uncovered and exposed because this fruit wast e can form a risk of contamination for the 
environment.  But this requirement should be incl uded in the standard operating procedures for each 
packing house. 
Dr Paulin
: 
 146. I have personally no idea on the likelihood of the possibility that wastes from fruit packing 
houses be uncovered and exposed to elements, although I imagine it is low as it should be in any well 
organized country.  This being said, it has been proven that low bacterial populations (Hale et al. 
1990 ) sometimes as VBNC (Ordax et al, 2008) may be  present for some times in the calyx of fruits.  
If these fruits were discarded in the open and e xposed to the elements, the decaying fruit could 
constitute a suitable medium for a multiplication of  these low bacterial populations.  They could 
multiply, or resuscitate from the VBNC status, and therefore constitute a potential inoculum
 for near-
by host plants.  It is important to add that E. amylovora cannot constitute the only bacterial population  WT/DS367/11 
 Page 31 
 
 
  on these fruits and, being a poor competitor, E. amylovora has good chances to disappear, due to 
trophic competition with other microorganisms (see  question 30 below) on decaying fruits, or to 
antibiosis. 
Question 22 
The likelihood assigned to importation step 1 in Australia's IRA is based on the finding that the 
E. amylovora organism can be present in orchards  even if disease symptoms are not detected, or the 
orchard is surrounded by infected alternative hos ts.  (IRA, Part B, pp. 53-54; para. 4.210 of 
New Zealand's FWS;  paras. 379-382 of Australia's FWS)  a. What is the scientific basis cont ained in the IRA for this finding?  
 
Dr Paulin
: 
 147. The assumption that E. amylovora  can be present in orchards even if disease symptoms are 
not detected (I suppose the same year) is based on th e fact that the bacterium, once it has infected a 
plant, may migrate inside the tree
, sometimes in the xylem, or in peripheric tissues (inner bark).  At 
the end of the growing season, the downward pr ogression stops, and a canker is formed, which may 
be "determinate" or "undeterminate" (in other word visible, or invisible).  The bacteria will remain 
alive in these cankers in winter, and sometimes (but not always) show a new multiplication in the 
tissues and a production of ooze, providing inoculum for new infections in spring.  This cycle is well 
known (Thomson, 2000):  it may result in the presence of undetected bacterial population in the 
trunks and branches.  This population though are unlik ely to pollute the fruit surface, being internal 
into the tree. 
148. Another source of bacteria in a healthy orchar d could be through wind-driven rain or insects 
or birds carried bacteria constituted by ooze fro m near-by (but possibly unseen) "alternative" host 
plants such as wild hawthorn, which may be difficu lt to survey, and which presence is sometimes not 
even acknowledged.  These bacteria will disappear soon, because E. amylovora is not a good 
epiphyte, in most of the cases, but they may cause late infection  which, progressing slowly if weather 
conditions are not conducive to symptom expre ssion, may constitute a bacterial population in a 
symptomless orchard.  These two possibilities are proba bly more likely in the case of New Zealand, 
where the history of fire blight is very long on the same sites.  (The Europ ean concept of "protected 
zone" is probably not ap plicable in this case.) 
Dr Sgrillo : 
 149. The detection of fire blight in  New Zealand both from orchards with fire blight symptoms and 
those without symptoms.
13 
b. Is this finding based on respected and qualified scientific sources? 
 
Dr Paulin : 
 150. These two possibilities are well documented.  It is more difficult to assess the frequency of 
such (provisionally) hidden bacterial populations, and of their real importance and role. 
                                                     
 
13 (footnote original ) IRA p. 53. WT/DS367/11 
Page 32  
 
  Dr Sgrillo
: 
 151. Yes, the findings are based in respected and qualified scientific source (Clark et al., 1993).
14  
However, the objective of this paper w as to test a DNA approach to identify E.amylovora .  The 
objectives have not included a survey of the fire blight populations in New Zealand. 
c. Please comment on whether the reasoning articul ated by the IRA on the basis of such scientific 
evidence, including the methodologies applied, is objective and coherent, and whether the particular conclusions drawn in the IRA find sufficient support in the available scientific evidence? 
 
Dr Paulin
: 
 
152. The reasoning seems objective and coherent.  E ach stage is based on scientific evidence. 
Dr Sgrillo : 
 153. The reasoning is mainly based on the paper of Clark et al. (1993)
15 who presents results from 
evaluations of several seasons.  The 1987 r esults are described by the author (p. 62): 
"In 5 orchards (A-E) where fire blight symptoms were seen during inspections at 
flowering, Erwinia amylovora  was detected in the immature fruit samples..." 
"In 2 orchards (F and G) with no fire blight symptoms at flowering Erwinia 
amylovora  was also detected in calyxes of immatu re fruit.  Further inspections at the 
immature fruit stage revealed the presence of infected alternative host in close 
proximity to these orchards.  In 4 other orchards (H-K) with no fire blight symptoms 
at any stage during the season Erwinia amylovora  was not detected using DNA 
hybridization testing method."16 
154. The 1988 results of the sampling are (p.62): 
"In 1988 Erwinia amylovora was detected in  calyx of immature fruit from 3 orchards 
... and further detailed inspection revealed symptoms of fire blight in the orchard" 
155. The 1989/91 results were not considered here  because the natural environment around the 
orchards were artificially changed (the alternative host in the surroundings were eliminated) (p. 62). 
156. The results indicate that Erwinia amylovora  is not present in orchards that have no symptoms 
and are distant from other hosts. 
d. Do the results of the IRA's assessment in this regard suffic iently warrant the challenged 
requirements related to fire blight?  
Dr Paulin
: 
 157. Yes. 
                                                     
 
14 (footnote original ) Exhibit NZ-53:  Clark, R.G., Hale, C.N. and Harte, D. (1993) A DNA approach to 
Erwinia amylovora detection in large scale apple testing and in epidemiological studies. Acta Horticulturae 338:  
59-66. 
15 Ibidem. 
16 Ibidem.  WT/DS367/11 
 Page 33 
 
 
  Dr Sgrillo : 
 158. The IRA's assessment is not sufficiently supported.  Clark et al. (1993)
17 have sampled around 
10 orchards, each year, from 1987 to 1991.  However the representativeness of the sample in time and 
space can not be evaluated.  The sampling methodolog y was not appropriate to survey fire blight 
populations in New Zealand.  Therefore there are li mitations to use the results with this purpose. 
e. In your view, was it methodologically sound fo r the IRA Team not to assess any apple producing 
areas of New Zealand that would be free of E. amylovora? 
 
Dr Paulin : 
 
159. The conclusion that no orchard in New Zealand can be considered free of E. amylovora  seems 
soundly based. 
Dr Sgrillo : 
 
160. No, the results show that it would be possible to find orchards free from E. amylovora  (see 
item c of this response). 
f. Please comment on the probability of 1 contained in  the IRA for the presence of E. amylovora in the 
source orchards for importation step 1.  Does th is probability fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA? 
 
Dr Paulin : 
 161. If the probability of 1 means that all orchards are contaminated by E. amylovora  each year, it 
is probably a mere exaggeration.  For example the fa te of bacterial population in canker is either to 
disappear (Beer, 1978) or to multiply and produce symp toms.  In this later case, the orchard is no 
longer symptomless.  Therefore I would say that each apple orchard symptom-free in New Zealand 
may be temporarily
 contaminated by E. amylovora , not permanently.  Therefore the chance for apples 
to be sourced from orchards harbouring E. amylovora  should be significantly less than one. 
Dr Schrader : 
 
162. The assumption, that orchards in New Zealand are 100% infested with E. amylovora  lacks 
sufficient scientific evidence. 
Dr Sgrillo : 
 163. Probability of 1 means that it is absolutely true that fire blight is present and will always be 
present, in all of New Zealand orchards.  The sci entific evidence presented in IRA does not guarantee 
that this is true. 
                                                     
 
17 (footnote original ) Exhibit NZ-53:  Clark, R.G., Hale, C.N. and Harte, D. (1993) A DNA approach to 
Erwinia amylovora detection in large scale apple testing and in epidemiological studies. Acta Horticulturae 338:  
59-66. WT/DS367/11 
Page 34  
 
  Dr Deckers (Response to whole question)
: 
 164. Epiphytic contamination of the apple fruits is possible, even when there is no EA present in 
the orchard itself, but when active EA infections are present on a host plant in the surroundings.  In 
the PhD work of Schouten (Studies on fire blight , 1991, Landbouw universite it Wagenigen, promoter 
Dr J.C. Zadoks) the role of Crataegus  hedges was discussed as a possible infection source around 
pear orchards.  When there is really no EA in fection present in the orchard or in the immediate 
surroundings, it will not be possible to isolate EA bacteria from the fruits.  The bufferzones around the 
orchard that should be free of EA host plants are comparable with the bufferzones around the fruit tree 
nurseries for the fire blight control. 
Question 23 
What is the relevance of importation step 1 (presence of E. amylovora in the source orchard) for the 
risk assessment contained in Australia's IRA in light of the fact that importation step 2 aims to assess 
the likelihood of picked fruit being infested/infected with E. amylovora? 
 Dr Deckers
: 
 165. The presence of a fire blight in the orchard in creases the risk of epiphytically contaminated 
fruits in the immediate neighbourhood of the infection.   One fire blight infection in an orchard does 
not mean a complete contamination of all the fruits of the orchard. 
Dr Paulin
: 
 
166. In my view, relevance of step 1 is major  for the risk assessment.  Step 2 assesses likelihood of 
contamination of fruits.  This like lihood is directly related to the hi story of fire blight the year of 
cropping (presence or not of active symptoms producing inoculum) and the years before (possibility of internal presence of E .amylovora  in the xylem.  Even if this possibility has very little chance to 
result in internal fruit contamination (especially in  mature symptomless apples), these chances are nil 
if fire blight has not been seen in  the orchard for years (or ever). 
Dr Sgrillo
: 
 167. IRA does not present results of the sensitivity an alysis of the model.  Thus the relative 
relevance of each step in estimating the probability of importation can not be assessed. 
168. If the probability of step 1 is set to 1, then this step is unnecessary and could be removed from 
the model.  However the model was developed to be  applied by different pests that may not have 
probability 1 in this step, such as N. Galligena.
18 
169. Also, step 1 could be included in step 2.  Th e probability of the fruit picked be infested could 
be assessed including the probability of the pest be  present in the orchard.  In this case, however, 
some transparency would be lost. 
Question 24 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of 1 x 10E-3, a maximum value of 5 x 10E-2 and a most 
likely value of 3 x 10E-2) for importation step 2 (the  likelihood of picked fruit being infested/infected 
with E. amylovora) sufficiently suppor ted by the available scientific evidence?  
 
                                                      
18 (footnote original ) IRA p. 118.  WT/DS367/11 
 Page 35 
 
 
  Dr Sgrillo : 
 170. The figures available are contradictory and variable
19.  The IRA (pg 55) recognizes the 
contradictory nature of the available data: 
"The available literature in the context of this assessment is divided;  some data 
supports the presence of E. amylovora  as infestation (external) or infection (internal), 
while other data supports its absence from fruit". 
171. The IRA Team has chosen a triangular di stribution with the most probable value 
corresponding to 3% infestation.  The scientific  evidence presented in IRA does not guarantee that 
this is true.  By selecting different set of results  it would be possible justify different values for the 
parameters of the distribution. 
Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based 
on respected and qualified scientific sources?  
 
Dr Sgrillo : 
 
172. The papers cited by IRA seem to be qualified.   However, possibly due to the methodology 
used by each author and to the cultivar, place and se ason where the samples were extracted, etc., the 
results are not comparable. 
Does this evaluation fall within a range that c ould be considered legitimate according to the 
standards of the scientific community and the methodology  applied in the IRA?  (IRA, Part B, p. 55-
65;  paras. 4.213-4.220 of New Zealand's FWS;  and para. 391-411 of Australia's FWS)  
Dr Deckers (Response to whole question)
: 
 173. The value of 3 X 10 E-2 seems to be a quite high rate of picked fruit being infected with EA.  
I think there will be more a gradual distribution of presence of the fire blight bacteria on the fruits 
around the EA infections present in the orchards. 
Dr Paulin
: 
 174. I consider that it is just not possible to provide a probability range from the scientific data 
taken into account in this discussion.  Each paper deals with its own type of fruit (mature or not, 
sometimes not precisely indicated), its own technique of detection of the bacteria, etc...  No general 
feature for the presence of E. amylovora  on/in mature apple fruit can be seriously based on these 
results.  The range of frequencies indicated on the table 4 from AUS FWS (from <1% to 75%) just 
shows that, in these papers, different things were an alysed differently.  Consequently, it could be not 
valid to aggregate these technical data.  Therefore,  I am in the opinion that this evaluation is not 
scientifically based , cannot be objective and, as shown on table 4, is just not credible as a whole. 
175. Most of the scientific sources are respected and credible.  Nevertheless, the van der Zwet et 
al.,1990, paper which is criticized by its own first au thor should have been removed from the list.  
Other data, such as in the paper from Sholberg et  al, 1988, seems to be very specific, and could 
represent but a case history , which was probably very different fro m a normal situation, that would be 
an orchard devoted to export of apples.  The paper on bacteria in seeds and ovule (Mundt and 
Hinkle,1976) does not provide any proof that E. amylovora  is present in seeds of apple;  which is 
worse it does not provide clues as to th e identity of isolated bacteria with E. amylovora .  On the other 
                                                      
19 (footnote original ) IRA pp. 55-64. WT/DS367/11 
Page 36  
 
  hand the mechanisms described for  E.  amylovora conservation (EPS, VBNC, quorum sensing, sigma 
factors) do show accurately that E. amylovora  cells may survive in adverse conditions
, including on 
apples sourced from contaminated orchards.  Bu t this information does not allow a quantitative 
evaluation.  It indicates that these surviving popula tions are of low level, that their capacity of 
resuscitation (VBNC) is possible but not demonstrat ed in natural conditions.  Anyhow these surviving 
cells can be expected to be less if the apples ar e sourced from orchards without active symptoms, if 
the apples are symptomless, if no trashes are mixed with mature symptomless apples. 
Question 25 
Please comment on the following statement in Australia 's IRA:  "Given the widespread distribution of 
fire blight in New Zealand, the IRA team concluded that more weight should be given to those studies 
on apples sourced from orchards that were showi ng symptoms of fire blight disease".  Is this 
statement based on an objective and coherent reasoning?  (IRA, Part B, p. 65;  para. 385 of Australia's FWS;  and para. 65 of the United States' Third Party submission) 
 
Dr Deckers
: 
 
176. This statement doesn't take into account the sporad ic character of the fire blight disease in an 
infected orchard;  this means that one year with EA infection will alternate with years with a much 
lower fire blight incidence;  there will also be  years without EA symptoms even in an infected 
orchard.  It is important to mention here that also the other host plants should be observed for a 
possible presence of EA infections. 
Dr Paulin : 
 177. It is coherent to assume that no orchard in New Zealand is or has been permanently free of 
fire blight.  That does not mean that all orchards  permanently show active symptoms.  Therefore it 
seems that orchards in New Zealand should be considered as a patchwork
 of orchards with symptoms, 
and orchards showing no symptom.  Then I do not see why more weight should be given to one 
category (with symptom) only.  All the studies, weighted according to their own scientific value  
should be considered with the same level of interest .  The exact fire blight situation of these orchards 
analysed in these papers and the re levance of the techniques used should be the criteria, if some of 
them were to be selected as more important than others. 
Dr Sgrillo : 
 
178. More weight should be given to studies with  more reliable methodology and with more 
representative sampling.  A sample of 30,000 fruits from several orchards is more reliable than a 
sample of 100 fruits from a single orchard, artificially inoculated, regardless of their results. 
Question 26 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of 1 x 10E-3, a maximum value of 3 x 10E-2, and a most likely value of 1 x 10E-2) for importation step 3 (the likelihood of contamination by E. amylovora during picking and transportation to a packing house described in importation step 3) 
sufficiently supported by the available scientific evidence? 
  WT/DS367/11 
 Page 37 
 
 
  Dr Sgrillo : 
 179. The scientific evidence is scarce, coming mainly from two papers.  One by van der Zwet et al. 
(1990)
20 says that: 
"Only 3 of 72 uninoculated and non-disinfest ed fruit developed blight symptoms - all 
through injury in the puncture treatment". 
180. The IRA Team calculated that 4%  (3/72) of the fruits damaged wo uld be contaminated by fire 
blight21.  The reliability of this result is low because th e sample size was small, the variability was not 
assessed and the results are valid only for artificially injured fruits. 
181. The other paper by Hetzroni et al. (2004)22 is a four paragraph abstract that says: 
"The results show that at the time of the first check, the percentage of damaged apples 
was the lowest in the careful picking treat ment: about 8% compared with 37% in the 
whole container in the packing house". 
182. This abstract is also poor in details about the methodology and analysis of the results. 
183. The 4% (0.04) figure was then multiplied by 37% (0.37) to obtain an indication of the 
magnitude of the most probable value of the triangular distribution used.23 
184. The conclusions of the IRA are not well supported.   Considering the small sample size used in 
the first paper and the lack of information on the methodology and on the details of the results of the 
second paper, the soundness of the scien tific support is not well defined. 
(ii) Is this evaluation objective and credible on th e basis of the available scientific evidence? 
Dr Sgrillo : 
 
185. The evaluation is objective, but the available scien tific evidence is not sufficient to support it. 
Is it based on respected and qualified scientific sources?  Does this evaluation fall within a range that 
could be considered legitimate according to the standards of the scientific community and the 
methodology applied in the IRA?  (IRA, Part B, pp. 65-71;  paras. 4.221-4.224 of New Zealand's 
FWS;  and paras. 412-413 and 439 of Australia's FWS)  
Dr Deckers (Response to whole question)
: 
 186. The likelihood of contamination by EA during pi cking and transportation is possible when the 
harvest takes place in a heavy infected orchard durin g rainy circumstances, but the overall chance of 
1% seems to be rather high when the fire blight in fections are only sporadically present in an orchard. 
                                                     
 
20 (footnote original ) Exhibit AUS-31: van der Zwet T, Thomson SV, Covey RP and Bonn WG (1990) 
"Population of Erwinia amylovora on external and internal apple fruit tissues", Plant Disease 74(9): 711-716 (p. 713). 
21 (footnote original ) IRA p. 70. 
22 (footnote original ) Hetzroni, A., A. Bechar, I. Nir, A. Antle r, S. Yosef, N. Sham ir 2004. Mechanical 
injuries in Apples. Retrieved 24 January  2009, from  http://old.agri.gov.il/AGEN/ Reports/hetzroni003.html. 
23 (footnote original ) IRA p. 70. WT/DS367/11 
Page 38  
 
  Dr Paulin (Response to whole question)
: 
 187. The available scientific evidence shows that E. amylovora  is not a true "epiphyte", hence it 
cannot multiply, but only survive, with decreasing  population on contaminated surfaces.  It could 
multiply, and then maintain a high level of population, only if it were able to infect the plant.  On a 
mature fruit this possibility of infection does not exist.   Mature fruits are then concerned only at best 
with transient populations, which are likely to be  soon disappearing.  In addition, these transient 
populations would be present in the case where active , ooze producing fire blight lesions are present 
in the orchard at, or just before, picking time. Such a condition seems easy to avoid. 
188. Therefore mature symptomless fruit will not bring in a packing house significant population 
of E. amylovora  on their surface.  Consequently, the evaluati on of risk for this step seems too high, 
for mature symptomless fruits.  Decaying fru its and trashes would represent a higher risk. 
Question 27 
Please comment on whether the reasoning in Austra lia's IRA regarding the number of E. amylovora 
bacteria isolated from, and reported on, mature apple fruit that would be sufficient to spread to a 
susceptible host and initiate an infection under natural (as opposed to laboratory) conditions.  Is this 
evaluation objective and credible? Is it based on respected and qualified scientific sources? (IRA, 
Part B, p. 69-70;  para. 4.224 of New Zealand's  FWS;  paras. 361-362 and 418 of Australia's FWS) 
 
Dr Deckers
: 
 
189. The chance that the epiphytic b acteria that can be present on mature apple fruits initiate an 
infection on an other host plant will be very low.  Th e critical point will be the transfer of viable EA 
bacteria to susceptible organs of an other host pl ant where the bacteria can multiply before a new 
infection can take place. 
Dr Paulin : 
 
190. The number of 38 cells needed to initiate an in fection on apple shoot, as obtained by Crosse et 
al., 1972, seems a soundly established basis for the minimal number of cells able to initiate an 
infection, when introduced artificially at the proper s ite of the suitable plant, in optimal conditions for 
the disease.  Unfortunately it gives very few useful indications  for the description of events taking 
place in natural conditions.  It has to be noted that  the 38 cells reported by Crosse et al. were issued 
from a culture on artificial medium:  they were actively growing cells , not dormant cells at the 
stationary stage as would be bacterial cells survivin g on apple surface.  It has to be reminded that 
E. amylovora  is not able to multiply on plant surface (e xcept for a short time, on the hypantium of 
stigmates in flowers).  It is difficult to imagin e conditions conducive to actively growing cells in 
natural conditions on the surface of a symptomless apple. 
191. The spread of surface population from fruit to infection sites is similarly hard to imagine, 
especially because these non-multiplying cells are not embedded in exudate, and therefore not attractive to insects or other vectors.  In artificial inoculations, bacterial populations at low level need 
to be placed very precisely
 at the right site of infection, to su ccessfully infect its host plant (Crosse et 
al.).  This is probably a difficulty impossible fo r the bacteria to tackle in natural conditions. 
Question 28 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of 0.3, a maximum value of 0.7, and a most likely value of 0.65) for importation step 4 (the likelihood th at E. amylovora would survive routine processing 
procedures in the packing house) sufficiently s upported by the available scientific evidence? 
  WT/DS367/11 
 Page 39 
 
 
  Dr Sgrillo : 
 192. Australia's IRA states that "None of the processes [routine processing procedures in the 
packing house] undertaken at this stage would have a large influence on the survival of E. amylovora  
on apple fruit".
24 
193. However this statement is not compatible  with papers cited by IRA, as follows. 
"Maas Geesteranus and de Vries (1984) refer to reduced survival in pre-cooling."25 
"Roberts and Reymond (1989) and Goodman (1983) showed the efficacy of washing 
in removing infestation of E.amylovora ".26 
"Toivonen et al. (2001) showed that sodi um hypochlorite (100 µg per liter) or 
peroxyacetic acid at 80 ppm was fully effective in eliminating micro-organisms from 
the surface of apples".27 
"Janisiewicz and van der Zwet (1988) reported that 12 mg per L of sodium 
hypochlorite in vitro totally eradicated E. amylovora  in 5 minutes".28 
"Roberts and Reymond (1989) artificially inoculated mature apple fruit with 
E. amylovora aerosol solutions (8.0 x 106 to 1.3 x 108 per fruit) and immersed fruit in 
different concentrations (250, 300, 400, 500 ppm) of sodium hyp ochlorite or 1.0 M 
acetic acid.  The reduction in the E. amylovora  population averaged 6 to 7 log units 
less than the number applied to the fruit, but significant differences between treatments were not observed".
29 
"Sholberg et al. (1988) inoculated fru it by swabbing calyces of apples with an 
average of 107 cfu per mL of E. amylovora .  These authors demonstrated that the 
initial population decreased to an undetectable  level after 6 months in cold storage".30 
194. Also IRA refers that "Sorting and grading to  remove visibly damaged fruit would reduce the 
number of apples potentially carrying infections".31 
195. IRA mentions that 90% of the crop in New Zealand is submitted to pre-cooling treatment 
routinely and that 37% of packing houses use chlorine in the dump tank with the concentration that 
varies between 5 and 50%.  Also 16% of pack ing houses uses peroxyacetic acid (Tsunami®), and 
bromo-chloro-dimethylhydantoin (Nylate ®), which totalize 53% of packing houses being disinfected.
32 
                                                      
24 (footnote original ) IRA p. 76. 
25 (footnote original ) IRA p. 71. 
26 Ibidem. 
27 (footnote original ) IRA p. 72. 
28 (footnote original ) IRA p. 71. 
29 (footnote original ) IRA p. 73. 
30 (footnote original ) IRA p. 75. 
31 (footnote original ) IRA p 74. 
32 (footnote original ) IRA pp. 71-72. WT/DS367/11 
Page 40  
 
  196. If it is accepted that the epiphytic population of E. amylovora  is reduced/removed by pre-
cooling
33 and disinfection treatment then the survival in the packing houses would be 0.047 [(1-0.9) * 
(1-0.53)] that is much less than the minimum value of 0.3. 
197. Australia states that "Given the risk  scenario addressed by the IRA Team, E. amylovora  will 
be taken to have survived this step even if only one bacterium  survives routine pack house procedures 
on any given apple".34 
198. It is implicit in the above statement the acceptance of the hypothesis that fruit with 1, 10 or 1 
million bacteria has exactly the same probability of initiating an infection . 
199. However, for the majority of plant pathogens, th is is not true.  Usually a number of conditions 
have to occur simultaneously to allow infection.  The probability that an infected fruit, with one 
bacterium, starts an infection is different from th e probability of a fruit that is infested with 10,000 
bacteria.  It is known that the probability of establishment is a function of the initial population size.35 
200. The dose-response curve may present a threshol d for the inoculums concentration, below 
which no infection will occur.  We can read in IRA: 
"Van der Zwet et al. (1994) showed that five bacteria were sufficient to cause fire 
blight symptoms in apple flowers in one season, but in another season a minimum of 
5000 bacteria per blossom were required for infection to occur".36 
… "Experiments were conducted in New Zeal and (Hale et al., 1996) to determine the 
number of E. amylovora  cells required to infect apple and cotoneaster flowers.  These 
authors reported that when flowers were inoculated with 1 to 10
4 cfu per flower, there 
were no disease symptoms and E. amylovora  was not detected.  Fire blight symptoms 
were only observed when the inoculum dose of E. amylovora  exceeded 106 cfu 
(Taylor et al., 2003b).  Such populations may exist in fruit from heavily infected orchards, but not in fruit from lightly infected or symptomless orchards (Hale and Taylor, 1999).  Similar observations we re made by Beer and Norelli (1975), who 
reported that infections are likely to occur when epiphytic populations of 
E. amylovora  reached 10
6 to 107 cfu under high relative humidity and not at 
102 cfu"37. 
201. If it is accepted that there is a relationship be tween the dose of inoculum and the probability 
of starting a new infection then the decrease of quantity of inoculum may be enough to break the 
pathogen cycle, having the same effect as  the total elimination of the inoculum. 
202. It can be concluded that the scientific eviden ce available does not fully support the values 0.3, 
0.65 and 0.7 chosen as parameters for the tria ngular distribution describing the survival of 
E. amylovora  during the routine processing procedures. 
Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based 
on respected and qualified scientific sources?  Does this evaluation fall within a range that could be 
                                                      
33 (footnote original ) New Zealand's FWS para. 4.226. 
34 (footnote original ) Australia's FWS para.  421. 
35 (footnote original ) Reference 01 Liebhold, A.M., W.L. Macdonald, D. Bergdahl, and V.C. Mastro. 
1995. Invasion by Exotic Forest Pests: A Threat to Forest Ecosystems. Forest Science Monographs 30. 49 pp. 
36 (footnote original ) IRA p. 88. 
37 Ibidem.  WT/DS367/11 
 Page 41 
 
 
  considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  (IRA, Part B, p. 71-76;  para.  4.225 of New Zealand's FWS;  and paras. 419-420 
of Australia's FWS) 
 
Dr Sgrillo : 
 
203. Part of the evaluation is objective and credible , based on qualified scientific sources and falls 
within a range that could be considered legitimate.   However the values chosen for the parameters are 
not supported. 
Dr Deckers (Response to whole question) : 
 
204. The disinfection process during packaging should re duce the risk of surviv al of the epiphytic 
population strongly and reduce the distribution patter n substantially.  But a total removal of the 
bacterial population will not be an easy task. 
Dr Paulin (Response to whole question) : 
 
205. If routine procedure in New Zealand packing ho uses does not include a disinfectant bath for 
fruits, I do not see which factor could effectively markedly decrease the supposed bacterial population 
on fruit surface.  I would then consider that pr ocessing in the packing house has no influence on the 
level of bacterial contaminants on fruits.  The scien tific bases of the IRA conclusions are data on the 
resistance of E. amylovora  in adverse conditions, such as low temperature and dessication.  It seems 
that most data tend to show that cool temperature will reduce E. amylovora  populations over time.  
Anyhow, it will never be possible to extend results obt ained with artificial infestation of fruits to 
actual bacterial population naturally placed on certain sites on the fruits.  It seems certain that, if 
conditions in the packing house tend to reduce E. amylovora  population, they will not allow the 
complete disappearance of these bacteria.  The fact  that VBNC state has been demonstrated in 
laboratory conditions for E. amylovora  adds a potential for survival (whatever the frequency of cells 
at the VBNC state, and the chance of resuscitati on, which is controversia l in natural condition). 
206. Conversely, if a disinfectant step is included in the process, the decrease of the level of 
bacterial population can be expected to be sharp.  Nevertheless, it will never be possible to prove that 
a chemical disinfection procedure of biological ma terial is always 100% safe in natural conditions. 
207. Therefore, in the case of fruit disinfection, the probability range and pattern distribution for 
this step seems too high for this step.  This applies for mature symptomless apples, but would not be 
different for trashes associated with fruits. 
Question 29 
Australia's IRA considers the impact of cold st orage and cold conditions  on populations of 
E. amylovora under importation steps 4 and 6.  Please comment on the reasoning in the IRA 
regarding these matters (including whether cold  storage will greatly decrease populations of 
E. amylovora on mature apple fruit, whether cold temperatures prolong the survival of E. amylovora 
bacteria on mature apple fruit and whether there is  a time limit at which E. amylovora bacteria 
populations on mature apple fruit decline to undetect able levels under cold storage temperatures).  Is 
this evaluation objective and credible? Is it based on respected and qualified scientific sources?  (IRA, Part B, pp. 71-76;  para. 424 of Australia's FWS;  and para. 67 of the United States' Third 
Party submission)  WT/DS367/11 
Page 42  
 
  Dr Deckers
: 
 208. Cold storage of the fruits will reduce the bacter ial population of EA on the fruits but will not 
eliminate the EA populations on the fruits completely.  In principle the EA bacteria can easily survive 
a cold storage period. 
Dr Paulin
: 
 209. Data on preservation of bacterial population on apple surface during cold storage seems to 
accurately show that there is a decr ease in these conditions.  It is not possible to know if this decrease 
is linked with temperature, or only with time:  because bacteria are not able to multiply, their 
population decreases naturally, and this decrease could be  faster at room temperature;  in the precise 
case of risk of transport of bacteria with mature symptomless fruits anyhow, this has little influence:  
the conditions in the packing house will not allo w the population to increase, but will not allow the 
population to disappear within the considered period of time (few days?).  Especially because of the 
possibility of VBNC, a time limit can not be accura tely determined for the maximal survival of 
E. amylovora.  
Question 30 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of 1 x 10E-3, a maximum value of 5 x 10E-2, and a most likely value of 2.5 x 10E-2) for importation step 5 (the likelihood that apples entering packing houses free of E. amylovora become contaminated  during processing) sufficiently supported by the 
available scientific evidence?  
Dr Sgrillo
: 
 210. IRA states:  "Ceroni et al. (2004) immersed  pear fruit for 15 min in a suspension of 
E. amylovora  of 10
8 cfu/mL and could not detect bacteria on the surface after just a few days, with 
small numbers remaining for longer periods only in the calyx.  These authors concluded that bacterial 
survival on the fruit surface is very short and has a negligible epidemiological role.  If E. amylovora  
gets into the core in the dump tank, one would expect  some internal infection to develop but this has 
never been reported. "38 
211. Considering that 108 cfu/mL is 106-107 folds higher39 than the expected concentration in the 
dump tanks then the probability that apples become infested during processing should be negligible.  
However IRA concludes that 2.5% (most probable va lue) of the fruits would be contaminated during 
process. 
212. IRA informs in Summary of step 5: 
"This conclusion [shape and parameters of the distribution] was based on the 
potential for the fruit dump tank to become contaminated by bacteria and the fact that 
disinfection of the dump tank water is not a routine practice in a significant number of New Zealand packing houses".
40 
213. The scientific evidence presente d in IRA does not guarantee the probability range chosen. 
                                                      
38 (footnote original ) IRA p. 78. 
39 Ibidem. 
40 Ibidem.  WT/DS367/11 
 Page 43 
 
 
  Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based 
on respected and qualified scientific sources? 
 
Dr Sgrillo : 
 
214. The scientific sources are qualified but do not support the conclusions of IRA. 
Does this evaluation fall within a range that c ould be considered legitimate according to the 
standards of the scientific community and the methodol ogy applied in the IRA?   Does it take into 
account available scientific evidence of E. amylovor a contamination of mature apple fruit by packing 
shed machinery?  (IRA, Part B, p. 77-79;  pa ra. 4.228 of New Zealand's FWS;  and para. 439 of 
Australia's FWS)  
Dr Deckers (Response to whole question)
: 
 215. This step in the IRA is not sufficiently in accordance with the standards of the scientific 
community and the chance that this contamination of apples entering free of EA happens during 
processing is neglectible when the wa ter during processing is disinfected. 
Dr Paulin (whole question)
: 
 216. The liquid medium (in which mature sympto mless apple fruits are immersed during the 
process), even without disinfectant, can not be considered as a culture medium for  E. amylovora :  an 
artificial medium for such bacteria must content am ong other elements a rather high level of soluble 
sugar (0,5g/l is a minimum, 5g/l is th e standard for a culture medium for  E. amylovora ).  Therefore it 
is rather a dilution effect that could be expected fro m this step.  In this particular case, the probability 
suggested in the IRA seems to be strongly exagge rated.  Only if decaying apples (supposedly 
decaying from E. amylovora  infection-then immature and not "symptomless") or large amount of 
infected trashes, were present, the dilution eff ect in a non-disinfectant medium could lead to a 
significant amount of bacterial cells on fruit surf aces.  This seems very unlikely in practical 
conditions. 
217. The scientific evidence is that, in artificial medium E. amylovora  does not compete very 
successfully against natural antagonistic bacteria (such as Pantoea agglomerans  or 
Pseudomonas fluorescens,  Vanneste, 2008), which are naturally found in high concentration on plant 
and on fruit surface, and which would compete with E. amylovora , thus preventing a multiplication of 
E. amylovora , if present.  Finally I would therefore consider that the risk of contamination of apples 
by packing shed mach inery is negligible. 
Question 31 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of value of 0.7, a maximum value of 1, and a most 
likely value of 0.8) for importation step 6 sufficien tly supported by the available scientific evidence?  
Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based 
on respected and qualified scientific sources?  Does this evaluation fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  Are such likelihood values based on a finding in the IRA that E. amylovora could 
survive in epidemiologically significant num bers after palletisation, quality inspection, 
containerisation and transportation of apple fruit to Australia?  If so, is such a finding based on respected and qualified scientific sources?  (IRA, Part B, p. 79;  para. 4.229 of New Zealand's FWS;  
and paras. 361 and 431-432 of Australia's FWS) 
 WT/DS367/11 
Page 44  
 
  Dr Deckers
: 
 218. The survival of the EA bacteria during palle tisation, containerisation and transport is 
considered to be low, surely after the external di sinfection of the fruits during the packaging process.  
The cold storage itself will not be able  to eliminate EA populations completely. 
Dr Paulin
: 
 219. The supposition made by the IRA relies on the evaluation of the survival of E. amylovora , 
during a short period (10 days), which is expected  to provoke but a small decrease in bacterial 
populations.  It seems reasonable to take this period into consideration, because it seems agreed that it 
corresponds to the minimum of time  needed for New Zealand-Australia journey.  In practice, the 
period could be longer, and therefore the expected  decrease could be a little more, but this does not 
need to be considered further.  At any rate it ca nnot be relied upon this period of expected decreasing 
survival to secure a "sterilisation" of supposedly c ontaminated fruits.  The evaluation IRA for this step 
seems correct. 
Question 32 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of 0, a maximum value of 1 x 10E-6, and a most likely value of 5 × 10E-7) for importation step 7 (the likelihood of clean fruit being contaminated by 
E. amylovora during palletisation, quality inspection,  containerisation and transportation) sufficiently 
supported by the available scientific evidence?  Is this evaluation objective and credible on the basis 
of the available scientific evidence?  
Dr Sgrillo
: 
 220. The scientific evidence is scarce and the IRA is not fully supported by it. 
221. The conclusions of the IRA are based in th e paper from van der Zwet et al. (1990).
41 
"Such fruit (with bacteria oozing) are rarely found (van der Zwet et al., 1990), as 
rotten fruit is not harvested.  If harvested, su ch fruit is rejected before entering the 
packing line.  If rotten fruit is present afte r cold storage, it is discarded at quality 
inspection".42 
222. From the citation above it can be concluded that  the final probability of step 7 is composed 
mainly by three partial probabilities:  the probability of a rotten fruit be harvested;  the probability of a 
rotten fruit entering the pack line and the probabilit y of a rotten fruit pass the quality inspection. 
223. If the final probability is taken to be 1E-6 ( as the maximum value) then each of the three 
partial probabilities (if they are assumed to be equa l) would have the value of 0.01 (because 0.013 = 
1E-6).  This is equivalent to accept that 1% of the rotten fruit would be harvest and that 1% of the 
rotten fruit harvested will enter th e packing line and that 1% of th e rotten fruit w ill pass the quality 
inspections.  One percent seems to be a very larg e proportion for events that actually would have a 
negligible probability of occurrence. 
                                                      
41 (footnote original ) Exhibit AUS-31:  van der Zwet T, Thomson SV, Covey RP and Bonn WG (1990) 
"Population of Erwinia amylovora on ex ternal and internal apple fruit tissues ", Plant Disease 74(9):  711-716. 
42 (footnote original ) IRA p. 79.  WT/DS367/11 
 Page 45 
 
 
  224. However if the three partial probabilities are taken to be negligible (according to IRA 
definition: 1E-6 as maximum value) then the maxi mum value for the probability of step 7 would be 
1E-18 (1E-63) what is practically equal to zero. 
(iii) Is it based on respected and qualified scientific sources? 
 
Dr Sgrillo : 
 225. The scientific source is qualified but is not ade quate to support the conclusions in the IRA. 
Does this evaluation fall within a range that c ould be considered legitimate according to the 
standards of the scientific community and the methodology applied in the IRA?  (IRA, Part B, p. 79;  
para. 4.232 of New Zealand's FWS;  and para. 438-439 of Australia's FWS)  
Dr Deckers (Response to whole question)
: 
 226. This risk is neglectible.  There is no scientific  data available that demonstrate the risk of 
contamination during palletisation, quality insp ection, containerisation and transportation. 
Dr Paulin (Response to whole question)
: 
 227. In its analysis of this step, IRA does not provi de any scientific eviden ce that such external 
pollution can happen, except in the case of oozing fruits.  It referred to van der Zwet 1999 paper, 
which has already been considered as not providi ng the correct information on the case, which the 
author recognizes himself.  In addition, internally  infected fruits immature producing ooze, if any, 
would have been discarded well before this step. 
228. I would consider the probability to be nil in this case, for symptomless mature apples. 
Question 33 
Please comment on the evaluation in Australia's I RA at importation step 7 of the risk of surface 
contamination of mature clean fruit on an expor t packing line through bacteria oozing out from 
internally infected fruit.  Is this evaluation objective and credible on the basis of the available 
scientific evidence?  Is it based on respected and qual ified scientific sources?  Please comment in this 
regard on the conclusions reached in the 1990 study by van der Zwet et al and their relation to mature fruit.  (IRA, Part B, p. 79;  para. 4. 215 of New Zealand's FWS;  and para. 70 of the 
United States' Third Party submission) 
 
Dr Deckers
: 
 229. Internally infected mature fruits will not be ab le to produce bacterial ooze.  These fruits will 
immediately be invaded by fungal infections.  Oo ze production occurs only on immature fruits where 
the starch of the immature fruits is used by  the EA bacteria during the multiplication phase. 
Dr Paulin
: 
 230. Ooze can only be produced following a progr essive invasion of susceptible tissue by the 
bacteria.  Oozing out from mature fruit is not described  in fire blight symptoms.  It could possibly (?) 
happen in the case of a delayed evolution originating from an infection of an immature fruit, but as far 
as I know, this as not been described in the scientif ic literature.  The only scientific basis for oozing 
on mature fruit (?) is from van der Zwet 1990, whic h has already been discussed, and which can be 
considered as irrelevant for the case. WT/DS367/11 
Page 46  
 
  Question 34 
When the various likelihoods from importation st eps 1-8 are inserted into the IRA's risk simulation 
model, the probability of importation of E. amylovora is estimated as  being 3.9 x 10E-2 (mean), 2.2 x 
10E-2 (5th percentile) and 5.6 x 10E-2 (95th percentile).  The mean infestation rate for E. amylovora 
is estimated at 3.9% of all apples imported from New Zealand.  Please comment on whether the IRA's 
conclusion on the probability of importation of E. am ylovora is sufficiently s upported by the available 
scientific evidence. 
 
Dr Sgrillo
: 
 
231. Scientific evidences on the rates of infestation of apples imported from New Zealand are 
scarce. 
232. There are two papers43 that evaluate infestation in mature apples in orchards sampled in New 
Zealand. 
233. Hale et al., 198744 says: 
"E. amylovora  was isolated only from 3 of 400 fruits (cv. Gala) harvested from the 
severely infected orchard.  In each instance E. amylovora  was detected only in 
washings from the calyx-end.  E. amylovora  was not isolated from 1300 fruit (cv. 
Gala) harvested from 2 lightly infected orchards and 3 orchards where no fire blight symptoms were seen." 
234. Hale and Taylor (1999)
45, who evaluated the infestation of E.amylovora  in orchards with and 
without fire blight symptoms, describe: 
Fruit from orchards with fire blight symptoms - E.amylovora  was detected in 2% of 
fruit before cool storage but not in any fruit after either cool storage, or cool storage and incubation.  E. amylovora  was not isolates from any fruit tested.  Fruit from 
orchard without fire blight symptoms - E. amylovora  was neither detected in, nor 
isolated from any of the fruit tested before or after cool storage or after cool storage 
and incubation. 
235. The results of these studies suggest that the leve l of infestation generated by the IRA's model 
(3.9%) is greater than what would occur in reality. 
Please also comment whether these overall probability  results are correct based on the values given 
to importation steps 1 to 8.  (IRA, Part B, p. 80;  para. 4.235 of New Zealand's FWS) 
 
Dr Sgrillo
: 
 236. The overall probability results are correct and based on the values given to the importation 
steps, according to the model presented in Table 4 of the IRA.
46 
                                                      
43 (footnote original ) Australia's FWS para. 398 (Table 4). 
44 (footnote original ) Exhibit NZ-21:  Hale, CN, EM McRae and SV Thomson (1987) "Occurrence of 
Erwinia amylovora on apple fruit in New Zealand" Acta Horticulturae 217, 33-40. 
45 (footnote original ) Exhibit NZ-24:  Hale, CN and RK Taylor (1999) "Effect of cool storage on 
survival of Erwinia amylovora in apple calyxes" Acta Horticulturae 489,139-143. 
46 (footnote original ) IRA p. 24.  WT/DS367/11 
 Page 47 
 
 
  Dr Deckers (Response to whole question) : 
 237. In the IRA risk simulation, they make an add ition of the different risks for each importation 
step and this gives a mean risk of 3.9%.  Th is is a relative high pe rcentage and could be 
overestimated. 
Dr Paulin (Response to whole question)
: 
 238. As explained above, the different steps of im port are of diverse influence on the overall 
probability of importation of E. amylovora .  It seems to me that, if one can speculate or discuss on the 
likelihood of any event involved in the possible transport of E. amylovora  with apples, the 
quantification of probabilities of each one of these events is just not feasible
.  This quantification 
relies on an arbitrary estimation, which, even in the best-documented case, is just hidden behind a 
"scientific" explanation, which is never complete ly relevant, if only because the conditions in the 
laboratory are only partially mimicking natural c onditions.  This quantification of probability may 
have a merit in trying to assess the relative  risks attached to each step , as compared to each other. 
239. The overall figure resulting from the combinati on of these probabilities is just not credible :  if 
the 3.9% figure had any consistency, it is a figure that could be quite easily checked experimentally 
(as is, for example, spread through planting material ).  Such an experiment would have been more 
convincing than the present efforts by IRA to de monstrate what cannot be really demonstrated. 
Question 35 
Please comment on the finding in Australia's IRA that E. amylovora can under natural conditions be 
transmitted to a susceptible host via insects feeding on discarded apples leading to the initiation of a 
fire blight infection.  Is this evaluation objecti ve and credible on the basis of the available scientific 
evidence?  Is it based on respected and qualified sc ientific sources?  Is it based on respected and 
qualified scientific sources?  When undertaking a ri sk assessment, how should potential vectors be 
factored in?  In your view, would a rigorous methodology oblige the IRA Team to disregard a 
potential vector because it has never been shown to  "demonstrate" transmission of E. amylovora?  
Are there respected and qualified scientific sources  to support the position that there may be a 
pathway for the spread of E. amylovora from apples to susceptible hosts by way of "mechanical 
processes" in a natural environment?  (IRA, Pa rt B, pp. 80-90;  paras. 4.22-4.26 and 4.243 of 
New Zealand's FWS;  and paras. 418 and 465-476 of Australia's FWS) 
 Dr Deckers
: 
 240. Feeding of insects on discarded apple fruits is not described in the biological cyclus of EA as 
a factor for the spread of the di sease.  Insects that are more import ant for a possible spread of the 
disease are the pollinating insects because they can tr ansfer the bacteria to a flower where the 
infection can take place.  An insect feeding on a di scarded fruit is not considered to be a normal way 
of spreading the disease between an  infected fruit and an other hos t plant.  The chance that the 
epiphytic bacteria will be transmitted to the suscep tible organs of a host plant on the appropriate 
moment to realise an infection is rather small. 
Dr Paulin
: 
 
241. The fact that E. amylovora  can be transmitted to a susceptible host via insects feeding on 
discarded apples is conceivable through an appare ntly logical succession of events, each of them 
being questionable, but never completely impossible . 
242. Many insects are supposed to be able to transm it the bacteria from a source (ooze) to an host 
plant.  To be of some effectiveness, this shoul d take the bacteria right to the infection site (i.e. stigma WT/DS367/11 
Page 48  
 
  in flower, or young tissue of a growing shoot).  Th at reduces the period of time were this spread is 
effective to full bloom, and to growing periods of shoots:  that is only few weeks
 within a year, even 
taking account of the blossom periods, and growing pe riods of the many diverse host plant of fire 
blight. 
243. As far as insects are concerned, I am in the opinion  that any insect that is able to travel from a 
source of inoculum (drop of ooze) to  an infection site can be considered as a potential vector.  It could 
be considered more dangerous if  it is a pollinating insect, because it goes to the right place, more 
receptive, on the plant, or if it is a browser of fr esh watery tissues.  The list of insects involved in 
E. amylovora  transport is neither complete nor limitative.  It is an assessment of what has been seen, 
or thought to be vectors of the bacteria.  To my  knowledge, there is no specificity between any given 
insect and E .amylovora . 
244. Apart from these general considerations, I see no scientific source that could account for 
mechanical transmission of E. amylovora  from fruits to infection sites. 
Question 36 
Are the values presented in the sectio n of Australia's IRA headed "Exposure" regarding the likelihood 
of transfer of E. amylovora from infested or infected mature apples to a susceptible host plant 
(uniform distribution with a minimum value of 0 and a maximum value of 1 x 10E-6) sufficiently 
supported by the available scientific evidence?  (IRA,  Part B, pp. 85-90;  paras. 4.249-4.252 of 
New Zealand's FWS;  and paras. 370-371 of Australia's FWS) 
 
Dr Deckers : 
 
245. For this aspect there is no sufficient scientific data available that describes the likelihood of 
this transfer possibility. 
Dr Paulin : 
 
246. In this section only some fragments of events  are supported by scientific evidence.  Very 
often suppositions or speculations are proposed ra ther than certitudes, ju st because these problems 
have never been addressed scientifically (or at least experimentally).  As a consequence, I do not see 
how it is possible to rely objectively on any figu re for the likelihood of this "exposure" step. 
Dr Sgrillo : 
 
247. The literature review presented  by the IRA allowed the development of the hypothesis that 
E. amylovora  can be transferred from a mature apple fruit to susceptible hosts, beginning an infection. 
248. The transfer of E. amylovora , from mature infested/infected fruits to new hosts, would require 
several successive events to o ccur, each with its own partial likelihood, as described in the IRA47. 
249. The arguments are logical but nevertheless there are no reported cases of this event.  Thus the 
scientific evidence presented does not support the c onclusions because there are no factual data to 
validate the hypothesis. 
250. As an exercise to evaluate the conclusions of  the IRA Team it could be given values for the 
partial likelihood of one of the possible paths, as follows: 
(a) Probability that the bacteria  survive in discarded waste 
                                                      
47 (footnote original ) IRA pp. 85-90.  WT/DS367/11 
 Page 49 
 
 
  (b) Probability of the bacteria to retain its viability 
(c) Probability that the inoculum dose is adequate 
(d) Probability that a vector pick the b acteria in sufficient concentration 
(e) Probability that the vector find a host 
(f) Probability that the host is in a susceptible stage 
(g) Probability that the environmental factor be favorable 
251. It can be assigned, as an exercise, the value of  0.01 (1%) as the most probable value of each 
partial probability.  The maximum exposure value w ould be, then, 1.E-14 what is more than 50 
million times lower than 5E-7 (the arithmetic averag e adopted by the IRA team) and practically equal 
to zero.  This would be more appropriate to represen t an event that has never been reported to occur. 
Question 37 
Does the IRA contain an objective and credible analysis, based on respected and qualified scientific 
sources, for a proposition that the introduction of fire blight via mature apple fruit has ever occurred 
or could occur, either experimentally or under natural  conditions or that populations of E. amylovora 
on mature apple fruit could be the source of fire b light infections under natural conditions?  Are you 
aware of any scientific evidence outside of the IRA for such a proposition?  
Dr Deckers
: 
 252. As mentioned earlier there is a possibility that mature apple fruit can harbour viable epiphytic 
EA bacteria.  The step of the transfer from these  infected fruits to the possible host plant stays the 
most critical step and will be difficult to prove. 
Dr Paulin
: 
 253. No, I do not see any objective analysis for that proposition in the IRA.  To be honest , as a 
scientist, I do not think it is possible to experiment in this matter.  I do not know of any scientific 
evidence in this field.  (This does not mean that mature apple fruit may not be a source of fire blight 
infection, of course). 
Question 38 
Please comment on the finding in Australia's IRA that one E. amylovora bacterium or a very limited 
number of such bacteria on the calyx of a matu re apple could be spread to a susceptible host and 
initiate a fire blight infection under natural cond itions.  Is this evaluation objective and credible on 
the basis of the available scientific evidence?   Is it based on respected and qualified scientific 
sources?  (IRA, Part B, p. 88-92;  Australia's FWS paras. 362, 449, and 458-459;  New Zealand's 
FWS paras. 4.14 and 4.244;  and R 63 by the Parties) 
 
Dr Deckers
: 
 
254. To realise an EA infection, there is a need for bacterial multiplication before an infection 
occurs. This multiplication should take place on a suscep tible organ like on the stigma of a flower of a 
susceptible host plant.  The transfer from calyx of the apple to the susceptible organ is the critical step 
in the infection and this transfer chance is rather low. WT/DS367/11 
Page 50  
 
  Dr Paulin
: 
 255. The question basically at issue is the ability of a very low number of E. amylovora  cells (even 
only one), to provoke an infection.  First of all, it could be useful to remind that the experimental 
manipulation of very low level of bacterial popula tions (say less than 100 cfu/ml) is extremely 
difficult to perform with a sufficient level of accuracy .  In order to be sure to actually use this low 
number of cells, it is necessary to use particular stat istical pattern of experiments, or special kind of 
experiments.  Papers suggesting a minimal concentration threshold for infection by E. amylovora  are 
not all really credible in this respect.  If Cro sse and Goodman's paper (1972) seems to establish clearly 
that less than 50 cells in experimental condition have the potential to infect a plant, results obtained in 
the field by van der Zwet (1994) are just techni cal data, indicating how many bacterial cells are 
necessary for an inoculum in the field to obtai n a reasonable frequency of  positive inoculations. 
256. Nevertheless the fact that one (or very few) cell(s) of E. amylovora  may have the potential to 
infect a plant is important for the biology
 of this bacteria, but does not imply that any one cell of 
E. amylovora  in the open has a chance to provoke fire blight on a host plant.  The key-point here is 
that the few cells inoculated in these scientific pape rs are cells at their optimum capacity:  artificially 
grown on suitable medium as pure culture, they are collected during their phase of exponential growth.  All these conditions, always strictly observe d in experiments, maximise the potential of the 
bacterial population.  In natural conditions, the bact erial cells would be placed in far less favourable 
conditions, and the number of cells needed to succeed in  infection could be expected to be far higher.  
Therefore, between a passage of few cells in th e calyx of an imported mature fruit to a suitable 
infection site followed by infection, a stage of mu ltiplication of the bacteria is necessary. (see above) 
257. As a consequence, the probability of bacteria fro m the calyx of mature apple to infect a plant 
supposes many steps.  One only (infectivity of one or  very few cells) is based on scientific evidence, 
but in condition very different from natural conditions. 
Question 39 
Please comment on the finding in Australia's IRA that populations of E. amylovora typically found at 
harvest can survive on apples for periods considerably longer than that needed to import, distribute 
and sell New Zealand apples in Australia when apples are in cold storage.  Is this evaluation 
objective and credible on the basis of the available scientific evidence?  Is it based on respected and 
qualified scientific sources?  (IRA, Part B, pp. 75-76 ;  paras. 4.17-4.19, 4.225-4.231 and 4.242 of 
New Zealand's FWS;  paras. 419-426 and 457 of Australia's FWS) 
 
Dr Deckers
: 
 258. The storage of the apples at low temperature can reduce the epiphytical populations of EA but 
will not eliminate the epiphytic populations of EA in  the calyx of the fruits.  The period of survival 
can be longer than the period necessary for import, di stribution and selling of the fruits in Australia. 
Dr Paulin
: 
 259. This evaluation is based on the fact that cold  temperatures are usually good conditions for the 
conservation of culture of bacteria in the laboratory.   Results of Temple et al (2007) which show that 
bacterial populations keep longer during cold storage (on pears) are therefore not surprising.  Results 
from Hale and Taylor (1999) showing a tendency fo r bacteria to disappear on apple during cold 
storage are apparently conflicting with those of Te mple et al.  But this can be due to different 
conditions and/or different fruit (a pple versus pear).  These two scie ntific results seem both credible 
and objective.  WT/DS367/11 
 Page 51 
 
 
  260. In addition the recent information, that E. amylovora  is able to turn  to the VBNC state under 
certain conditions, which has b een recently checked with E. amylovora  placed in calyx of apples, 
demonstrates that the survival of E. amylovora  (even if the resuscitation in natural conditions is 
unclear for these VBNC) lasts probably longer  than initially assumed.  C onsequently, this evaluation 
by the IRA is objective and  credible.  Even if it remains impossible to quantify the importance of this 
long conservation. 
Question 40 
Please comment on the conclusion in Australia's IRA regarding rapid multiplication of bacteria in 
natural orchard environments.  Is this evaluation objective and credible on the basis of the available 
scientific evidence?  Is it based on respected and qualified scientific sources?  (IRA, Part B, 
pp. 92-93;  para. 4.245 of New Zealand's FWS;   and paras. 470-471 of Australia's FWS) 
 
Dr Deckers : 
 261. The EA bacteria can indeed multiply rapidly but  not on the epiphytic surfaces of the fruits.  
This multiplication can only occur on susceptible orga ns like immature fruitlets or on the stigma of 
the flowers and only when the climatological cond itions (temperature and relative humidity) are 
optimal for bacterial growth.  The question here is if these circumstances w ill be present at the time 
that the fruits from New Zealand arrive in Australia. 
Dr Paulin
: 
 
262. The rapid multiplication of E. amylovora  in natural orchard environment can be observed 
only after infection (or artificial i noculation) of a susceptible host plant.  The values indicated in the 
literature are strictly linked to the conditions in wh ich they are obtained (no nutrient limitation, no 
water limitation, optimal and constant temperatur e).  They are obtained from credible scientific 
sources, but need to be considered as the maximum potential  for the bacterial multiplication, in 
absence of any limiting factor.  In addition the multiplication rates obtained in the laboratory (for 
example on sections of immature fruits) follow re latively massive inoculations with young fresh 
bacterial cultures. 
263. The most likely limiting factor for E. amylovora  in orchard condition is the site where it could 
multiply.  Except in laboratory conditions, no multiplication of  E. amylovora  outside an infection of 
host plant (the first step being on the hypantium) h as ever been described.  So a rapid multiplication is 
possible in an orchard, but only after  infection, in the plant tissues. 
Question 41 
Please comment on whether Roberts and Sawyer ( 2008) is an objective and credible scientific 
analysis containing statistical data appropriately to  measure the risk of importing E. amylovora on 
commercial apple fruit.  Or does the Roberts a nd Sawyer (2008) analysis suffer from the three 
fundamental flaws argued by Australia in paras. 363- 376 of its FWS?  If your response to the latter 
question is yes, do these flaws result in seriously underest imating the fire blight risk associated with 
export apples, as argued by Australia in its respon se to Question 105 by the Panel?  (Paras. 4.26 and 
4.251 of New Zealand's FWS;  paras. 363-376 of Au stralia's FWS;  paras. 17-27 of the United States' 
Third Party submission;  R 64 by New Zealand and R 105 by Australia) 
 Dr Deckers
: 
 264. This publication is clearly written in functi on of the dispute between New Zealand and 
Australia with the aim to correct some of the da ta of the earlier publication of the same author. WT/DS367/11 
Page 52  
 
  265. The orchards that are described in the table 1 in the publication of Roberts and Sawyer 2008 
can not be considered as a representative sample for the New Zealand orchard situation of fire blight.  
It is not clearly described in these orchards what control measures were taken in each orchard.  The 
risk of these orchards is indeed a restricted risk because some fire blight control measures have been 
taken. 
266. A second comment is that part of the bact eria can be present as VBNC (viable but not 
culturable) bacteria.  This can be the case when c opper treatments have been made in the orchards and 
this can be a very important aspect because the VBNC status can be temporary and become viable again. 
267. A third comment is that the bacteria can be presen t at a low level and are difficult to detect at 
these low levels. 
Dr Paulin
: 
 268. The Roberts and Sawyers (2008) paper is an interesting piece of serious reasoning about the 
quantification of the probability of transport of fire bl ight with fruits.  Because I am not a statistician, 
I will not comment of the figures given for probabilities and intervals. 
269. As  usual in this type of work, the key-step of the selection of the input data is very difficult to 
achieve, because it must refer to already publishe d data, which have not been collected for the 
purpose of the present study:  the data set can not comp letely satisfactory.  Therefore a certain level of 
heterogeneity makes the statistical analysis quite di fficult.  In this case, the orchards under analysis 
were very different from each other, (but I do not  understand the point made by Australia that only 
one is from New Zealand?), and the size of the sa mples (n° of fruits assayed) is highly variable (from 
20 to more than 1000).  This makes it difficult to anal yse the data.  In addition, the description of the 
situation of the orchard with respect to fire bli ght is probably too simple, and may reflect, under the 
same qualification, situations of the disease which may be completely different
 in the field. 
270. From these data, the authors did their best to construct a sound reasoning with appropriate 
calculation.  But due to the fact that many assump tions are done, even if I agree that they seem 
perfectly reasonable, I do not think that this paper may help objectively in the dispute.  I am just 
unable, from the reading of this paper to tell if it over- or under-estimates the fire blight risk 
associated with fruits.  I would say that it is an ela borated estimate of what could be the risk, and that 
the figures obtained seem credible, when each st ep is followed, and each assumption accepted. 
Question 42 
Please comment on the conclusions in Australia's IR A regarding the ability of E. amylovora to enter 
into a viable but non-culturable (VBNC) state in mature apples.  Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based on respected and qualified 
scientific sources?  Please comment in this regard the conclusions reached on this matter by Roberts 
and Sawyer (2008).  (Para. 405 of Australia's FWS) 
 
Dr Deckers
: 
 271. The VBNC status of the bacteria is a known status that can be present under orchard 
conditions when Cu treatments are made as a chem ical control method.  This status can indeed 
interfere with the detectible level of EA bacter ia in the epiphytical populations in the orchard.  WT/DS367/11 
 Page 53 
 
 
  Dr Paulin : 
 272. The ability of E. amylovora  to enter into the viable but  non-cultural state is established 
according to the standard in that sort of microbiological studies.  There is no doubt that VBNC state exists for E. amylovora  in the conditions used in the laborator y for this demonstration.  That this 
VBNC state can be obtained with bacterial populati ons (artificially) placed in apple calyx is an 
additional confirmation of this capacity of E. amylovora .  This ability is shared by many other 
bacteria, including Enterobacteriaceae , the taxonomic group in which is placed E. amylovora .  The 
two open questions are:  does VBNC occur in natural conditions from the small population of 
E. amylovora  trapped in apple calyx?  and, to what extent the resuscitation takes place in natural 
conditions, and if so, in which quantity?  The VBNC  state is somewhat a matter of controversy in 
microbiology, and considered by some as just a "pre-death" stage. 
273. Anyhow, even if it must be considered that E. amylovora  does have the ability to enter the 
VBNC state in the calyx of apple, and that resu scitation can occur, in laboratory conditions, the 
conclusions of Robert and Sawyer (2008) for P2 (Probability of survival of the pathogen during 
storage and transport) remain probably valid, due to the speculative incidence of this phenomenon, 
linked to the very low proportion of cells able to  survive as VBNC, and to the complete absence of 
data on the occurrence of VBNC for E. amylovora  in natural conditions. 
Question 43 
Please comment on the probability levels that coul d be reliably derived from the sample sizes 
reported in Hale et al. (1996) and Taylor et al . (2003a).  Were those samp le sizes large enough to 
detect events like the spread of fire blight when appl es contaminated with E. amylovora are placed in 
an orchard?  If not, were the sample sizes in thes e studies nevertheless appropriate?  (IRA, Part B, 
pp. 80-90;  paras. 4.22-4.26 and 4.243 of New Ze aland's FWS;  and paras. 474-475 of Australia's 
FWS) 
 Dr Deckers
: 
 274. It is normal that the size of the samples for such  a detailed study is limited.  But this allows 
interesting conclusions concerning the survival rate  under the different circumstances.  Extrapolation 
of these data to the spread of the disease under diffe rent natural conditions on a larger scale under 
orchard conditions should be considered with prudence. 
Dr Paulin
: 
 275. Combining the sampling dates, the size of the number of fruits analysed reaches 683 fruits in 
Hale et al (1996).  This size is probably not enough to detect a very rare
 event.  Nevertheless it 
provides a valid information on fruit contamination by E. amylovora  under these experimental 
conditions:  such a contamination, whatever th e distance of the fruit sampled from the source of 
bacteria, is not common.  At least it is demonstrated  by these results that the fruits picked from a tree 
showing symptoms are usually  not surface contaminated with the bacteria, in these experimental 
conditions. 
276. The size sample is similar (600) in Taylor et al (2002).  It is again probably not enough to 
demonstrate the occurrence of a very rare event.  Bu t it has to be underlined that each of these apples 
were inoculated with a significant level of bacteria l population.  As such it can be supposed that this 
sample of 600 infested apples, placed in a blooming orchard maximize s the theoretical risk of 
introduction of E. amylovora  with potentially infested apples fruits.  It is probably the maximal size of 
a sample that can be handled properly in an e xperiment.  The study, with these 600 fruits shows 
accurately that the "leak" of bacteria from fr uit to blossoms does not normally take place . WT/DS367/11 
Page 54  
 
  Dr Sgrillo
: 
 277. According the binomial distribution there is a relation (formula 5, appendix 3, ISPM 31)
48 
between the proportion of the population infected and the probability of, at least, one infected unit be 
sampled.  This relationship is illustrated in Figure 1 for a sample size of 1,830 units. 
 
Figure 1.  Relationship between the proportion of the population infected and the 
probability of, at least, one infected unit be sampled (ISPM 3149).  The detail shows 
the upper portion of the curve. 
278. It can be seen, in the detail of Figure 1, that  the higher confidence will only occurs when the 
infection level in the population is above 0.001. 
279. The sample size, reported in the paper, is small to detect very low levels of infection.  Hale et 
al. (1996)50  have used 30 fruits as source of inoculum to infect the orchard.  The expected level of 
infection of the fruits in the orchard, considering a probability of infection of 1E-6 per fruit, would be 
3E-5 (calculated from the Poisson distribution).  To detect this level of infection, with 90% 
confidence level, it would be necessary sample of 76,752 fruits. 
280. The confidence level provided by the sample size used (1,830 fruits) is 5%. 
Question 44 
Please comment on what factors, other than the volume of trade in apples between New Zealand and Chinese Taipei, would need to be taken into acco unt to support a contention that New Zealand's 
experience in exporting apples to Chinese Taipei may be used to draw conclusions on the potential 
for fire blight to enter, establish or spread in Au stralia as a result of imports of New Zealand apples?  
Are the parameters described in th e example mentioned by New Zeal and in its first written submission 
regarding the possibility of transmission of fire blight  through trade in apples in the next shipment 
                                                     
 
48 (footnote original ) Exhibit AUS-30:  International Plant Protection Convention, International 
Standard for Phytosanitary Measures No. 31:  Methodologies for sampling of consignments, 2008, from Report 
of the Third Session of the Commission on Phytosanitary Measures, Rome, 7-11 April 2008. 
49 (footnote original ) Exhibit AUS-30:  International Plant Protection Convention, International 
Standard for Phytosanitary Measures No. 31:  Methodologies for sampling of consignments, 2008, from Report 
of the Third Session of the Commission on Phytosanitary Measures, Rome, 7-11 April 2008. 
50 (footnote original ) Exhibit NZ-27:  Hale CN, Taylor RK and Clark RG (1996) "Ecology and 
epidemiology of fire blight in New Zealand", Acta Horticulturae 411: 79-85.  WT/DS367/11 
 Page 55 
 
 
  from New Zealand or the United States to Chin ese Taipei scientifically reasonable and justified?  
(Paras. 4.183-4.185 of New Zealand's FWS;  para. 310 of Australia's FWS) 
 
Dr Deckers : 
 
281. It is not sure that the Taipei situation and the Australian situation is comparable.  Is the 
climate for both export area comparable?  Climatologi cal parameters such as temperatures T max. and 
T min. and amount of rainfall durin g susceptible period like during the flowering time can be decisive 
for the EA risk.  A second point is the availability of  the host plants;  are they comparable in both 
area? 
Dr Paulin : 
 282. The main differences between Australia and Taipei, apart from volume of trade, and as far as 
introduction of fire blight is concerned, are probably two: 
283. – Even if apples are produced in Taipei, apple orchards are not common
, they are scattered 
onto mountains, for climatic reasons, and not concentr ated in large production zones in the vicinity 
the big towns.  It is very unlikely that packing ho uses for import fruits are placed in the vicinity of 
these orchards. 
284. – Even if Rosaceous plants (crab apples, Stransvaesia ) may be found in Taipei, especially in 
altitude (1500-2000 m), host plants of fire blight ar e not common in town plantations, in streets and 
family or public gardens and parks.  They are quite rare , and  Cotoneaster, Pyracantha  or hawthorns 
are probably almost absent.  They are the most common potential host plants of fire blight in many 
countries, and possibly in certain areas of Austra lia.  Therefore, associated with the paucity of 
orchards, the number of potential host plants in Taipei  for fire blight is far less, and this should be 
taken into account in the analysis. 
285. – In addition, the climate is generally, for most  of the years, in most of the places in the 
island, not favourable to E. amylovora , because too hot (maximal daily temperatures of more than 
30°C are unfavourable to the disease). 
Question 45 
Please comment on the relevance, if any, of any ab sence of historical proof of a pathway for 
excluding or assessing a certain risk.  Please take into account any IPPC standards on the matter.  
(R 65 by the Parties) 
 
Dr Deckers : 
 286. Historical data can indicate indeed that a certain pathway of disease introduction is very 
unlikely and can give interesting indications on the real risk assessment. 
Dr Paulin
: 
 287. Generally speaking, absence of historical proof can be relevant to the estimation of a risk.  
Although it provides just an assumption of futu re absence, it can be enough in certain cases. 
288. For fire blight, it is more difficult
 to rely on such an absence of historical evidence, for two 
reasons: 
289. – Epidemies of fire blight are impossible to trace , conversely to epidemy of some human viral 
or bacterial diseases, b ecause the pathogen ( E. amylovora ) shows a low level of variability.  Even if WT/DS367/11 
Page 56  
 
  some differences between strains have been observe d, they are not enough to characterize a strain 
found in a new place and to link accurately the new outbreak to one particular source of inoculum.  
Some attempts have been presented in the literature (Jock et al. 2002) but they remain very limited, 
and not completely convincing. 
290. – Conversely to human diseases, plant diseases, even  when carefully surveyed in some places 
like fire blight are not officially assessed with a rigor
 and a frequency which would provide definite 
clues for the introduction of the disease in a new site. (See question 16). 
291. Actually in the general situation for fire blight , the origin of inoculum is just a matter of 
assumption s and suppositions.  Nothing is really proven, except in some cases, notably when the 
recent  introduction of contaminated host plants is  involved.  But very often these plants are illegal 
imports, and not traceable. 
292. Against this background, the absence of historical proof is not  per se  a sufficient reason to 
exclude a possibility.  Given the importance of inte rnational trade of apples, between contaminated 
and non-contaminated countries in the world, the total absence of historical proof (or even suspicion) 
shows at least that fruits do not constitute a comm on pathway for introduction of fire bight in a new 
area. 
Dr Schrader : 
 293. The absence of historical proof of a pathway would not be a scientifically sound reason for 
excluding a certain risk regarding the entry of a p est, as conditions and situations may change, e.g., 
the concentration of the pest in the area of origin, th e application of treatments in an infested area, the 
frequency and volume of pathways, etc. 
Question 46 
Does Australia's IRA provide an objective and coheren t assessment of the likelihood and implications 
of New Zealand apples being repacked at rural packi ng houses in close proximity to orchards, when 
assessing the risks related to fire blight, European  canker and ALCM?  Was such assessment made 
with proper methodological rigour?  (Para. 4.418 of New Zealand's FWS;  R 99 by Australia) 
 
Dr Deckers
: 
 294. This assessment is not convincing and seems  not to be based on objective criteria. 
Dr Paulin
: 
 
295. The assessment made by IRA is apparently coherent, but I do not see how are evaluated the 
relative levels of probability for each situation.  Besides, I do not see the point, if apples from New 
Zealand are imported as ready to sold.  This  question seems to me of minor importance  for fire blight 
risks.  I think that the time of import (whether  it takes place during a period of receptivity of host 
plants or not) is more important in the risk assess ment than the site of import and (hypothetical) 
packaging.  WT/DS367/11 
 Page 57 
 
 
  Dr Sgrillo : 
 296. The Australia's IRA considers two extremes scenarios:  a) from 70% to 100% of apples being 
repacked at rural packing houses and b) from 0.1% to  5% of apples being repacked at rural packing 
houses.
51 
297. As Australia states that "the probability va lues derived from the two different P1 values 
barely differ at all"52 there are no implications whether the imported apples will be repacked or not. 
Question 47 
Is the requirement identified in Australia's IRA that a packing house provide details of the layout of 
the premises, sufficiently justified by the scientific evidence relied upon?  (IRA,  Part B, pp. 317;  
para. 4.149 of, and pp. 242 and 247 of Annex 4 to, Ne w Zealand's FWS;  and para. 963 of Australia's 
FWS) 
 
Dr Deckers : 
 
298. I don't see the scientific evidence for that measure. 
Dr Paulin : 
 299. Very few scientific data, if any, support the risks of contamination of fruits by  
Erwinia amylovora  in the packing houses.  It seems that the requirements of providing details of the 
layout of the premises is not based
 on any "scientific evidence". 
Question 48 
Please comment on whether, from a technical persp ective and as described in Australia's IRA, the 17 
specific measures that have been challenged by New Zealand can be distinguished  as either measures 
active in risk reduction, or measures designed to im plement or support active measures.  (R 14-26 by 
the Parties) 
 
Dr Deckers : 
 300. I think that all the measures d escribed in Australia's IRA can be considered as measures that 
reduce the risk for infections actively directly or  indirectly.  Some of the measures describe the 
implementation of the measures, but in fact the result for all these measures is always with the 
intention to reduce the infection risks. 
Dr Paulin
: 
 301. I would consider that measures that are active in risk reduction are measures that directly 
result in decreasing the chance of fruits to carry
 E. amylovora .  In this category I would place: 
– Apples sourced from areas free from disease symptoms, 
– Orchard be suspended in case of pruning suspected to be devoted to cancel 
symptoms, 
– Orchards be suspended in case of fire blight symptoms, 
                                                      
51 (footnote original ) IRA Table 21 p. 97. 
52 (footnote original ) R 99 by Australia. WT/DS367/11 
Page 58  
 
  – Apples be subjected to disinfection, 
– Grading and packing equipment be cleaned and disinfected. 
302. These measures could be supposed to be supported by the followings: 
– Orchards are inspected for fire blight disease symptoms, in order to minimize 
the available inoculum at the time of picking the fruits, 
– An orchard methodology inspection be developed..., in order to guarantee a 
level of safety and objectivity to the inspection, 
– Packing houses be registered for export process only fruits sourced from 
registered orchard, in order to minimize the risk of pollution of apples to be exported 
by bacteria possibly contaminating apples for local market, 
– AQIS be involved in inspection for fire blight, 
– AQIS be involved in verification of packing houses, – New Zealand guarantees that export orchard are registered, – Lay out of the premises of packinghouses is made available. 
Dr Schrader
: 
 
303. Principally and without going into detail for each of the 17 measures, a distinction between 
measures active in risk reduction and measures for implementing active measures can be made.  E.g. 
measure No. 3 (The requirement that an orchar d/block inspection methodol ogy be developed and 
approved that addresses issues such as visibility of sy mptoms in the tops of trees, the inspection time 
needed and the number of trees to be inspected to meet the efficacy level, and training and 
certification of inspectors) can be seen as an implementing measure to measure No. 1 (The 
requirement that apples be sourced from areas free from fire blight disease symptoms).  See also comments on systems approaches below (answer to question 140). 
III. EUROPEAN CANKER 
Question 49 
Please comment on whether an apple fruit that is naturally (rather than experimentally) 
endophytically infected or epiphytically infested with European canker can still develop into a 
healthy-looking mature fruit.  Based on Australia 's IRA, please comment also whether any of the 
challenged requirements imposed by Australia wi th respect to European canker are based on a 
finding that such situation is possible.  If so: a. What is the scientific basis contai ned in the IRA for such a finding? 
b. Is the finding in the IRA in this regar d based on respected and qualified scientific sources? 
c. Is the reasoning articulated by the IRA on the basis of such scientific evidence, including the 
methodologies applied, objective and coherent? d. Do the results of the IRA's assessment in this regard suffic iently warrant the challenged 
requirements related to European canker?  WT/DS367/11 
 Page 59 
 
 
   
Dr Deckers : 
 304. It is possible that apple fruit is infected natura lly endophytically with NG and still develops to 
a normal looking fruit at the end of the season and th at the NG infection shows up only after a storage 
period of some months. 
305. The epiphytical infection of NG will not be so  frequent in comparison with the endophytical 
infection. 
Dr Latorre
: 
 
306. Australia's IRA was based mainly on the possi bility that mature apples may carry latent 
infections, which cannot be detected at harvesting or during processing in the packing house.  Latent 
infections may occur in a small proportion of th e fruits harvested from cankered trees if frequent 
summer rainfalls occurred at harvest.  Fruit infectio ns are negligible or extremely low in areas with 
dry climate conditions at harvest.  If cankered trees are not prevalent (0% infected trees), I would not 
expect to observe any latent infections, even unde r high summer rainfalls.  Therefore, the risk of 
entrance would vary considerably based on clim ate conditions and disease prevalence and severity. 
307. Endophytic N. Galligena  has been suggested to occur on young apple trees, which may be 
important because it could explain the developmen t of European canker in young apple orchards, 
particularly in areas where other sources of primary inocula are nonexistent (Langrell, 2002, Mycol. Res. 106:280-292; McCracken et al., 2003).  However, to my knowledge, there is no information 
demonstrating that N. Galligena  can be found endophytically on mature apple fruits.  Therefore, an 
endophytically infected fruit is a possibility rather than  a real issue, which needs to be proven before 
admitting this as an important mechanism for long-distance dissemination of N. Galligena . 
308. There is no information demonstrating that conidia or ascospores of N. Galligena  can survive 
epiphytically (as surface contaminant) on mature apple fruits.  It is important to consider that conidia 
survive desiccation for relatively short periods an d it would be very unlikely that conidia and 
ascospores, contaminating apple surfaces, can survive post-harvest fruit management. 
309. To my understanding, the challenged requirement s imposed by Australia were based mainly 
on the possible occurrence of latent fruit infection,  but not on endophytic infections.  The possibility 
that clean fruits may be infected from inocula co ntaminating epiphytically mature fruits in dump 
water in packing houses (Importation step 5) is ne gligible and irrelevant.  Arguments supporting this 
conclusion have been provided by Australia (AUS-BA Part B, p. 127).  Nevertheless, this possibility 
was analyzed by Australia's IRA, which ac knowledged that a small number of spores could 
contaminate fruits in the packing process.  Ho wever, there is no experimental information 
convincingly supporting this conclusion.   Therefore, this was a rather arbitrary decision that should be 
reviewed. 
Dr Swinburne
: 
 310. Epiphytes are organisms that can not merely survive, but can actually grow (at least to some 
extent) on the intact surface of plants drawing on nutrients leached through the cuticle.  There is no 
evidence that N. Galligena  can survive as an epiphyte per se.  However, it is possible that the surface 
of an apple fruit could become contaminated by  spores washed down from active canker lesions by 
rain.  During the summer season these would be c onidia.  The data obtained by Dubin & English 
(1974) implies that conidia on the fruit surface would only survive for a few days if humidity was maintained at 100%.  At lower humidity (85%) the ha lf-life of conidia would be a matter of hours.  
Unlike some other species responsible for apple rots e.g. Phomopsis mali , (Ayob & Swinburne, 1970), WT/DS367/11 
Page 60  
 
  conidia of N.galligena  are not able to initiate infection throu gh the intact cuticle of fruit, consequently 
conidia adhering to the unbroken surface are unlikely to survive for long periods or contribute to fruit 
rots. 
311. Endophytes are organisms which can grow within the tissues (intra-cellular or in the 
transpiration stream within the xylem) without pr ovoking overt symptoms.  There is some evidence 
(Dewey, Li & Swinburne, 1995) that N. Galligena  can survive and be transported within the xylem 
into regions of the wood that are remote from canker lesions.  Whilst this may be superficially 
symptomless, internal staining of affected areas implies that cellular damage is taking place, thus N. Galligena  can not be classed as an endophyte. 
312. A central contention of the IRA is that fruit at th e time of harvest can be infected but show no 
symptoms of rotting.  Apple fruit of all cultivars (see Q55) can express resistance to rotting by 
N. Galligena  during their early developmental stages, up to and usually including harvestable 
maturity.  Where wood canker lesions are prevalen t, and the weather conditions are conducive to 
conidia production throughout fruit development, it is inevitable that infection (in the strict sense) of 
fruit can take place at any time.  These infections will  involve some colonisation of cells in lenticels, 
around growth cracks in the well at the stem end, or  within the open area at the calyx.  Cells in the 
immediate neighbourhood will respond by producing be nzoic acid, which is fungitoxic.  Further 
growth of the fungus may be prevented permanently or  temporarily.  If the latter, then the term most 
applicable is that a quiescent infection has occurre d.  As apples ripen two major changes, reduction in 
the acidity and increase in soluble sugars, reduce th e toxicity of benzoic acid, enabling the fungus to 
resume growth and progressively rot the fruit.  For most cultivars in current commercial production 
this will occur after harvest.  Consequently it is possible for infected fruit of all varieties to be 
harvested with no visible symptoms (see Q55). 
313. The IRA makes the statement that dessert apple varieties rot with N. Galligena  before harvest 
quoting Swinburne, 1975.  This actually refers to  the observations made by Dillon-Western (1927), 
with the cultivar Worcester.  This cv. ripens excep tionally early, often before harvest and which can 
not be held in store for long periods; all reasons why it has lost favour in commerce.  It is untypical of 
modern dessert cultivars, in which most rots are seen post-harvest. 
314. The sequence of events outlined  above are applicable to regions where wood cankers are 
frequent and weather conditions favour production of conidia duri ng the summer months (e.g. the 
U.K., and N. Ireland in particular).  The presence of  stem lesions alone can not predict the likelihood 
of fruit infection.  It is unfortunate that there is so little data on the causes and extent of rotting of fruit 
in New Zealand, but what there is suggests that  summer weather conditions are not favourable for 
infections by N. galligena and the challenged requirements seem excessive (see Q72). 
Question 50 
According to respected and qualified scientific s ources, can export-quality mature apple fruit carry 
the causal organism of European canker (either inte rnally or externally)?  Please comment on the 
timeframe for an infected mature apple fruit (taking into account varietal differences) to develop 
visible symptoms of European canker.  Did Australia 's IRA take into account relevant evidence in this 
respect regarding fruit harvested from an orchard? 
 
Dr Deckers
: 
 
315. Export quality apple fruit can carry the NG funga l infection internally on susceptible apple 
varieties.  The chance for externa lly presence of the disease on the fruit sk in is not expected to be high 
because the fungicide treatments made at the end of the growing season against storage diseases can 
have an effect on the NG that should be present externally on the fruit skin.  WT/DS367/11 
 Page 61 
 
 
  Dr Latorre : 
 316. On the basis of the information discussed in AUS-2 BA, Australia's IRA considered 
biological and epidemiological evidence currently  available with respect to European canker. 
317. To my knowledge, the external contamination (epiphytically) of apple fruits with 
N. Galligena  has not been documented scientifically;  it is  very possible that external contamination 
does not occur or has no epidemiological consequences.   Therefore, the probability that mature fruits 
carry N. Galligena  externally should be equal to zero, and disregarded in the risk analysis. 
318. However, it is feasible that N. Galligena  can develop as a latent infection at harvest and 
hence, apparently healthy (asymptomatic ) mature apples eventually could carry N. Galligena  
internally.  Infected but asymptomatic fruits would be  impossible to differentiate from healthy fruits at 
harvest or during post-harvest processing. 
319. The timeframe for an infected mature apple fruit to develop visible symptoms varies from a 
few (6 to 7) days to several weeks or months (2  to 3 months), primarily depending on apple variety 
and on ambient temperatures.  Highly susceptible vari eties become rotted and drop off in the orchard 
before harvesting.  This considerab ly reduces the risk of entrance of N. Galligena  on mature apples. 
Dr Swinburne
: 
 320. As outlined above (Q49) apples can have quiescent infections at harvest.  The time-frame for 
the subsequent development of overt rots rests on a number of variables which have not been explored 
experimentally in detail.  These include the cultivar , the time of infection and the conditions imposed 
during the storage period.  Low temperature coupled  with controlled atmospheres can and will delay 
rot development in any cultivar.  The conditions with in the store play a majo r role in the speed of 
development of rots (Berrie, Xu &Johnson 2007, a nd appendix 1).  Obviously the longer fruit remain 
in store the more rots develop. 
Question 51 
Based on Australia's IRA, do the challenged requirements imposed by Australia with respect to 
European canker provide for any tolerance of th e presence of N. Galligena?   Please comment on 
whether the following terms exp ress different concepts: "area freedom", "pest free places of 
production", "freedom of the disease" and "freedom of the visible symptoms of the disease".  How relevant is a distinction between these concepts in  the context of Australia's measures for European 
canker?  In light of Australia's IRA and Australia 's R36 to the Panel, how do these various terms 
relate to relevant ISPMs, in particular ISPMs Nos. 4, 5, 10 and 22?  (Paras. 4.443 and 4.447 of 
New Zealand's FWS;  paras. 156-160 of Aust ralia's FWS;  R 33-35 by New Zealand) 
 
Dr Deckers
: 
 
321. Depending on the different weather conditions , th ere will be different situations concerning 
the NG presence and development in orchards.  For NG freedom of visible symptoms of NG does not 
mean that there can not be a hidden presence of the disease with a delayed symptom expression e.g.on fruits with an internal infection of NG.  Also  infections of NG on young fruit trees coming from 
infected fruit tree nurseries can be present for so me months before the symptom expression becomes 
visible on the trees. 
Dr Latorre
: 
 322. In the challenged requirements with regard to N. Galligena,  a disease tolerance level was 
provided by Australia for fruits imported from New Z ealand; this disease tolerance level was implicit WT/DS367/11 
Page 62  
 
  in the import risk analysis (IRA) (AUS-2 BA, p. 152 and p. 113).  Austra lia's IRA recognized disease 
tolerance while establishing an appropriate level of protection (ALOP) in their pest risk analysis 
(PRA) approach, which was part of the overall IRA.   According to Australia, the ALOP reflects the 
maximal acceptable risk (or expected loss) from a di sease incursion in Australia.  On the basis of this 
analysis, a LOW annual probability of entry, est ablishment and spread (PPEES) was assumed for 
fruits imported from New Zealand, and MODERATE consequences were established if European 
canker eventually established and spread in Australi a.  The interaction of these two factors allowed 
Australia to conclude that a LOW unrestricted annual risk exists.  Therefore, management measures to 
mitigate this risk were proposed. 
323. The PRA, and particularly the ALOP, is the cr ucial aspect of this dispute with regard to 
European canker.  Australia considers PPEES low.  However, there is a general perception that 
PPEES is extremely low or negligible in other appl e-producing countries.  Data provided by Australia 
to support their conclusion appear to be insufficient.   For instance, data to validate the probability of 
N. Galligena  entrance via asymptomatic fruits has not been provided;  similarly, data supporting the 
probability of establishment and spread were not presented. 
324. The long experience of other exporting countries where European canker is present (e.g., 
Chile, United States) suggests that the probability th at asymptomatic fruits carrying latent infection 
may introduce N. Galligena  into a new area is negligible (extre mely rare), rather than low.  This 
probability would increase if apples were harvested fr om infected orchards lo cated in areas with high 
summer rainfalls.  Therefore, the risk of long-di stance disease spread by inf ected fruits (fruits with 
latent infection or visible symptoms of the disease) should be considered extr emely low or negligible 
until sufficient experimental evidence is provided to neglect this conclusion. 
325. "Area freedom" was used to denote "pest-free area" , and "freedom of the disease" was used to 
denote "pest freedom," as explained below.  "Freedom from visible symptoms of the disease" is a pathological expression meaning asymptomatic (= symptomless) or apparently healthy.  
Asymptomatic fruits may or may not have latent infections. 
326. The following terms have been defined previ ously by FAO (International Standards for 
Phytosanitary Measures, ISPM); they are defined and used primarily in the In ternational Standards for 
Phytosanitary Measures (ISPM) Nºs 4, 5 and 10 and, to my understanding, they are correctly applied 
by Australia's IRA.  ISPM 22 refers to a related s ubject, "Requirements for the Establishment of Areas 
of Low Pest Prevalence": 
327. Pest-free area , an area where it has been scientifically  demonstrated that a specific pest (pest 
or disease) does not occur and in which, where a ppropriate, this condition is being officially 
maintained.  The objectives of the pest-free area a nd the pest-free place of production are similar, but 
are implemented differently.  A pest -free area is much larger than  a place of production.  It may 
include several places of production and it may extend to a whole country or parts of several countries.  A pest-free area may be isolated by a na tural barrier or buffer zones.  A pest-free area is 
officially maintained by the National Plant Prot ection Organization (NPPO) of the exporting country 
over many years without interruption.  This concept is defined in ISPM 5 and the requirements for the 
establishment of a pest-free area are discussed in ISPM 4. 
328. Pest-free place of production, a production place  in which a specific pest  
(pest or disease) 
does not occur, as demonstrated by scientific eviden ce and in which, where appropriate, this condition 
is being officially maintained for a defined peri od (ISPM 10).  A pest-free place of production may be 
situated within an area where the p est concerned is prevalent;  it is isolated by buffer zones in its 
immediate vicinity.  It may be maintained for only one or a few growing seasons, and it is managed 
individually by the producer, under the supe rvision and responsibility of the NPPO.  WT/DS367/11 
 Page 63 
 
 
  329. "It provides a means for an exporting country, if so required by an importing country, to 
ensure that consignments of plants, plant products  or other regulated articles produced on, and/or 
moved from, the place of production are free from the pest concerned, because it has been shown to 
be absent from that place over a relevant period of time." 
330. Pest-free production site, a defined portion of a place of production  in which a specific pest 
(pest or disease) does not occur, as demonstrated by scientific evidence, and in which, where 
appropriate, this condition is be ing officially maintained for a defined period.  The pest-free 
production site is managed as a separate unit in the same way as a pest-free place of production  
(ISPM 5 and 10). 
331. Pest freedom  is a condition established by surveys and/ or inspections to prevent the entry of 
the pest (pest or disease) into the place of productio n.  The operations are supported by appropriate 
documentation.  The concept of "pest freedom" a llows exporting countries to provide assurance to 
importing countries that plants, plant products and othe r regulated articles are free from a specific pest 
or pests and meet the phytosanitary requirements of the importing country when imported from a pest-free place of production (ISPM 10 and 22).  The establishment of areas of low pest prevalence 
(ALPP) has been addressed by Australia's IRA as anot her strategy to minimize the risk of entrance of 
N. Galligena  on apple fruits from New Zealand (AUS-2 BA, p. 152). 
Dr Swinburne
: 
 332. The concepts encompassed by the various phrases used in the documentation to describe 
pest/pathogen status of production areas are confusing,  and need to be "unpacked".  There are three 
possible conditions:  1) the pest/pathogen is absen t, therefore no disease, 2) the pest/pathogen is 
present, but for some reason the disease is not visibl e, 3) the pest/pathogen is present and the disease 
is visible. 
333. In contrast to the fire blight pathogen there are no tests for the presence of N. Galligena  in 
trees that would make it possible to assess an orchar d for the presence of the fungus in the absence of 
visible symptoms.  Consequently the IRA depends upon the inspection of orchards for these 
symptoms.  However, the IRA does not seemingly define or is ambiguous concerning the unit of 
production which must be disease free.  This could be the block, orchard, farm or geographical region.  
It also has no tolerance limits for areas with low levels of infection. 
Question 52 
In your view, is the proportion of retail-ready, co mpared with bulk, apple imports from New Zealand 
relevant for the assessment of risks in relation to Eur opean canker?  If yes, how?  (IRA, Part B, p. 9;  
Paras. 4.74 of New Zealand's FWS;  R 8-10 by the Parties) 
 
Dr Deckers
: 
 
334. I think there is no substantial difference between  retail ready apples compared with bulk apple 
preparation in relation to European canker.  The moment of preparation of the fruits will determine 
whether hidden infections will come out later or not. 
Dr Latorre : 
 335. As "retail-ready" apples are more commonly imported than bulk apples, one would expect to 
lower the chances of symptom development because "retail-ready" apples are commercialized and 
usually consumed more rapidly than bulk apples.  Additionally, it is possible that bulk apples would 
be packed near apple orchards, increasing the probab ility of spread and establishment in the case that 
infected and sporulating fruits were discharged near apple trees. WT/DS367/11 
Page 64  
 
  Dr Swinburne
: 
 336. The location of the final grading operation could have an impact on the probability of fruit 
rotted by N. Galligena  entering Australia from New Zealand, linked with the time elapsed since 
harvest (see Q50).  Symptomless fruit harvested, held  in New Zealand in bulk bins and then shipped 
to Australia could have time deve lop rots, which would then be graded out only after arrival.  By 
contrast, fruit graded into retail ready packs in Ne w Zealand would remove any rots and would greatly 
reduce the time available for further rots to develop before consumption (see Q91). 
Question 53 
Based on Australia's IRA, what is your understanding as to what might be the "appropriate cultural 
practices and fungicide sprays used to minimise the likelihood of [European] canker infections"?  
In practice, could this encompass no treatment at all where nursery stock has been sourced from 
areas verified as free from European canker? 
 
Dr Deckers
: 
 
337. There are important periods for fungicide appli cations with the aim to reduce NG infections:  
such a period is the leaf fall period at the end of the season because the leaf scars form a preferred infection pathway for a NG infection.  When a NG infection occurs on the branches via leaf scar, it is 
important to prune the infection out and to rem ove it from the orchard and burn the infection.  A 
second important period for fruit infection by NG is  the blossom period during which an internal 
infection in the core of the fruit can develop.  Al so here the application of specific fungicides can 
reduce the infection level substantially. 
338. Exclude the treatments completely when the nursery stock has been sourced from areas 
verified free from European canker can be risky. 
Dr Latorre
: 
 
339. Cultural practices (sanitation) should include (i ) canker removal (cankered stems) and (ii) 
removal of rotting fruits from trees and orchard floor s.  These cultural practices should be integrated 
with chemical control using specific fungicides,  preventively sprayed (pre-infection) in late 
November or early December to reduce i noculum production and fruit infection. 
340. The program would involve no treatment where summer rainfalls are non-existent and where 
disease trees (cankered trees) have not been detected.  However, treatments should be considered in 
areas highly prone to disease development. 
Dr Swinburne : 
 341. Appropriate cultural methods specifically for the control of European canker are obviously 
required only where the pathogen is present.  These would include the rigorous removal of infected 
branches or trees, and the application of fungicides at vulnerable periods such as leaf fall or bud burst.  However the application of protectant and/or erad icant fungicides for the control of other diseases, 
notably apple scab ( Venturia inaequalis ) have a profound impact on the severity and spread of canker 
(Swinburne, 1975) as has been confirmed by Cooke (1999) and Lolas & Latorre (1996).  It is reassuring to see that newer scab fungicides replaci ng those that have been withdrawn also control 
canker. 
342. As the "Millennium Trial" (McCracken et al, 2003) indicated, sourcing trees for new orchards 
from disease-free nurseries is an important first step  in the prevention of European canker.  There 
have been a number of instances in the UK where ea rly problems with this disease in new orchards  WT/DS367/11 
 Page 65 
 
 
  were probably attributable to the use of ma iden trees that carried the disease from the nursery 
(personal observations). 
Question 54 
Please comment on whether Australia's IRA a ssessment regarding the transmission of European 
canker depends on mature apple fruit being either late ntly infected or infested with the causal 
organism of European canker.  Please comment on whether Braithwaite (1996) is reliable and 
relevant in this context.  (Paras. 4.63 and 4.273 of  New Zealand's FWS;  para. 545 of Australia's 
FWS;  and  R 70-71 by the Parties) 
 
Dr Deckers : 
 
343. The transmission of European canker can be made  aswell by fruits latently infected as by 
fruits infested via the lenticels with spores of NG.  The rotten fruits can bring the NG into an orchard 
and spread the disease.  The experience of Braithwaite is considered to be rele vant in this context. 
Dr Latorre : 
 
344. Australia's IRA assessment was based mainly on the possibility that mature fruits can be 
infected before harvest without developing symp toms at harvesting or during processing in the 
packing house (latently infected fruits).  Sympto ms will develop after weeks or months of cold 
storage.  Braithwaite (1996) (Exhibit NZ-34) publ ished a brief review on the currently available 
knowledge regarding European canker, based on studies of the disease's development in the 
United Kingdom and Northern Europe, without ex amining conditions in New Zealand.  No new 
objective data is reported in this paper.  Therefor e, I agree that it is not a reliable and relevant 
reference to support the hypothesis that latent in fections may also occur in mature apple in 
New Zealand. 
Question 55 
Based on the relevant parts of Australia's IRA, please comment on whether the IRA addressed the risk 
associated with latent infection with the causal  organism for European canker in regard to dessert 
apples with the necessary scientific and methodolog ical rigour.  (Paras. 4.62 and 4.284 of 
New Zealand's FWS;  R 72 by Australia) 
 
Dr Deckers : 
 
345. In Belgium we have the experience that d essert apples like Jonagold or Gloster can be 
internally latenly infected by NG and these infections  can develop later during storage to fungal rot on 
the apples. 
Dr Latorre : 
 
346. It is true that Australia's IRA based their ri sk assessment on the information already published 
from studies in Northern Ireland (Swinburne, 1964, 1975, Exhibits NZ-11 and NZ-9, respectively).  These results were obtained on apple varieties quite different from those produced today in 
New Zealand and under environmental conditions that  appear to be far more conducive to fruit 
infection (in Northern Ireland) than those in New Ze aland.  Although this does not invalidate the risk 
assessment analysis, and it does not reject the hypoth esis that latent infections may occur in mature 
fruits in New Zealand, it is a factor that should be ta ken into consideration by Australia's IRA.  Latent 
infection on mature fruits should not be under discu ssion, but the probability of latent infection in 
many apple cultivars produced under different envir onmental conditions in New Zealand is of utmost 
interest. WT/DS367/11 
Page 66  
 
  Dr Swinburne (Response to questions 54 and 55)
: 
 347. There are no reports which imply that rotted appl es are in any way involved in the transfer of 
infection with N. Galligena to "clean" orchards. 
348. In Europe dessert cultivars of apples fre quently develop post harvest rots by N. Galligena  and 
the phenomenon of quiescent (latent) infection is by no means confined to the cooking variety 
Bramley's Seedling as the NZ FWS states (Berrie, 1989 and appendix 2). 
349. Braithwaite (1996) contains an unconfirmed re port that fruit rotting with this pathogen has 
been detected in NZ, and it see ms to be accepted by both parties that this does occur occasionally, 
although it is by no means clear if these reports refe r to pre- or postharvest.  Braithwaite then goes on 
to speculate that rotted fruit can transmit infecti on, basing his argument on European observations on 
the formation of ascospores on mummified fruit.  This is a very rare occurrence, and most unlikely to 
be found in the climates of NZ or Australia (see  Q56 7 Q66). For  these reasons this aspect of the 
paper can be disregarded. 
Question 56 
When considering the relevant factors for the likelihood of establishment and spread of European 
canker, taking into account respected and qua lified scientific sources, please comment on the 
relevance of both temperature and rainfall frequency.  In order to accurately assess the likelihood of 
establishment of European canker, what relevance would the annual average amount of rainfall have 
by itself?  (IRA, Part B, pp. 137, 140 and 146;  paras. 4.87-4.91 and 4.315 of New Zealand's FWS;  Para. 84 of Australia's FWS) 
 
Dr Deckers
: 
 350. The average amount of rainfall on itself is not th e most important factor;  also the time of 
rainfall during a susceptible period like the leaf fall period or during the blossom time is more 
important. 
Dr Latorre
: 
 351. As stated by Third Parties, three key factors are necessary for the infection of apple fruit with 
European canker:  (i) conducive climatic conditions ;  (ii) the presence of a susceptible host;  and (iii) 
sufficient inoculum concentration.  The co-occurre nce of these three factors is necessary for fruit 
infection.  It has been demonstrated that humid (wet) conditions are necessary for inoculum 
production and liberation.  Frequent rains are essen tial for conidia and ascospore dissemination from 
cankered lesions to fruits within infected trees.  Therefore, mature fruits would only carry latent 
infection in cool and rainy summer climates.  The likelihood of establishment and spread of European 
canker after entrance in a new area would be highly  dependent on the occurrence of these factors as 
well. 
352. Annual rainfall provides a general indication of  areas with climates conducive to European 
canker.  It has been postulated that annual rain falls higher than 1000 mm are indicative of climate 
conditions highly conducive to the development of  European canker.  However, European canker 
occurs in areas with less annual rainfall.  Rain fall is important for infection during two critical 
periods:  (i) during leaf fall, because infection may o ccur through leaf scars, resulting in twig and stem 
cankers that appear during the next growing season,  and (ii) during harvest, because rainfall favours 
fruit infection and eventually latent infection in ma ture fruits.  Knowledge of the rainfall distribution, 
during the growing season, is important for unde rstanding the epidemiology European canker on 
apples.  WT/DS367/11 
 Page 67 
 
 
  Dr Swinburne : 
 353. Rainfall impacts at every stage of the infection cycle of N. Galligena, beginning with the 
production of spores from existing lesions.  This is pa rticularly evident in regions that have distinct 
"rainy seasons".  For example, on the western sea- board of the U.S.A. Zeller (1921) noted that 
perithecia did not appear in Oregon until some months  into the wet rainy winters, and Wilson (1966) 
made similar observations for conidia in California.  However, it is not the absolute volume of rain 
that correlates with the numbers of spores released  (both ascospores and conidia) but the duration of 
"leaf wetness", (i.e. the presence of free water on the plant surface) (Swinburne, 1971).  Thus a short 
storm in which several centimetres of rain falls in an hour would be much less conducive to spore 
release than when the same volume falls over a peri od measured in days.  Likewise, even after the 
arrival of viable spores in the infection court (e.g . leaf scars) a continuing period of leaf wetness is 
required for successful infection. Dubin & Eng lish (1974) working in California found that no 
infections developed unless leaf-w etness was maintained for at least  6 hours.  More recently Latorre 
et al  (2002) in Chile found that this could be as little as 2 hours at the optimum temperature, and 
demonstrated the interaction between temperature and wetness.  The number of days with rain will 
give a much more accurate indicator of the likelihoo d of infection, especially when examined in terms 
of the seasonal frequency of rain days. 
354. There is no information on the effect of temper ature on spore formation or discharge, only for 
infection.  Latorre et al (2002) demonstrated an interaction be tween temperature and the hours of leaf 
wetness required for the successful infection of leaf  scars following artificial inoculation, which forms 
the basis for predictive model used  in Chile.  The hours required decreased linearly with increases in 
temperature between 10 and 20 C, and at 20 C only 2 hours was needed, the shortest time so far 
recorded.  It has to be noted that a predictive mode l for leaf-scar infection such as that from Chile is 
based on the presumption (probably valid there) that conidia would be available at all times.  In 
regions of intermittent rainfall this would be inco rrect (Wilson 1966), and therefore using for example 
the number of rain days with suitable temperatures for leaf-scar infection without allowing for spore 
production could overestimate the likelihood of infection. 
355. For all these reasons mean a nnual rainfall/temperature data alone will be misleading in 
predicting the possibility that N. Galligena  could become established in any new region. 
Question 57 
On the basis of scientific eviden ce, is the reasoning articulated in Australia's IRA objective and 
coherent in relation to the following points:  (i ) whether N. Galligena may cause fruit rots in 
New Zealand dessert apple fruit;  (ii) whether la tent infections may occur on mature New Zealand 
apple fruit;  and (iii) the likelihood of a pathway via surface-contaminated mature New Zealand apple 
fruit?  Is this evaluation contained in Austra lia's IRA regarding these points objective and credible on 
the basis of the available scientific evidence? Is  it based on respected and qualified scientific sources?  
(Paras. 4.57-4.68 and 4.266-4.300 of New Zealand's FWS;  para. 604 of Australia's FWS;  and R 74 
by New Zealand) 
 
Dr Deckers
: 
 356. I don't know the situation of the NG infections in fruit rot in New Zealand but under European 
situation this would be possible for the three cases mentioned. 
Dr Latorre
: 
 357. On the basis of scientific evidence, N. Galligena  may potentially cause fruit rots in 
New Zealand dessert apple fruits in areas or years with frequent summer rainfalls at harvest.  The 
prevalence and severity of fruit infection can vary  considerably, according to weather conditions.  WT/DS367/11 
Page 68  
 
  Frequent summer rainfalls are necessary for inoc ulum production, dissemina tion and infection.  If 
summer rainfalls are frequent, it would be reasonable to assume that some of the infected fruits may develop symptoms on the tree, and other fruits may be  latently infected, developing symptoms after 
several weeks or even months in cold storage. 
358. After reviewing Figure 1 (Paras. 4.58 NZ FWS), which explains the probability that summer 
conditions are conducive for European canker at sites in the United Kingdom (Loughgall, 
East Malling), United States (Sonoma), New Zealan d and Chile (Talca), it appears that summer 
conditions in New Zealand are very unfavourable fo r the development of European canker, and that 
fruit infection would be an extremely rare event.  Therefore, the likelihood of latent infection on 
mature apple fruits would be extremely low or negligible. 
359. The likelihood of a pathway via surface-contam inated mature New Zealand apple fruit is 
unknown.  Based on the scientific information acquired thus far, surface contamination (ascospores 
and conidia epiphytically contaminating fruit surfaces)  appears to be non-existent.  This possibility 
should be disregarded from the risk analysis. 
Dr Swinburne
: 
 
360. Fruit of the cultivars of apple comparable to those grown in  New Zealand can and do become 
infected in the UK during the growing season with  N. Galligena , and these infections generally 
remain quiescent until after harvest, becoming visible progressive rots only after a period in store.  This is the general experience in many fruit growin g regions in Europe.  Where this is common the 
distribution of rainfall in the summer months allo ws (a) the production of spores (conidia) on active 
stem cankers, (b) the dissemination of those spor es in run-off from cankers onto the developing fruit 
and (c) a sufficient period of leaf-wetness to a llow the deposited spore to germinate and colonise 
limited areas within the calyx or lenticels.  (See Q56) 
361. The limited information available in both FWS documents suggests that rots attributable to 
N. Galligena  in fruit grown in New Zealand are by no means as common as they are in Europe, and 
(of course) are seemingly confined to regions of NZ where tree cankers are present.  The weather data 
presented in Annex2 of the NZ FWS would accord with a low incidence of fruit infection, and, based 
on Wilson's (1966) observations in California, even  conidial production from stem cankers may be 
sparse during summer.  It is perhaps significant that in what was described as an epidemic of canker in 
Auckland that Brooke& Bailey (1965) only found occasi onal fruit rots.  Unfortunately that paper does 
not record whether the rots were found before or after harvest. 
362. It is extremely unlikely that in the event th at spores deposited on the open surface of fruit at 
or before harvest would play any pa rt in an entry pathway (see Q49). 
Question 58 
Please comment on whether the conclusions in Aust ralia's IRA as to the establishment and spread of 
European canker are objective and credible on the bas is of the available scientific evidence?  Are 
they based on respected and qualified scientific sources?  (IRA, Part B, pp. 129-145;  paras. 4.87-
4.95 and 4.301-4.325 of New Zealand's FWS;  par as. 645-672 of Australia's FWS;  and R 75 by 
New Zealand) 
 
Dr Deckers
: 
 
363. Comparable with the situation of fire blight, th e chance that an infected  dessert apple fruit can 
establish a new disease in an unaffected orchard and sp read the disease is considered to be rather low.  WT/DS367/11 
 Page 69 
 
 
  Dr Latorre : 
 364. The conclusion of Australia's IRA as to the est ablishment and spread of European canker is 
based on the available scientific evidence.  Ho wever, the information provided is not entirely 
convincing because:  (i) Analysis of the climate c onditions in the potential entrance areas is discussed 
only briefly.  It should not be assumed that any area where the rainfalls are close to, or exceed 1000 
mm annually, are necessarily prone to European ca nker development.  Temperatures and rainfalls 
during the entrance periods (fruit-importing periods) s hould be provided, considering that they will 
affect the likelihood of establishment and spread of N. Galligena after entrance.  Weather information 
for the entrance periods would allow experts to assess the probability that mature fruit carrying latent 
infections will develop symptoms, sporulate, liberate the inoculum and spread it to nearby hosts.  (ii) 
Injuries, leaf scars, pruning wounds, or other damages ar e necessary for infection, but leaf scars in the 
autumn are the most common sites of infection.  Fruit importation (and inoculum availability) could occur when leaf scars are not present, reducing th e probability of establishment and spread to zero. 
Dr Swinburne
: 
 
365. The initial establishment of an epidemic incited by N. Galligena  via imported infected fruit 
has not been demonstrated, as the submissions by both parties acknowledge.  Consequently the issue 
can only be addressed from a theoretical standpoint.  For such a pathway to exist fruit would not only 
have to develop visible rot, but also to form viab le spores which can be distributed to new hosts.  The 
formation of perithecia on fruit has been observed very rarely (Dillon-Western, 1927), and does not 
feature in any subsequent epidemiological study (Swinburne, 1975; CAB 2001).  It is therefore most 
unlikely that ascospores would be formed or release d from rotted fruit.  The formation of conidia on 
the surface of lesions does occur (Swinburne, 1975) generally in the centre of the rotted area where 
the cuticle has split.  This is mo st obvious in fruit taken from stores in which the humidity has been 
maintained at c. 100%.  Fruit which develop rots la ter within the retail chain in conditions with lower 
RH do not usually produce spores (personal observati on) which conforms with the observations (e.g. 
Wilson, 1966) for wood infections, that a period of 'leaf-wetness' is required for conidia formation. 
366. Conidia are dispersed by rain splash, over relatively short distances, especially so from 
ground level.  Thus to successfully transfer infection fruit would have to be very close to a susceptible 
host and have the appropr iate weather conditions. 
367. Subsequent spread of infection from such an  entry point would be dependent on suitable 
weather conditions, [and possibly the genus of the new host (Flack & Swinburne, 1976)].  The first 
requirement for long distance dispersal from the initia l host would be the formation of perithecia and 
the forcible discharge of ascospores; processes wh ich are heavily dependent on rainfall (see Q57).  
The dispute between the parties regarding the suitability  of the climate in the fruit growing regions of 
Australia for the establishment and spread of European canker in a pple is difficult to resolve on the 
basis of the data available.  However, the fact that canker has only been seen  in Tasmania and that 
western Tasmania has a higher number of days of  rainfall (> 1mm) than mainland Australia is 
striking.  Moreover, it may also be significant that even in Tasmania perithecia were not observed.  
Thus it is difficult to escape the conclusion that  the climate of fruit growing regions of mainland 
Australia are not conducive to the developmen t of an epidemic of this disease (see Q72). 
Question 59 
Please comment on the relevance, if any, of data con cerning the volume of apples moving out of the 
Spreyton area during the European canker out break for assessing the risk of apples from 
New Zealand being a vector for European canker into Australia?  (Para. 4.94 of New Zealand's FWS;  
R 78 by New Zealand;  Exhibits NZ-109 and NZ-110) 
 WT/DS367/11 
Page 70  
 
  Dr Deckers
: 
 368. This export of high volumes of apples from a NG infected area confirms the very small 
chance that apple fruits infected with NG can estab lish the disease in non infected regions or spread 
the disease in a new area. 
Dr Latorre
: 
 369. On the basis of the biology of N. Galligena  and considering the epidemiological 
characteristics of European canker, if N. Galligena  were to enter a new area, I would expect a 
relatively slow dissemination of the pathogen and sub sequent spread of European canker in this new 
area.  The information provided in relation to Spreyton supports the hypothesis of a very slow spread 
occurred that would make it possible to eradicate N. Galligena . 
Dr Swinburne
: 
 370. Whatever the volume of apples shipped from the Spreyton area to mainland Australia, the 
absence of information on the percentage of apples infected with N. Galligena,  if any, makes it 
impossible to use the events as a predictor of the likelihood of the disease becoming established 
through this pathway from similar imports from NZ.  Thus it is impossible deduce why these 
Tasmanian fruit shipments did not lead to canker establishment. 
Question 60 
Please comment on whether Australia's IRA provides an objective and coherent analysis of the 
potential consequences of European canker.  Are the I RA's conclusions in this regard, in particular 
the overall consequence rating of "E" (moderate) d esignated by the IRA, objective and credible on the 
basis of the available scientific evidence?  (IRA,  Part B, pp. 145-150;  paras. 4.326-4.332 of 
New Zealand's FWS;  paras. 673-718 of Aust ralia's FWS;  and R 79 by New Zealand) 
 Dr Deckers
: 
 371. It is important to distinguish the situation of a NG outbreak in the different regions of 
Australia and the general estimate the overall conse quence rating of "E" (moderate) seems to be high 
when there are regions where the disease will not  be able to develop due to unfavourable 
climatological conditions like the presence of drought. 
Dr Latorre
: 
 372. On the basis of reports in the literature and the experience of other apple-producing countries, 
the conclusion arrived at by IRA with regard to  the overall consequence rating (E, moderate) is 
overestimated.  (i) European canker has been c onsidered as a major disease of apples, proving 
economically important in Chile (Latorre et al., 2002), primarily because 2-3 fungicide applications 
are necessary each year to prevent infections thr ough leaf scars.  European canker has never limited 
the Chilean commercial production, although yields can be reduced and production cost increased.  
(ii) "Climatic conditions in approximately 40%  of Australian commercial fruit-growing areas are 
conducive to infection."  This conclusion was only based on annual rainfalls, without any analysis of 
the climatic conditions during the critical period (e.g., l eaf fall in autumn) with regard to the host trees 
for infection. (iii)  "The main economic impact of  the disease results from destruction and removal of 
individual trees or whole orchards because of girdling of branches, which can significantly reduce crop production yields …"  Removal of whole orchards of bearing trees is extremely rare, if it ever 
happens.  Removal of some young trees may occur.  (i v) "Fruit rot generally develops in the field or 
before harvest, although storage losses of 10–60% of  the stored fruit crop have been reported in 
various parts of the world."  In rainy ar eas at harvest, storage losses are commonly below  WT/DS367/11 
 Page 71 
 
 
  approximately 2%.  In areas free of summer rains at  harvest, storage losses are 0%.  Storage losses of 
10-60% may occur in highly susceptible apple vari eties that are inadequately managed (without 
fungicide treatments under poor co ld-storage conditions), a phenome non that has been observed only 
in areas with extremely favourable envir onments and under high inoculum pressure. 
Dr Swinburne : 
 
373. The overall consequence rating of 'E' (moderate) can only be justified if the assumption that 
climatic conditions in the fruit producing regions of mainland Australia are conducive to the rapid 
spread of canker from a point source (discarded rotte d apples) across a district.  As discussed in Q58 
& Q66, and in the light of the limited spread expe rienced in Tasmania, it seems unlikely that this 
could occur. 
374. There is one, albeit unlikely, scenario for the rapid dissemination of canker across all apple 
growing regions: that N. Galligena  somehow enters the production system of new trees, and be 
unwittingly sent out to different regions (McCracken et al  2001).  However, as nursery-tree 
production is apparently carried out under quarantin e conditions (Aust. FWS) this seems unlikely. 
375. Discarding the nursery pathway leads to the conclusion that a consequence rating "C" would 
be more appropriate for the impact on plant h ealth.  This would be the worst case scenario. 
Question 61 
Can the likelihood of entry, establishment and sp read of brown rot associated with Japanese nashi 
pears be compared to that of European canker associated with New Zealand apples?  Are there 
respected and qualified scientific sources to support  New Zealand's argument in para. 4.443 of its 
FWS that there is a higher risk profile for Japanese nas hi pears in the context of brown rot than for 
New Zealand apples in the context of European can ker?  Please comment on whether the economic 
and biological impact for the Australian agriculture industry may be different if M. fructigena (brown 
rot) were to establish in Australia than if Euro pean canker were to establish in Australia.  
(Paras. 4.439-4.442 of New Zealand's FWS;  par as. 992-993 and 1001-1004 of Australia's FWS;  
R 101 by Australia)  
Dr Deckers
: 
 376. Brown rot and NG are both important fungal diseases in fruit growing.  The introduction of 
brown rot on pear would surely create a large probl em of rotting phenomena on different fruit species.  
But the introduction of European canker should not only create rotten fruit problems but also 
problems of NG infections on banches or on the root stock and can even kill fruit trees completely .  
The impact of NG on apple is thus more impor tant than the impact of brown rot on pear. 
Dr Latorre
: 
 
377. In my opinion, there is not enough published info rmation to allow an adequate comparison of 
the risk of entrance, establishment and spr ead between brown rot and European canker. 
378. The likelihood of entry of brown rot ( Monilinia fructigena ) on Japanese nashi pears and 
European canker ( N. Galligena ) on apple may be similar, although these diseases are quite different in 
biology and epidemiology.  However, Australia claims that pears are imported only from pest-free 
areas ("areas of freedom"), which I assume was demonstrated previously.  If so, the likelihood of the 
entrance of M. fructigena  drops down considerably, to negligible. 
379. The biological impact of both diseases would be highly dependent on  weather conditions 
during fruit maturity.  Among other factors, the seve rity of both diseases depends on the presence of WT/DS367/11 
Page 72  
 
  frequent rains during harvest.  If this is accepted, the economic and biological impact on Australian 
agriculture, particularly for apple a nd pear production, would be similar. 
380. The arguments provided by Australia (FWS 1003 and 1004) are rather weak:  (i) Brown rot 
rarely causes economical losses, unless frequent summer rains occur, it is weather dependant.  The same is true for European canker.  (ii) Severa l of the fungicides used to prevent apple scab 
(V. inaequalis ) can also control European canker. 
Dr Swinburne
: 
 381. The risk posed by brown rot incited by M. fructigena  differs from that associated with 
N. Galligena  in a number of important respects.  For exam ple, it can spread from fruit to fruit in bulk 
bins leading to "nesting", and thus inocul um enhancement, which is not found with N. Galligena .  
Rotted fruit almost invariably produce prolific num bers of conidia on sporodochia which form in 
concentric circles across the surface of the rotted ar ea.  The conidia are dispersed by wind alone and 
are thus not reliant on rain-fall.  This contrasts with N. Galligena  in which spore production is 
relatively low and the spores are dispersed by rain  splash (Byrde & Willetts, 1977; Swinburne 1975). 
382. As stated in the NZ FWS, the host range of M. fructigena , including as it does fruit types of 
importance to Australia, also suggests that it poses a greater risk to commerce than N. Galligena .  But 
if the Japanese pears are indeed coming from localities verifiably free of the disease then perhaps the 
risk is small. 
Question 62 
Please comment on the alternati ve measures proposed by New Zealand in respect of European 
canker, namely (i) restricting imports to apples sour ced from "pest-free places of production", to be 
determined by a single inspection of each expor ting orchard and maintained through controls on the 
subsequent movement of nursery stock, or (ii) limitin g imports to apples sourced from areas of "low 
pest prevalence", to be determined by inspection of a sample of orchards.  How do these alternative 
measures compare to the relevant requirements imposed by Australia  in terms of risk mitigation?  
(IRA, Part B, pp. 4-5 and 150-155;  para. 4.4 91 of New Zealand's FWS;  and paras. 1087-1088 of 
Australia's FWS) 
 
Dr Deckers
: 
 383. A pest free place of production or an area of low pest prevalence will not be easy to guarantee 
because NG is often spread by the importation of young apple trees where aswell the apple variety as 
the rootstock can be infected by the NG disease.  Restricting the imports of apples to the pest free 
places or to the areas with low pest prevalence, toge ther with the application of a fungicide schema 
during bloom will seriously reduce the risk of  importation of internally infected fruits. 
Dr Latorre
: 
 
384. Both alternative measures, "pest-free places of production" and "low pest prevalence," can 
mitigate the risk of N. Galligena  entrance via asymptomatic fruits.  These are acceptable methods 
which should be implemented according to FAO (ISPM  4, 10, 22).  The New Zealand proposition is 
less restrictive, economically feasible, and shoul d not affect the application of phytosanitary 
procedures to mitigate the risk of N. Galligena  entrance via the importation of mature apples. 
Question 63 
Please comment on whether the alternative meas ure proposed by New Zealand in respect of 
European canker, namely to require that New Zealand export to Australia only "mature, symptomless 
apples", would achieve Australia's appropriate level  of phytosanitary protection (ALOP).  How does  WT/DS367/11 
 Page 73 
 
 
  this alternative measure compare to Australia's me asures in terms of risk mitigation?  (IRA, Part B, 
pp. 4-5 and 150-155;  paras. 4.492-4.512 of New Zealand's FWS;  and paras. 1082-1086 of 
Australia's FWS) 
 
Dr Deckers : 
 
385. Mature symptomless apple fruits can be internal ly infected by NG and will not be able to 
fulfil Australia's ALOP. 
Dr Latorre : 
 
386. Exporting only "mature asymptomatic apples" from New Zealand would disregard the fact 
that latent infection may occur on a mature apple fruit, the main issue of this dispute.  Latent infection 
(fruits that are infected but asymptomatic at ha rvest) may be extremely rare in New Zealand, 
considering that weather conditions at harvest ar e not very favourable for European canker in New 
Zealand apple-producing areas, as previously discussed.  However, it has to be admitted that the 
likelihood of such an occurrence is  close but not equal to zero;  at  least, until objective results prove 
otherwise. 
Dr Swinburne (Response to questions 62 and 63) : 
 387. The difficulty of responding to these questions arises from the presence of flaws in the 
arguments from both parties. 
388. New Zealand relies on the contention that if fruit of  the varieties to be traded were infected 
during development the disease would become visible at or before they reach harvestable-maturity and that consequently there would never be quiescent (l atent) infections that could not be eliminated 
before shipment.  Experience elsewhere indicates that this is not correct (see Q55/6).  That is not to 
say that NZ fruit will develop post harvest rots, as this will depend on (a) the presence of the disease 
in the trees harvested and (b) the climate during the summer season.  Given that some 95% of NZ 
orchards are either disease free or have very low levels  of infection, coupled with a climate that is not 
well suited to summer fruit infection, it necessarily follows that the probability of there being post 
harvest rots is very low indeed.  Exclusion of exports from the remaining 5% of orchards would 
reduce the risk to insignificance. 
389. Australia's insistence on receiving only fruit from inspected orchards certified as free from 
canker would eliminate virtually all risk of fruit be ing infected.  Moreover, as there is no evidence to 
support Australia's concerns that cross contamina tion might occur in the pack house during grading 
etc. no further measures would be necessary. 
Question 64 
Please explain with reference to respected and qual ified scientific sources, the potential pathways for 
long distance spread of European canker.  How ar e the planting of infected nursery stock and the 
movement of apple fruit relevant to long distance spread of European canker?  (Paras. 3.65 and 4.95 
of New Zealand's FWS) 
 
Dr Deckers
: 
 
390. The movement of infected nursery stock is the main way for a long distance spread of the NG 
disease and will directly infect the newly planted orchards. WT/DS367/11 
Page 74  
 
  391. The infected fruits can be exported as mature de sert apple fruits and spread also over long 
distances but need to meet a host plant in a susceptible stage before  an infection can take place and 
this last step has a rather  low likelihood to occur. 
Dr Latorre
: 
 
392. On the basis of current information, the main  acceptable pathway fo r long-distance (e.g., 
between countries) dissemination of European canke r is the movement of infected plant material 
(nursery stocks) (AUS-2BA p. 142).  Recently, a st udy conducted in the UK concluded that about 6% 
of the infection in new orchards could be associated with infected nursery stocks (McCraken et al., 2003b).  There is no scientific evidence demonstrating that long-distance spread of European canker is 
due to the movement of fruits.  Eventually, coni dia and ascospores can develop in rotted fruits and 
contribute to local spread (tree-to-tree movement).  Therefore, long-distance spread along with mature 
apple fruits should be regarded as a hyp othesis rather than a true fact. 
Dr Swinburne
: 
 
393. There is no data that confirms or refutes that  rotted fruit forms a pathway for the long distance 
transport of infection with N. Galligena , (see Q54).  Virtually all research publications emanate from 
countries in which the disease is essentially endemic (CAB, 2001), so it is not surprising that the focus 
has been on more obvious routes, such as orchard to  orchard, and hedge-row to orchard.  However, 
the possibility that disease could be transmitted asym ptomatically in maiden or two year old trees 
from the nursery has been confirmed (McCracken et al 2001).  In terms of long distance transport this 
could be very significant, especially for regions in which the apple itself is a recent introduction, and 
where by definition the pathogen is/was not endemic. 
Question 65 
Please comment on whether there are respected and qualified scien tific sources to support the 
position in Australia's IRA that latent infecti on with N. Galligena can occur in mature, dessert 
varieties of apples, including in New Zealand.  Please comment on whether there is any scientific 
evidence of latent infections occurring in mature apple fruit, including in New Zealand.  (Paras. 4.61-
4.68 and 4.272-4.274 of New Zealand's FWS;  para. 613 of Australia's FWS) 
 
Dr Deckers : 
 
394. In Europe the latent infection of NG can occur in  mature dessert apple varieties;  this does not 
mean that the same s ituation will occur in certain area of New Zealand apple production under 
comparable climatological situations. 
Dr Latorre : 
 
395. Considering that fruit rots occur in New Zeala nd (NZ FWS, Paras. 4.60) and despite the fact 
that this a very rare event, latent infection in ma ture fruits cannot be ruled out.  It is possible that 
asymptomatic but infected mature apples could de velop symptoms and eventually sporulate during 
transit and commercialization in Australia.  However, I would consider the probability of this event as 
extremely low to negligible.  Please notice that N. Galligena  was not found in a small apple sample 
(53 apples) from New Zealand, intercepted by Australia's authorities between 1988 and 2003 (AUS-2 
BA p. 123).  Nevertheless a large apple sample s hould be studied before reaching a final conclusion. 
Dr Swinburne : 
 396. See Q55.  WT/DS367/11 
 Page 75 
 
 
  Question 66 
Please comment on whether research relating to European canker in Europe and North America 
relied upon by Australia's IRA is relevant to the c limatic conditions for the entry, establishment or 
spread of the disease in Australia.  Are the cl imatic conditions regardi ng European canker in 
Australia comparable to those in the countries in  which the research has been carried out?  How 
relevant is this research to evaluating the risks of N. Galligena associated with apples from 
New Zealand?  (Paras. 2.13, 4.63, 4.68, 4.73, 4. 87-4.91, 4.315 and 4.321 of New Zealand's FWS;  
paras. 570-574 and 627 of Australia's FWS) 
 
Dr Deckers : 
 
397. The specific conditions for entry, establishment and spread can be substantially different 
between the European climatic conditions and the conditions in Australia.  These differences can be 
decisive for the behaviour of a fungal disease in a c ountry.  The amount of rain is an important factor 
but also the distribution of this rain throughout the season is even more  important for the development 
of the NG fungal infection in an area. 
Dr Latorre : 
 398. This information is a key point in assessing the risk of establishment and spread of 
N. Galligena  associated with asymptomatic apples from New Zealand.  Climatic conditions in 
Australia's apple-producing regions must be suita ble to disease establishment and spread, otherwise 
the likelihood of establishment and spread would be zero and the risk analysis should end at this 
point.  Additionally, favourable  climatic conditions are compul sory for sporulation (inoculum 
production, mainly conidia), dissemination and su rvival of the inoculum.  The environmental 
information provided by New Zealand suggests th at temperatures and rainfalls are relatively 
unfavourable for N. Galligena  during summer and early fall in Australia, which may be the most 
critical period for infection (Figure 2, NZ FWS paras. 4.91).  If this is the situation, the likelihood of 
establishment and spread should be extremely low to negligible. 
Dr Swinburne
: 
 399. Data from Northern Europe, California and Chile on the basic weather conditions for 
infection (in the strict sense) have been dete rmined from artificial inoculation experiments 
(summarised in Swinburne, 1975; CAB 2001, and Latorre et  al 2001).  This data w ill be relevant to all 
apple growing regions, but as they refer to just one asp ect of the cycle of events, can not be used alone 
to predict the suitability of any region for the disease .  The essential weakness of the approach in the 
IRA is that it assumes that inoculum (spores) for infec tion is always available, and all that is required 
is a suitable period (hours of leaf wetness within give n temperature limits) for infection to occur.  The 
major flaw in this argument is the assumption that  regions can be compared on the basis of annual 
rainfall, without regard to rainfall patterns.  Even in regions such as N. Ireland (Loughgall) with rain 
in all seasons, more than 5hrs of leaf wetness was required following a few dry days before ascospore discharge resumed (Swinburne, 1971b).  The situation in regions with a pronounced dry season, such 
as California and the Pacific Northwest in the USA,  spore formation does not even begin until some 
time (as yet undetermined) into the rainy period (Zeller, 1926, Wilson, 1966/8).  For such an area data 
relating only to simple "infection periods" woul d greatly overestimate the risk of disease 
establishment.  (see Q72 for an appraisal of weather data in both FWS). WT/DS367/11 
Page 76  
 
  Question 67 
Please comment on whether Australia's IRA prov ides an objective and coherent analysis with respect 
to conidia and ascospore production and dispersal in light of climatic conditions in New Zealand's 
apple-growing regions during harvest time.  Are there respected and qualified scientific sources to 
support the view that mature apple fruit can be in fested (surface contaminated) with spores at 
harvest, including via wind currents?  Please comment on whether these spores could later infect the 
apple? What is the impact, if any, of climatic conditions in this regard.   Is the evaluation contained in 
Australia's IRA regarding these points objective and credible on the basis of the available scientific 
evidence?  Is it based on respected and qualified scientific sources?  (IRA, Part B, pp. 122 and 
124-125;  paras. 4.65-4.68 and 4.278-4.281 of New Zealand's FWS;  and paras. 542-552 and 635-636 
of Australia's FWS)  
Dr Deckers
: 
 400. Infection of the apple fruits by spores at harv est time should be only with the conidiospores 
while there are no ascospores available at that time.  The conidiospores will spread more locally and 
can infect the fruits by the stalk end of the fruits  where water can be present for a longer time during 
the preharvest period during a rainy period.  Dist ribution of these conidiospores over a long distance 
by wind is rather unlikely. 
Dr Latorre
: 
 
401. Australia does not provide objective data rega rding spore (conidia, ascospore) production and 
release under the environmental conditions of New Ze aland.  There are not qualified scientific sources 
to support the view that mature apple fruit can be  infested (surface-contaminated) with spores at 
harvest, including via wind currents.  If this event would happen it would be ex tremely rare and would 
not necessarily result in infected fruits, unless enough spores land on damaged mature fruits.  Conidia 
are not wind dispersed;  they are dispersed by rain s and rain-splash.  Ascospores can be dispersed by 
wind currents to rather short distances (metres from the inoculum source).  However, it would be possible that rain-splashes containing spores may be carried several metres by winds.  In my opinion 
this analysis overestimates the risk of inoculum dispersal. 
Question 68 
Please comment on whether Australia's IRA took  into account respected and qualified scientific 
sources in arriving to the view that, if spores were  to be dispersed by rain onto the surface of a 
mature apple immediately prior to or during harvest, they could survive without continued moisture.  
Is this conclusion objective and credible on the basis  of the available scientific evidence?  (IRA, 
Part B, pp. 124-125;  paras. 4.67 of New Zeal and's FWS;  and paras. 554-557 of Australia's FWS) 
 Dr Deckers
: 
 402. Conidiospore production can take place around sporulating cankers in the orchard and rain is 
necessary to spread the spores from the cankers to  the fruits.  Once on the fruits the spores can be 
accumulated on the fruits in a natural way in the cavity around the stalk or around the calyx and realise later on an infection. 
Dr Latorre
: 
 403. Based on the available scientific reports, this c onclusion has no credibility.  Puia et al. (2004) 
(AUS-56) is the only published report that addr esses superficial contamination.  "…When dessert 
apple varieties were monitored from the beginning of storage in November until the end of storage in 
April in Romania, N. Galligena  was isolated from the surface, insi de and even the locules of the  WT/DS367/11 
 Page 77 
 
 
  fruit."  However, the Materials and Methods used by Puia et al. (2004) (AUS-56) do not allow the 
authors to conclude that N. Galligena  was on the surface of the fruits. 
Dr Swinburne (Response to questions 67 and 68) : 
 404. The contention that fruit could become contamin ated by spores at harvest depends on their 
presence on tree cankers during any period of rain at that time.  It is extremely unlikely that these 
would be ascospores as even in the wetter summers of  Europe perithecia are usually in produced in 
winter to spring (Swinburne 1975).  The production of conidia in summer (including harvest) is dependent on rainfall (see Q66).  That some conidia production during summer does occur is 
indicated by the detection of fruit rots in NZ, al beit rarely.  These spores would be deposited in rain-
off within the affected tree (Swinburne, 1971), or less likely from a neighbouring tree by splash 
dispersal (Munson 1939).  Wind dispersal releases so few viable conidia (Swinburne, 1971) that these 
can be discounted. 
405. As discussed in Q49 it is most unlikely that conidia which simply contaminate the surface of 
fruit would play any part in an infection pathway. 
Question 69 
Please comment on whether Australia's IRA took  into account respected and qualified scientific 
sources in arriving to the view that mature symptomless apple fruit, infested or latently infected with 
the causal organism for European canker, coul d produce conidia or ascospores in Australian 
conditions.  Is this conclusion obj ective and credible on the basis of th e available scientific evidence?  
(IRA, Part B, pp. 123-124, 127 and 134-135;  par as. 4.78-4.84 and 4.305-4.308 of New Zealand's 
FWS;  and para. 614 of Australia's FWS)  
Dr Deckers
: 
 406. The chance for a successful introduction of NG into Australia by the importation of infected 
fruit is much lower than for the importation of an  infected fruit tree.  Depending on the climatic 
conditions after introductio n and on the presence of a susceptible ho st the transfer of the NG from an 
infected fruit to the susceptible host will be the critical point. 
Dr Latorre
: 
 407. The available information demonstrating that mature asymptomatic apples (infected or 
latently infected) can readily sporulate under the Australian environment is not provided.  Based on 
published scientific information, Australia assumes th at fungal growth and fruit rot resume when fruit 
is removed from cool storage, sold to consumers and stored at room temperature.  Therefore, rotted fruits discarded near susceptible hosts could be po tentially (but not necessarily ) a source of inoculum 
(mainly conidia) for infections in new areas.  Th is conclusion is acceptable and likelihood values for 
establishment and spread in Australia have been assigned (Table 34, AUS-2BA p.144).  However, the 
likelihood assigned seems to be high and these values have not been validated locally.  Based on the 
general information available, I would assume th at these events have a likelihood of occurring 
different from zero, but still extremely low. 
Dr Swinburne
: 
 
408. As discussed in Q58 rotted fruit incubated under conditions of high humidity can produce 
conidia, but it is extremely unlikely that they wo uld produce perithecia, still less that ascospores 
would be released.  The importance of high humid ity to conidia production has to be stressed.  The 
surface of fruit held in cold stores is usually moist,  and fully developed rots usually produce conidia.  
Fruits rotting subsequently in retail packs or in a domestic environment at less than 100% RH are not WT/DS367/11 
Page 78  
 
  likely to produce conidia.  In the uncertain event that an apple shipped to Australia from New Zealand 
rotted with N. Galligena  its ability to act as vector of disease would depend on the handling system on 
arrival. (See Q52) 
Question 70 
Please comment on the relevance of peritheci a on rotting, mummified apples on the ground to the 
spread of European canker.  Please also comment  on whether Australia's IRA took into account 
evidence from respected and qualified scientific s ources regarding whether apple fruit (of either 
dessert or non-dessert variety) develop peritheci a, including in New Zealand.  (IRA, Part B, 
pp. 134-136;  paras. 4.83, 4.86 and 4.304-4.317 of  New Zealand's FWS;  and in paras. 614-626 of 
Australia's FWS) 
 
Dr Deckers
: 
 409. Swinburne clearly indicates that overwintering mu mmified fruits can form  perithecia that can 
produce ascospores that can spread over a longer distan ce than the conidiospores.  Critical point here 
will be the climatic conditions in both countries Ne w Zealand and Australia:  will there be a suitable 
situation for the spores to be produced and w ill this be followed by an infection scenario. 
Dr Latorre
: 
 410. It is possible that perithecia play a minor role in the establishment and dissemination of 
N. Galligena  from rotted fruit, if this ever happens.  On my opinion, there is not enough scientific 
evidences supporting the role of perithecia (ascospor es), eventually developed on rotted fruits, on the 
overall epidemiology of European canker. 
Dr Swinburne
: 
 411. See Q58. 
Question 71 
Please comment on whether Australia's IRA took  into account respected and qualified scientific 
sources in arriving to the conclusion that conidia on  the surface of mature apple fruit can survive cool 
storage without drying out, and germinate once the fruit has been warmed to ambient temperatures 
following removal from cold storage.  Is this conclusion objective and credible on the basis of the 
available scientific evidence?  (IRA, Part B, pp. 13 4-135;  paras. 4.84 of New Zealand's FWS;  and 
paras. 619-621 of Australia's FWS)  
Dr Deckers
: 
 412. Fruit rot caused by NG can be present in a latent form and come out only after some storage 
period.  Conidia themselves have a limited possibilit y to survive on the fruit skin surface and will dry 
out easily. 
Dr Latorre
: 
 413. The information provided does not demonstrate that conidia can survive cool storage on the 
surface of apple fruits.  Australia states that cool storage and transport processes would not adversely 
affect the viability of the fungus.  This may be true only for the fungus inside the fruit but not for 
conidia, mycelia or even ascospores on the surface of the fruit.  In other words, mycelia can survive in 
latently infected fruits;  growth may resume af ter cool storage and eventually the fungus may 
sporulate on the surface of mummified fruits.  WT/DS367/11 
 Page 79 
 
 
  Dr Swinburne : 
 414. See Q49. 
Question 72 
Please consider the two annexes provided by the Parties – Annex 3 to New Zealand's FWS and 
Annex 2 to Australia's FWS – and explain to what extent these documents a ccurately describe the 
climatic suitability for establishment of European canker.  In particular, please comment on whether 
Australia's IRA objectively and coherently takes into account whether New Zealand has weather 
conditions favourable for fruit infections by N. Galligena during the summer (December to February).  
Please also comment on whether Australia's IR A objectively and coherently takes into account 
whether the climate in Australian apple produc tion areas is conducive to the establishment and 
spread of European canker.  (Par as. 4.57-4.58, 4.88-4.90, 4.425 and 4.315 of, and Annex 3 to, 
New Zealand's FWS;  paras. 534 and  627-628 of, and Annex 2 to, Australia's FWS;  para. 15 of 
Australia's opening statement;  and R 77 by Australia) 
 Dr Deckers
: 
 415. Weather data should be examined in detail pe r region and the estimation of NG infections 
should follow this regional approach for both countries. 
Dr Latorre
: 
 
416. The models present in both documents (Anne x 2 AUS FWS and Annex 3 NZ FWS) can be 
used for describing and analysing the relativ e weather suitability of European canker for 
establishment and development.  The weather anal ysis performed by New Zealand (Beresford and 
Kim) objectively explains the algorithm used, and provides information regarding the model's 
validation, using historical weather data obtaine d in five countries where European canker affects 
apples, with different prevalence and severity.  Therefore, it is an acceptable criterion to assess 
weather conditions for European canker establishmen t in Australia, relative to other apple-producing 
areas in the world where N. Galligena  is a real problem.  This does not discount the possible use of 
Climex or other models. 
417. According to these results, it is possible to conclude that: 
(a) Grove (1990) generalization stating that areas  where average annual rainfall is greater 
than 1,000 mm favour establishment of Eur opean canker should not be interpreted as 
a threshold for the establishment of this apple disease.  In fact, there are several places in the world characterized by mean annual rainfall far below 1,000 mm where European canker occurs as a major disease.  As an example, European canker affects 
apples to the extent that chemical control measures are needed in orchards located 
south of Curico-Talca (34º58' S), Chile, wh ere the mean annual rainfall is near 700 
mm, but frequent rains occur during leaf fall, favouring disease infection. 
(b) Based on rainfall patterns, two critical periods for infection by N. Galligena  can be 
defined for apples:  a. Autumn infections associated with leaf fall and infection through leaf scars.  b. Summer infection associated with fruit infection around the time of harvesting, through the calyx end of  the fruits.  In some places, rainfalls and 
temperatures are conducive for autumn infe ctions (e.g., California, Chile), while 
summer infections are prevalent in other apple-producing areas (e.g., United Kingdom).  Based on this weather analysis, weather conditions are relatively less conducive during the summer as compared to autumn for infections in New Zealand. WT/DS367/11 
Page 80  
 
  (c) Following the same analysis, areas poten tially conducive to European canker 
establishment were detected in Australia.  Weather conditions were more conducive 
for infection during autumn as compared to summer.  Overall, the climate in 
Australian apple production areas is relatively less conducive to the establishment and spread of European canker than ot her producing areas of the world. 
Dr Swinburne
: 
 418. In the absence of a fully descr iptive epidemiological model for the establishment of canker 
the approach adopted by Beresford and Kim (Ann ex3 NZ FWS) is both rational and reasonable, 
drawing as it does on the climatic factors identifie d in California and Chile (see Q66).  Most 
importantly it makes allowances for the water requirements for spore formation as well as their 
dispersal and the infection process itself.  In the abse nce of leaf wetness data, an analysis of the days 
of rain during critical parts of the season seems to provide a reasonable assessm ent of infection risk.  
That this model also enables regions within NZ  to be distinguished on the basis of known disease 
incidence is reassuring. 
419. Total annual rainfall is an unsatisfactory measur e of infection risk, but is relied upon heavily 
in the IRA and in the arguments presented in Annex 2 of Australia's FWS (see Q56).  To illustrate this 
point;  the mean annual rainfall in Loughgall, Nort hern Ireland is 800mm, and in Sonoma, California 
it is slightly higher at 900mm (Table1 Annex 3 NZ FWS).  Whilst canker is a sporadic problem in 
California, in Northern Ireland it is a limiting factor  in apple production, constraining the growers to 
mainly one cultivar, Bramley's Seedling, which has gr eater tolerance to this disease than dessert types.  
The difference between these regions can not be account ed for by annual rainfall, but must be related 
to the season in which it falls.  In Loughgall rain is  evenly distributed through the year with few 
prolonged dry periods, in California it falls mainly in winter, when the host is dormant.  Spores are 
produced all year long in Northern Ireland (S winburne, 1975), but not in California (Wilson 1966). 
420. In the absence of a detailed explanation of th e CSIRO climate model, or why the results it 
produced (Annex 2 Aus FWS) differed from the appl ication of the Beresford & Kim model (Annex 3 
NZ FWS) it is difficult to provide critical comment on the potential areas of risk claimed (Fig1 Aus FWS Annex 2).  However, the use of the Beresfor d & Kim model does imply that the climate of the 
coastal cities of Melbourne and Sydney could margina lly support infection in spring and autumn (Fig 
10 Annex 2 Aus FWS). 
421. The scarcity of reports of fruit infection in  NZ, even from districts with canker (e.g. 
Auckland) must reflect the predominant weather c onditions in summer, as contended in Annex 3 (NZ 
FWS).  The relatively low number of days of rain fall in the principle fruit growing areas of mainland 
Australia also suggests that this disease would not spread as aggressively as is contended in the IRA or Annex 2 (Aus FWS). 
Question 73 
Please comment on whether the rea soning in Australia's IRA with respect to the dispersal range for 
conidia is objective and coherent.  Given weather conditions in the territories of Australia and 
New Zealand, are the conclusions in this regard obj ective and credible on the basis of the available 
scientific evidence?  Are they ba sed on respected and qualified scientific sources?  (IRA, Part B, 
pp. 135;  paras. 4.85-4.86 and 4.311-4.313 of New Zealand's FWS;  and paras. 615 and 635-636 of 
Australia's FWS) 
 
Dr Deckers
: 
 422. The chance for a NG infection st arting from the conidiospores pr oduced by an infected fruit 
will not be high in both countries.  WT/DS367/11 
 Page 81 
 
 
  Dr Latorre : 
 423. Although the reasoning in Australia's IRA with r espect to the dispersal range for conidia was 
objective and coherent and based on respected a nd qualified scientific sources, the information 
provided demonstrates only that conidia (and possibly ascospores) of N. Galligena  are short-distance 
disseminated.  Conidial dispersal can be expected  within the infected tree (rain-splash and runoff), 
from infected trees to healthy neighbouring trees (splash, wind-splash), and between neighbouring 
orchards (wind-splash).  There is no scientific re port demonstrating that conidia can be dispersed 
between districts, countries or continents. 
424. I agree that "dispersal for any significant distance is unlikely to occur when ascopores are 
produced by perithecia on an apple on the ground wher e they are less likely to become airborne" (NZ 
FWS paras. 4.86).  However, experimental evid ence is necessary in suppor t of this conclusion. 
425. "Even if latently infected New Zealand fruit could produce spores in the Australian 
environment, these spores would need to be transferred to the host plant.  Any dispersal of conidia would primarily be by rain splash and would like ly only be a few metres from a discarded apple (NZ 
FWS paras. 4.311)."  This is a credible conclu sion supported by experimental evidence, published 
previously.  Therefore, the analysis of the probab ility of establishment and spread of European canker 
after entering Australia should consider that suita ble hosts must be close (a few meters) from the 
inoculum source.  Otherwise, the analysis woul d be overestimating the risk of establishment and 
spread. 
Dr Swinburne
: 
 
426. It is most unlikely that rotted fruit would pr oduce ascospores so they need not be considered 
further here (see Q58).  The dispersal distances for rain splashed conidia quoted in the literature 
referred to in Australia's IRA are the maximum es timates, and refer to conidia released from tree 
cankers above ground level.  For a fruit rotting on  the ground it is reasonable to expect that the 
distances would be smaller, as argued in the NZ FW S.  There are no studies that can accurately guide 
this judgement, but it is unlikely that this would be mo re than a few meters, horizontally or vertically.  
It must be evident that for splash dispersal to operate from a rotted apple on the ground the lesion has 
to be facing upwards; thus subject to further chance. 
427. For such dispersal to lead to an infection an y adjoining host has to have sites receptive to 
conidia.  The NZ FWS (4.311-4.313) disputes the cl aim made in the Aus FWS that leaf scars remain 
susceptible for weeks after leaf fall, basing ther e argument on Wilson (1966).  All studies made under 
field conditions conclude that leaf scars are sus ceptible only for a few hours after leaf fall (reviewed 
in Swinburne, 1975), leading to the conclusion that the growth cabinets used by Wilson lead to conditions not normally encountered in nature. 
Question 74 
Please comment on the relevance, if any, of th e Tasmanian outbreak of European canker for any 
conclusions on the existence of pathways and the suitability of Australia's climate for the 
establishment and spread of European canker.  (IRA,  Part B, pp. 135;  paras. 4.92-4.94, 4.308 and 
4.323 of New Zealand's FWS;  paras. 627-632 of Australia's FWS;  and R 75-76 by the Parties) 
 
Dr Deckers
: 
 
428. The fact of the Tasmanian outbreak of NG does not  mean that the climate there is suitable for 
a NG infection.  It is even surprising that it was po ssible to eradicate this infection in the area;  this 
means that the climate condition for NG was surely  not so good for an optimal development of the 
fungal disease. WT/DS367/11 
Page 82  
 
  Dr Latorre
: 
 429. The Tasmanian outbreak demonstrates only that climate conditions are suitable for European 
canker there.  The lack of considerable spread s uggests that weather conditions are not favourable for 
European canker in Tasmania (Spreyton, Tasman ia, AUS FWS Annex 2;  Beresford and Kim, NZ 
Annex 3).  These relatively unfavourable climatic conditions may imply that prevalence, incidence 
and severity of European canker remained low and th at the disease never spread considerably outside 
Tasmania.  However, these observations do not n ecessarily support the conclusion that the weather 
conditions are unsuitable for European canker in th e rest of Australia, as indicated by New Zealand 
(ZN FWS paras. 4.92):  "The outbreak of European canker in Tasmania (an area where conditions are 
marginally favourable to European canker) confirms the unsuitability of the rest of Australia to the 
disease." 
Dr Swinburne
: 
 430. The Tasmanian outbreak of European canker does have some relevance to the suitability of 
the climate in mainland Australia to support an epid emic.  The fruit growing areas in the west of the 
island "enjoys" more days of rain than Auckland (N Z) and yet the reports suggest that the impact of 
the disease in terms of severity or spread over a period of years was less in the Spreyton district than now seen in Auckland.  The Beresford & Kim mode l (Annex3 NZ FWS) strongly suggests that this 
difference is attributable to unfavourable temper atures in Tasmania, and thus providing further 
support to its use in assessing the disease potential of differing climatic zones. 
431. (See Q59 for relevance of fruit shipment s from Tasmania to mainland Australia). 
Question 75 
Please comment on the likelihood values and distribution included in Australia's IRA regarding importation step 2, concerning mature apple being inf ested or infected with N. Galligena (uniform 
distribution with a minimum value of 1 x 10E-6, and a maximum value of 1 x 10E-3). 
 
Dr Sgrillo
: 
 432. The conclusions of the IRA are summarized as follow: 
"… IRA Team focused on the fact that under New Zealand conditions fruit is only 
occasionally attacked and this generally r esults in rotting of the fruit.  Rotted fruit 
would not be picked.  There is some like lihood of fruit getting infected late in the 
season and remaining latent, but this likelihood would be extremely low."
53 
"... fruit infection is very unlikely to occur."54 
433. It seems evident that the IRA Team is referring to a number of fruits belonging to a 
population. 
434. The minimum and maximum values that were c hosen represent a "per fruit" probability.  
When the population is viewed the results generated are much greater than "extremely low" and "very 
unlikely to occur".  If a population of 200.000.000 fruits is considered then from 200 to 200.000 fruits would be infested/infected by N.galligena  what seems to be too high for an "extremely low" category.  
The parameters chosen should reflect the cat egory concepts also in populational terms. 
                                                     
 
53 (footnote original ) IRA p. 123. 
54 (footnote original ) IRA p. 122.  WT/DS367/11 
 Page 83 
 
 
  Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based 
on respected and qualified scientific sources?  Does this evaluation fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  (IRA, Part B, pp. 121-123;  paras. 4.270-4.275 of New Zealand's FWS;  and paras. 529-547 of Australia's FWS) 
 
Dr Sgrillo
: 
 435. The scientific evidence is based in respected a nd qualified papers;  however there is no factual 
information to support the choice of 1E-6 and 1E -3 as, respectively, th e minimum and maximum 
parameters of the distribution. 
Dr Deckers (Response to whole question)
: 
 436. This value is an estimation of the risk situati on and looks to be high surely when the fruits are 
coming from orchards in New Zealand where no active NG infections occur. 
Dr Latorre (Response to whole question)
: 
 437. The Australian IRA's assessment regarding the likelihood of a mature apple being infested/ 
infected with N. Galligena  (importation step 2) (AUS-2 p. 121 and 123, Table 12) was considered 
extremely low-risk.  The probability assigned varied from 10
-6 to 10-3.  However, the midpoint 
(5x10-4) was used because a uniform distribution was assumed.  On the basis of the information 
provided, the probability criteria were selected arb itrarily to allow semi-quantitative analysis, but no 
experimental data supporting these values were presen ted.  Several scientific sources were cited, but 
none of them report information regarding the fr equency of apple infec tion and latency in New 
Zealand or elsewhere.  Considering the epidemiol ogical characteristics of European canker, the 
probability intervals given in Table 12 are too conservative for areas with dry summer conditions, 
although they may be acceptable for areas with fr equent summer rains.  Therefore, the figures may 
overestimate the likelihood of each event to occur under dry summer c onditions, particularly if fruit 
infection is extremely close to zero. 
Dr Swinburne (Response to whole question) : 
 438. In the absence of definitive data from surveys of fruit rots (post harvest) the assignment of 
any probability value to likelihood of the presence of quiescent infections in shipped fruit must be 
arbitrary.  Both parties seem to agree that the fre quency of fruit rotting is low, given the paucity of 
positive identifications.  That this is so, even from regions with tree cankers (e .g. Auckland) this must 
be attributable to unfavourable weather conditions , especially the absence of rain, during the summer 
months. 
439. The implication of there being one infected fru it per thousand (max), coupled with the fact 
that 95% of exported fruit comes from orchards with little or no tree cankers (IRAb p121), is that fruit 
from infected orchards has in the order of 2% apples that will rot with N. Galligena  each year.  That 
this would escape the attention of research centres in NZ seems extraordinary, if true. Alternatively, 
the arbitrary probability maximum set in the IRA is too high. 
Question 76 
Please comment on whether the reasoning in Australia' s IRA with respect to the possibility that latent 
infections of N. Galligena may occur in matu re New Zealand apple fruit and not become apparent 
until after storage is objective and coherent.  Are th e conclusions in Australia's IRA in this regard 
objective and credible on the basis of the available scientific evidence?  Are they based on respected WT/DS367/11 
Page 84  
 
  and qualified scientific sources?  (Paras. 4.61-4. 68 and 4.272-4.274 of New Zealand's FWS;  
para. 538 of Australia's FWS;  and para. 56 of New Zealand's opening statement) 
 
Dr Deckers
: 
 
440. I am convinced that latent infections of NG may occur in mature New Zealand apples and not 
become apparent until after storage.  Probably there are significant differences between different 
apple varieties for these latent infections of NG. 
Dr Latorre : 
 
441. The reasoning in Australia's IRA with respect to  the possibility that latent infections of 
N. Galligena  may occur in mature New Zealand apple fruit and not become apparent until after 
storage is based on published information.  Alt hough there is no scientific evidence of latent 
infections occurring in mature New Zealand apple fru it, it is possible to assume that latent infection 
may occur if fruit rot caused by N. Galligena  were to occur.  There is always a concern that fruit rot 
can further develop in cold stores.  It is true th at IRA relies on scientific research about latent fruit 
infection in the UK and Northern Europe, but diffe rences between New Zealand and Northern Europe 
can only be expected in relation to the likelihood of  this event:  very high in Northern Europe and 
extremely low to negligible in New Zealand.  In  this regard, New Zealand can be compared with 
California and Chile, where mature fruit infections are extremely rare or nonexistent because of the 
unsuitability of the weather conditions during summer months. 
Dr Swinburne : 
 442. (See Q55) 
Question 77 
Please comment on whether the reasoning in Australia's  IRA with respect to the view that latently 
infected but symptomless mature apple fruit ma y develop rot and thus generate spores, and the 
relevance of this fact for the possibility of fru it contamination by N. Galligena during picking and 
transport to the packing house, is objective and coheren t.  Are the conclusions in Australia's IRA in 
this regard objective and credible on the basis of th e available scientific evidence?  Are they based on 
respected and qualified scientific sources?  (IRA, Part  B, pp. 123-127 and 134- 135;  paras. 4.70-4.72, 
4.77-4.84 and 4.277 of New Zealand's FWS;  and paras. 538-539, 547-548, 564-565, 578-600, 612-
613, 619-620, 629-630, 639-640 and 666-667 of Australia's FWS)  
Dr Deckers
: 
 443. This contamination of the fruits by sympto mless mature apple fruits during picking and 
transport to the packing house is very low while at  that moment the fungal disease, when present, will 
be present only in a latent phase.  When the rotten appl es are visible at harvest, they will not be picked 
as good quality fruits and will be on the orchard floor. 
Dr Latorre
: 
 444. The reasoning in Australia's IRA with respect to the view that latently infected but 
asymptomatic mature apple fruits may deve lop rot and thus generate spores of N. Galligena  during 
picking and transport to the packing house (although objective) is highly unlikely. 
445. Latently infected fruits develop symptoms befo re producing conidia.  Mummified fruits in the 
autumn may produce ascospores under cool humid ambi ent conditions the following spring, or after a 
prolonged period in cold storage.  However, this is a rare event (<0.5%).  Therefore, conidia and  WT/DS367/11 
 Page 85 
 
 
  eventually ascospores may develop after several week s or months of incubation.  The likelihood that 
these spores may contaminate fruits superficially is  extremely rare, and the probability that spores 
contaminating the surfaces of mature fruits will cause infection is negligible.  In conclusion, fruit 
contamination with spores of N. Galligena  during picking and transport to the packing house should 
be disregarded.  There is no scientific evidence on this subject to strongly support this hypothesis. 
Question 78 
Please comment on the likelihood values and distribution put forth by Australia's IRA for importation step 3 regarding clean fruit being contaminated by  N. Galligena during picking and transport to the 
packing house (triangular distribution between 1 x 10E-6 and 1x 10E-4, with a most likely value of 1 x 10-E5). 
 
Dr Sgrillo
: 
 446. The IRA Team describes hypotheses to explain how a clean fruit could be contaminated by 
N. Galligena .  However there is no factual evidence to  validate theses hypothesis.  There are no 
records of N. Galligena  spores being transferred to clean fruit.
55. 
447. Considering that, also, there is no factual evid ence of a most probable value, the IRA team 
does not explain why the triangular distribution was chosen instead of a uniform distribution. 
448. The IRA Team explains that the chosen values were attributed to the parameters of the 
distribution because "This range allows for a small number of fruit to be contaminated...".56 
449. However, the IRA Team does not define "small nu mber of fruit".  If 10 is a small number of 
fruit then the most probable value would have to be  5E-8 (in a 200 million fruits population) which is 
200 times less than the number chosen by the IRA team. 
Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based 
on respected and qualified scientific sources?  Does this evaluation fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  (IRA, Part B, pp. 124-125;  paras. 4.276-4.281 of New Zealand's FWS;  and 
paras. 548-563 of Australia's FWS) 
 
Dr Sgrillo : 
 450. There is no scientific evidence to support the choice of a triangular distribution and its 
respective parameters. 
Dr Deckers (Response to whole question)
: 
 451. Contamination risk of clean fruit during picking and transport is considered to be very low 
because the spore survival externally  on the fruit skin is limited in time and the spores will dry out 
easily. 
Dr Latorre (Response to whole question)
: 
 452. The assumption that N. Galligena  spores could be transferred to clean fruit should be 
considered as a hypothesis that needs to be probed.   To my knowledge, there is no scientific literature 
addressing this point.  Based on gene ral disease knowledge, it is an extremely unlikely event.  It is 
                                                     
 
55 (footnote original ) IRA pp. 124-125. 
56 (footnote original ) IRA p. 125. WT/DS367/11 
Page 86  
 
  difficult to accept and may be impossible to suppor t the probability values assigned to this step, 
1 x 10
-6 and 1x 10-4.  Therefore, this evaluation overestimates the risk at this point on non-objective 
and credible bases. 
Question 79 
Please comment on the finding in Australia's IRA, in  reference to N. Galligena  that "none of the 
processes in the packing house are likely to substan tially reduce infections".  Is this evaluation 
objective and credible on the basis of the available scientific evidence?  Is it based on respected and 
qualified scientific sources?  Does this evaluation fall within a range that could be considered 
legitimate according to the standards of the sci entific community and the methodology applied in the 
IRA?  If latently infected fruit were to develop visi ble rot symptoms in storage, is this something that 
could be detectable at the time of packing in New Ze aland, so as to allow removal of such fruit?  
(IRA, Part B, p. 126;  paras. 4.73-4.74 and 4.28 3-4.285 of New Zealand's FWS;  and paras. 568-577 
of Australia's FWS) 
 
Dr Deckers : 
 
453. This seems to be logic while most of the NG infec tions are latent and are situated internally in 
the core of the fruits or in the stalk or calyx end of  the infected fruits.  Infected fruits will be easier 
visible at the end of the storage period when  the rotting process makes them more visible. 
Dr Latorre : 
 
454. Although there is no relevant scientific evidence, it is acceptable to consider that no aspect of 
the process in the packing house re duces the number of latently infected fruits.  Once the fungus has 
penetrated mature fruits, the normal post-harvest management including brushing, waxing, sorting 
and grading, cold storage and even fungicide treatment s, will be unable to arrest the fungus inside the 
fruits.  Cold temperature would only be able to re tard symptom development by lowering the rate of 
fungal growth. 
455. Latently infected fruits cannot be detected at the time of packing in New Zealand.  However, 
symptoms may appear after several weeks of cold stor age.  If lots of mature asymptomatic fruits are 
kept for several weeks in cold storage in New Zeal and, it would be possible to remove infected fruits 
before export to Australia, lowering the risk of entrance. 
456. The likelihood that inocula contaminating the surface of the fruits can survive this process, 
attached to the fruit surface, is negligible or zero and it should be disregarded from the risk analysis. 
Dr Swinburne (Response to Questions 77, 78 and 79) : 
 457. The difficulty of analysing the reasoning behind Imp steps 3-7 is  that at each stage infection 
and contamination processes are conflated. 
458. Contamination:  any conidia deposited on the su rface of an apple during harvesting operations 
would not survive for any length of time (see Q 49) and may be discounted from all subsequent 
calculations.  Similar considerations would apply to conidia redistributed from trash.  There is, for example, no evidence to support assertions that such  as "spores would survive waxing" or "brushing", 
because these processes are irrelevant to the inherent inability of conidia to survive for long periods. 
459. Infection:  The European experience indicates,  in areas in which summer rainfall is frequent, 
fruit can become infected during the growing season.  Such infections, perhaps invisible at harvest, 
would not be affected by handling, or washing by wa ter, even with disinfectant present.  However, the 
store conditions and the duration of the holding period  will be a factor in any subsequent development  WT/DS367/11 
 Page 87 
 
 
  of any quiescent infections that may be present (Berrie, Xu & Johnson 2007 in appendix).  For 
example, if apples held in bulk bins are at a later time graded into retail ready packs those infections 
which have become visible rots will be removed (i rrespective of the causal organism).  Consequently 
there are pack house operations that could reduce the pr obability of the shipment of infected fruit. (see 
Q52).  Arguably, if any of the ro tted apples had produced conidia these could transfer to healthy fruit, 
but it is probable that these, as mere surface contamin ants, would not survive unless, after grading, the 
fruit was kept wet for several hours, which is co mmercially undesirable.  If a washing process was 
interposed in this final grading, disinfectant in the water would destroy any conidia thus displaced. 
460. The probabilities assigned in the IRA to these st eps are all difficult to reconcile with the 
observations above, especially as they all omit the factor of time.  (see Q80/81) 
Question 80 
Please comment on the likelihood values and distribution put forth by Australia's IRA for importation step 4 regarding N. Galligena surviving routin e processing procedures in the packing house (a 
triangular distribution between 0.7 and 1, with a most likely value of 0.8).  Is this evaluation objective and credible on the basis of the available scientific evidence?  Is it based on respected and qualified 
scientific sources?  Does this evaluation fall with in a range that could be considered legitimate 
according to the standards of the scientific comm unity and the methodology applied in the IRA?  
(IRA, Part B, pp. 125-126;  paras. 4.282 and 4.287 of New Zealand's FWS;  and paras. 564-580 of 
Australia's FWS) 
 
Dr Deckers
: 
 
461. Important point in this discussion is the timing of the preparation of the fruits for export:  is 
this done after a longer period of fruit storage, the ch ance that internal infections of NG develop into 
rotten fruits is greater and this will reduce the possi bility of introduction of the disease into Australia.  
When the fruit preparation is done after a shorter period of storage, the internal infections of NG will 
not show up and this will increase the risk for an introduction. 
Dr Latorre : 
 462. There is no scientific literature to support the assumption that the likelihood values for step 4 
vary between 0.7 and 1, with 0.8 as the most lik ely value.  This assumption, 80% likelihood that 
N. Galligena  will survive routine processing procedures in th e packing house, falls within a range that 
is difficult to legitimize, if this assumption implies that the inoculum must remain on the fruit surface.  
Rather, it would be possible for the inoculum  to be present internally in the fruit. 
Dr Sgrillo
: 
 463. The effect of the processing procedures in N.galligena  depends on whether the fruit is 
infested or infected, because the pathogen in inf ested fruits could be removed by washing while the 
pathogen in infected fruit could not. 
464. To correctly assess the survival of N.galligena  with transparency it would be necessary first to 
establish what proportion of fruit with the pathogen is expected to be infested
 and what proportion is 
expected to be infected .  Then, assign a probability distribution (and its parameters) to describe the 
survival in infested fruits and fi nally correct the parameters to d escribe the survival in any fruit. WT/DS367/11 
Page 88  
 
  465. However, considering the washing procedure,  IRA recognizes that:  "Although there is no 
specific data to indicate their effectiveness against N. Galligena , it is likely these chemicals used at 
the correct dosage rates (concentration and time) would have varying degrees of effectiveness."
57 
466. Considering that there is no factual evidence of a most probable value, the IRA Team does 
not explain why the triangular distribution was chosen instead of a uniform distribution. 
467. If there is no information on the proportion of infected fruits in relation to the proportion of 
infested fruits neither on the efficacy of washing to  remove pathogen from infested fruits, then there is 
no scientific evidence to support the choice of  the values used in the distribution. 
Question 81 
Please comment on the likelihood values and distribution put forth by Australia's IRA for importation 
step 5 (triangular distribution between 1 x 10E–5 and 1 x 10E–4, with a most likely value of 5 x 10E–
5) regarding clean fruit being c ontaminated by N. Galligena during processing in the packing house.  
Is this evaluation objective and credible on th e basis of the available scientific evidence? 
 
Dr Sgrillo : 
 
468. The discussion presented by IRA referring to step 5 supports the conclusion that the 
probability that a clean fruit is contaminat ed during processing is negligible.  The IRA58 Team 
concludes: 
"Given the extremely small likelihood of fruit being infested/infected with 
N. Galligena , the probability of surface s pores being present on fruit and 
contaminating the dump water is similarl y extremely small." and "The likelihood of 
clean fruit getting infected due to twigs at  this stage would be extremely low." 
469. However the values chosen do not reflect this conclusion.  These values shows that for each 
200,000,000 fruit passing through the packing hou se 10.000 could be contaminated by N. galligena  
and this could not be considered extremely low. 
470. There is no scientific support to justify th e values chosen for the parameters of the 
distribution. 
Is it based on respected and qualified scientific sources?  Does this evaluation fall within a range that 
could be considered legitimate according to the standards of the scientific community and the 
methodology applied in the IRA?  In answering th ese questions, please cons ider the IRA's assessment 
regarding the potential for clean apple fruit being c ontaminated by spores in the dump tank water.  
(IRA, Part B, pp. 126-127;  para. 4.288-4.292 of New Zealand's FWS;  and paras. 581-582 of 
Australia's FWS) 
 
Dr Sgrillo : 
 
471. The evaluation is fine, although the maximum, minimum and most probable value does not 
correctly express the likelihoods wh en the population is considered. 
                                                      
57 (footnote original ) IRA p. 125. 
58 (footnote original ) IRA p. 127.  WT/DS367/11 
 Page 89 
 
 
  Dr Deckers (Response to whole question) : 
 472. This risk seems to be very low because it s hould be infected by the spores present in the 
grading water. 
Dr Latorre (Response to whole question)
: 
 
473. There is no scientific literature to support the assumption that the rate of clean fruit 
contamination with N. Galligena  would vary between 10-4 and 10-5 (most likely value of 5 x 10-5) 
(importation step 5) in the packing house.  Ba sed on disease knowledge, it is extremely unlikely to 
occur under normal fruit management.  This should be disregarded from the risk analysis. 
Question 82 
Please comment on the likelihood value of 1 presente d in Australia's IRA regarding the probability 
that N. Galligena would survive palletisation, qua lity inspection, containerisation and transportation 
(importation step 6).  Is this evaluation objecti ve and credible on the basis of the available scientific 
evidence?  Is it based on respected and qualified scien tific sources?  Does this evaluation fall within a 
range that could be considered legitimate accordi ng to the standards of th e scientific community and 
the methodology applied in the IRA?  (IRA, Part B, p. 127;  paras. 4.293-4.295 of New Zealand's FWS;  and paras. 595-598 of Australia's FWS) 
 
Dr Deckers
: 
 
474. The same remark as on question 80 should be made here. 
Dr Latorre : 
 475. There is no scientific literature to support the assumption that N. Galligena  can survive 
palletisation, quality inspection, containerisation a nd transportation (Step 6).  Comments:  (i) It 
appears to be reasonable to assume that post-harvest  processing does not affect survival of latently 
infected fruits, and then a value of 1 could be acceptable only for the survival likelihood of the 
internal inocula.  (ii) However, these post-harv est processes can affect survival of the external 
inoculum, epiphytically contaminating the fruit surf ace, which may be negligible.  Then a value of 
1 would be unacceptable.  (iii) The Biggs (1995) article is not relevant; it does not deal with 
N. Galligena . 
Dr Sgrillo
: 
 476. IRA states that "Some infected fruit not detected during sorting may be identified at quality 
inspection."
59 
477. Therefore the parameters of the distribution s hould reflect the probabilit y of some infected 
fruits being detected in quality inspection.  The choi ce of the value 1 for the probability of survival of 
N. Galligena  means that infected fruits will never be det ected in the quality inspection.  This implies 
to accept that efficacy of sorting to detect infected  fruits is 100% and the efficacy of quality inspection 
is 0%. 
Question 83 
Please comment on the likelihood values and distri bution presented in importation step 7 of 
Australia's IRA regarding clean fru it being contaminated by N. Gal ligena during palletisation, quality 
inspection, containerisation and transportation (un iform distribution between 0 and 1 x 10E-6).  Is 
                                                      
59 (footnote original ) IRA p. 127. WT/DS367/11 
Page 90  
 
  this evaluation objective and credible on the basis of the available scientific evidence?  Is it based on 
respected and qualified scientific sources?  Does this  evaluation fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  (IRA, Part B, p. 128;  para.  4.296 of New Zealand's FWS;  and paras. 599-601 of 
Australia's FWS) 
 
Dr Deckers
: 
 478. This risk is extremely low when the fruits ar e prepared after a longer period of storage, 
because most of the fruits that have  internal infections of NG will be developed into rotten fruits and 
can be removed during preparation. 
Dr Latorre
: 
 479. There is no experimental evidence allowing us to  assume that the likelihood that packed clean 
fruit is contaminated with N. Galligena  would be different from zero, at Step 7.  Comments:  (i) At 
this stage it is unlikely that latently infected  fruits develop symptoms and less likely that N. Galligena  
sporulates on the surface of latently infected fruits.  (ii) Even if the inoculum (conidia) is present, 
post-harvest dissemination by fruit contact woul d be extremely unlikely because fruit injuries are 
needed for infection.  (iii).This evaluation (Step 7) falls within a range that could not be considered 
legitimate. I suggest discounting th is step from the risk analysis. 
Dr Sgrillo
: 
 
480. See responses 133 – 134. 
Dr Swinburne (Response to Questions 78, 80, 81, 82 and 83) : 
 481. The assignment of necessarily subjective probab ilities within a risk assessment model is not 
within the normal ambit of researchers whose stoc k in trade is data derived from experiments.  
Additionally, the importation steps described in th e model do not fit comfortably with the steps in 
commercial marketing, as practised in, say, the UK.  Consequently it is inappropriate to comment here 
on the veracity of the conclusions of each step  individually, but the overall model does need 
comment: 
482. It is usual for dessert apples to be harvested into  bulk bins that are transported to on-site CA 
(controlled atmosphere) stores, where they are cooled , and sealed in chambers with adjusted CO2 and 
O2 concentrations.  At intervals dictated by ma rketing strategies they are removed from these stores 
and dispatched to specialist pack  houses, where the operations of washing, grading and packed for 
retail.  The process may extend over many months, which has not been factored into the IRA model.  Any infections present may develop into rots during th is time, and this will be strongly influenced by 
both the store temperature and environment (Berrie et al 2007, appendix1).  At grading these would 
be removed, so the numbers of infected fruit will di minish with time, consequently the statement that 
"none of the pack house measures would reduce infec tion" is incorrect, as it must also embrace the 
CA store period. 
483. At several of the Imp steps the IRA emphasises the risk of superficial contamination but omits 
reference to any opportunities for these to convert to infections.  Curiously it also overlooked the 
possibility that an infected fruit  could develop into a rot with spores in store.  These could be 
redistributed in the wash water to healthy fruit if they were not removed beforehand.  This has not 
been found to be a problem in the UK, probably be cause of disinfectants in the wash water and the 
fact that apples are allowed to dry rapidly before packing.  WT/DS367/11 
 Page 91 
 
 
  484. The IRA model does show a reduction in the num ber of infected/contaminated fruit between 
harvest and dispatch, which in general would be exp ected, but how that was derived in the light of the 
observations above is not clear. 
Question 84 
Please comment on the conclusion in Australia's IRA regarding the probability  of importation of 
N. Galligena.  In particular, is the conclusion regarding a mean estimate for infection/infestation rate 
(0.0068% of the total proposed number of apples imported from New Zealand) objective and credible 
on the basis of the available scientific evidence?   Is it based on respected and qualified scientific 
sources?  Does this conclusion fall within a range that could be c onsidered legitimate according to 
the standards of the scientific community and the met hodology applied in the IRA?  (IRA, Part B, 
p. 128;  para. 4.299 of New Zealand's FWS;  and paras. 602-603 of Australia's FWS)  
Dr Deckers
: 
 485. The final infection rate of the fruits will str ongly depend on the presence of the NG infections 
in the orchards in New Zealand.  Maybe it should be good the take the differences in susceptibility of 
the different apple varieties for NG into account when making the final estimation. 
Dr Latorre
: 
 486. Considering that mature apple fruits are from areas where climate conditions are not 
particularly conducive for fruit infection, a mean infe ction/infestation rate of 0.0068% falls out of the 
range that could be considered legitimate on the basis of general knowledge regarding the European 
canker.  This value may not explain the real infec tion/infestation rate;  therefore, it needs to be 
validated before acceptance. 
Dr Sgrillo
: 
 
487. The proportion of 0.0068% of fruits infected  was generated by Monte Carlo simulations 
executed by the IRA Team.  Considering the importation volume expected by Australia60 this 
proportion would result in 3,400 to 27,200 infected fruits imported by year. 
488. The steps that compose the model are hypothesis about the real system.  If each of these 
hypotheses is evaluated and validated, the model w ould also be validated and it result could be 
accepted.  However the data presented in the IRA we re not considered sufficient to validate each of 
the hypotheses proposed because most of the values of the distributions were established by guesses 
and not by sampling of the real world. 
489. The result of a mathematical model is as good as the value assigned to its variables.  Many of 
the parameters used in the simulation were consid ered overestimated because they didn't reflect the 
meaning of the qualitative category in the population.  As consequence, the final result could also be 
overestimated. 
490. As IRA does not present real data to validate th e final result of the simulation is supposed that 
these data do not exist. 
Question 85 
Taking into account the quantitative data from th e literature cited by Australia's IRA regarding the 
inoculum dose necessary for an N. Galligena infec tion to occur, please comment on the conclusions 
contained in the IRA on the ultimate assignment of probability values for exposure.  Are those 
                                                      
60 (footnote original ) IRA p. 19. WT/DS367/11 
Page 92  
 
  conclusions objective and credible on the basis of th e available scientific evidence?  Are they based 
on respected and qualified scientific sources?  Do these c onclusions fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  (IRA, Part B, pp. 134-139;  para. 4.314 of New Zealand's FWS) 
 Dr Deckers
: 
 491. The success of an infection of NG is not only in oculum dependent , but will largely depend on 
the conditions under which the infection has to be r ealised and on the presence of an host plant in a 
susceptible stage at the moment the inoculum is high enough to realise an infection.  Question here is 
if there will be a host plant in a susceptible st age when a rotten fruits releases spores in the 
environment. 
Dr Latorre
: 
 492. The factors considered by Australia's IRA are a cceptable; however, it is difficult to judge the 
likelihood assigned to each parameter.  Although it is  described in AUS-2BA (p. 136), it is not clear 
how Australia's IRA relates the inoculum dose neces sary for infection and the probability of exposure 
to susceptible host plants. 
Dr Sgrillo
: 
 493. The quantitative data regarding the inoculum dose necessary for an N. Galligena  infection to 
occur, cited by IRA, were not used by the IRA Team, at least in a direct way. 
494. The minimum and maximum parame ters elected for the Exposure are not directly derived 
from the source data.  The IRA states:  "These valu es [exposure] are based on the IRA team's view 
taking into account all the factors discussed above."
61  However the IRA Team does not explain how 
the available data were used. 
495. The considerations of response 36 also apply to N.galligena.  
496. The estimated likelihood of the exposure of N.galligena  to susceptible host plant varies from 
"negligible" to "extremely low".62  However when the values assigne d to these categories are analyzed 
together with the total population (150.000.000 of fruits) the numbers that come out, in the lower 
categories, are much above than the qualitative desc ription of the categories.  See also responses 133-
134. 
Dr Swinburne (Response to Questions 84 and 85) : 
 497. The end point of this analysis, predicting th at 0.0068% of apples imported will "carry" the 
disease is predicated on a starting point presumption of a probability that each picked fruit is infected 
between 10x E-6 & 10xE-3, which at best is far too la rge to be credible.  (see Q75).  Given all the 
uncertainty in the calculations fo r the intermediate steps (see Q78-83) this outcome does not inspire 
confidence. 
498. In theory one spore can initiate infection;  in practice the probability of successful infection 
with one spore is very small.  Th e literature cited in the IRA (p136) all indicate that the probability of 
securing infection increases with dose, and that at approximately 1000 spores per fresh leaf scar almost 100% infection will occur.  More recent data  (Lolas, 1999, Ph.D. thesis University of London) 
                                                     
 
61 (footnote original ) IRA p. 138. 
62 (footnote original ) IRA p. 139.  WT/DS367/11 
 Page 93 
 
 
  also demonstrates that the number of conidia needed  to achieve 50% infection varies with cultivar;  
another factor. 
499. The "exposure value" quoted, assuming it is credible  to deduce such a factor, seems to make 
assumptions regarding the year-round availability of in fection sites, and that all discarded apples 
discharge spores all year, which are not correct.  Moreover by stating " a significant exposure factor 
for N. galligena is the fact that the fungus has a specific  mechanism for spore dispersal " in the 
conclusion on p 138, suggests that the outcome wa s heavily reliant on the erroneous presumption that 
rotted fruit would release ascospores.  Unless the m eaning of these values has been misunderstood, 
and based on the import of 2X10E8 apples of which 0.0068% is infected, the worst case scenario is 
that c14 infection events/year are anticipated, or at the lower probability, it would take nearly 100 
years to get one such event. 
Question 86 
Please comment on the consequences assessment of "E" contained in Australia's IRA regarding the 
direct impact of European canker on plant life or he alth.  Is that assessment objective and credible on 
the basis of the available scientific  evidence?  (IRA, Part B, pp. 145-147;  paras . 4.326-4.327 of 
New Zealand's FWS;  paras. 676-686 of Australia's FWS)  
Dr Deckers
: 
 500. The impact of an infection on plant life or hea lth can indeed have substantial consequences 
for some regions in Australia.  A rainfall of 1000 mm alone is not enough to estimate the risk of one 
region; more important are the rainfall conditions  during specific periods of the growing season like 
during the leaf fall period or during harvest period when there are a lot of natural infection wounds 
available on the trees. 
Dr Latorre
: 
 
501. According to the definition provided by Australia's IRA (AUS-2 p. 38-39, Table 10), the 
impact score, "E", contained in Australia's IRA impl ies measurable (permanent or reversible) effects 
on the economy at national, regional, district an d local levels.  Specifically, it implies highly 
significant impact at district ("A geographically or  geopolitically associated collection of aggregates–
generally a recognized section of a state…") and local levels ("An aggregate of households or 
enterprises–e.g., a rural community, a town or a lo cal government area").  A "highly significant" 
impact would threaten economic viability through a la rge increase in mortality/morbidity, or a large 
decrease in production. 
502. Based on the knowledge of European canker, and according to the general experience 
observed in other apple exporting countries where European canker is present, considering the 
consequences impact as "E" is not credible particularly because: 
(a) Its economical effects (increased costs of  winter pruning, fungicide treatments and 
the removal of stem lesions and infected branches; fruit yield reduction) can be absorbed by farmers with no major conseque nces to the farmer or to the local apple 
industry. 
(b) The economical effects can be reversible rather than permanent at local levels. 
(c) Disease severity can be high at tree leve l but disease prevalence and disease incidence 
are commonly far less than 100%. WT/DS367/11 
Page 94  
 
  (d) Even under highly-prone environmental conditions, disease progress rate would be 
low rather than high.  Therefore, it would be very unlikely that N. Galligena  could 
attack a high proportion of the apple population in a single growing season at local levels. 
(e) Although European canker is often classifi ed as one of the most economically 
damaging diseases of apple, this is a relative concept, indicating that European canker 
is a major disease of apple.  In many apple-producing areas, this means that it requires adequate control measures annually.  However, it cannot be interpreted as 
being a devastating disease limiting apple pr oduction at districts or local levels. 
(f) "Fruit rot generally develops in the field or before harvest, although storage losses of 
10–60% of the stored fruit crop have been reported in various parts of the world 
(Swinburne, 1964; Swinburne, 1975)."  This may be true in some years and only under highly favourable environmental conditi ons at harvest.  On the basis of the 
climate analysis presented, weather in Australia is favourable but not highly favourable for disease development (fruit infection phase) in summer months. 
(g) There are no published records indicating that  losses due to European canker affect 
apple production to the extent that they can threaten the economic viability of the 
apple industry locally or nationwide. 
503. Therefore, the "E" score is unreal because it is un likely that losses can be severe at the district 
or local level. 
Question 87 
Please comment on the consequences assessment cont ained in Australia's IRA regarding the control 
or eradication of European canker.  Is that assessment objective and credible on the basis of the 
available scientific evidence?  What is your view  on the relevance of New Zealand's assertion in this 
regard that, in case of an outbreak of European ca nker, routine orchard control of the disease is 
possible as part of routine controls of other appl e diseases already present in Australia, such as apple 
scab?  (IRA, Part B, p.148;  para. 4.331 of New Ze aland's FWS;  paras. 696-702 of Australia's FWS) 
 
Dr Deckers
: 
 504. When NG infections would occur in Austra lia, it would be necessary to consider a 
combination of specific fungicide treatments in co mbination with eradication measures at orchard 
level . It will be much more than the routine cont rols made for other diseases like apple scab.  Also 
the timing of some specific treatments during leaf fall period will be necessary. 
Dr Latorre
: 
 505. A rating of "D" was assigned to control or er adicate European canker, which implies that 
European canker is unlikely to be discernible at a na tional level and would be of minor significance at 
the regional level, but would be significant at the district level and highly significant locally.  This rating appears to be too high consider ing:  (i). Control of European canker would be unlikely to be too 
high, physically and economically  (ii). Contro l strategies for other apple diseases (e.g., apple scab, 
powdery mildew) would help to control European canker.  (iii). The rate of disease progress is commonly low, which implies that eventual out breaks of European canker must be localized, 
facilitating control and eradication.  (iv) The presence  of European canker has no effect on apple trade 
internationally, except with Australia.  Thus, er adication of eventual European canker outbreaks 
would not affect the international trade.  WT/DS367/11 
 Page 95 
 
 
  Question 88 
Please comment on the findings cont ained in Australia's IRA that bi rds and insects are suspected to 
act as dispersal mechanisms of N. Galligena because birds may be able to transfer spores of infected 
fruit to a host by feeding on fruit discarded as wa ste and then flying on to branches of trees.  Are 
those findings objective and credible on the basis of the available scientific evidence?  Are they based 
on respected and qualified scientific sources?  Do these c onclusions fall within a range that could be 
considered legitimate according to the standards  of the scientific community and the methodology 
applied in the IRA?  (IRA, Part B, pp. 135-136;  par a. 615 of Australia's FWS;  para. 45 of the United 
States' Third Party submission) 
 Dr Deckers
: 
 506. This way of infection has not been proven scien tifically.  Whenever birds or insects would be 
a vector for a NG spores, there would be also a n eed for a wound or a fresh leaf scar on the branch 
before the NG infection can take place. 
Dr Latorre
: 
 507. There is no scientific evidence demonstra ting that birds and insects can disperse N. Galligena .  
These considerations are not acceptable and would not be legitimate according to the standards of the 
scientific community. 
Dr Swinburne
: 
 
508. There is no scientific evidence that birds or other vectors are involved in the dissemination of 
infective agents of N. Galligena . 
Question 89 
Please comment on whether the consideration in Aust ralia's IRA of the risk associated with the 
practice of packing houses leaving orchard wholesa ler waste uncovered and exposed to the elements 
on the premises or in landfills is objective and credible , taking into account the likelihood of this 
situation occurring in packing houses in Australia.  (IRA, Part B, p. 130 (European canker);  
paras. 4.130 and 4.419-4.421 of New Zealand's FW S;  paras. 784-785 and 898-900 of Australia's 
FWS;  and R 100 by Australia) 
 Dr Deckers
: 
 509. Leaving high amounts of fruit waste in the ne ighbourhood of orchards should always be 
considered as a risk and should be avoided anyw ay.  The treatment of the fruit waste should be 
included in the standard operation procedures of each packing house. 
Dr Latorre
: 
 510. This possibility would be extremely unlikely cons idering that:  (i) Removal of fruit waste is 
essential to preventing infestation with other pests.  (ii) Removal of fruit wastes is needed to comply 
with good agricultural practices.  (iii) Dropping in fected fruits or leaving wastes uncovered on the 
ground runs against the standards of packing hou ses and against the cultural attitude of Australian 
people.  This possibility should be disregarded from the risk analysis. 
Dr Swinburne
: 
 511. There are several factors that mitigate against the possibility that dumped infected fruit pose a 
hazard to nearby orchards.  Firstly, such a dump w ould have to be extremely close to potential host WT/DS367/11 
Page 96  
 
  trees, as the conidia are unlikely to  be splashed dispersed more than a few meters, vertically or 
horizontally (seeQ73).  Secondly, this has to occur not only during rain, but when the host is receptive 
to infection, which in commercial practice would be in spring at bud burst;  consequently all the fruit 
discarded during the winter would have to remain in situ  until then, which is unlikely in normal 
commercial practice. 
512. In the UK fruit is picked and then stored in CA  facilities on farm, but then sent to specialised 
pack houses with grading facilities.  These are genera lly located in industrial parks, often close to 
other wholesale distribution centres.  These sites are usually devoid of any amenity planting, and remote from orchards.  If comparable practices ar e followed in Australia, it seems unlikely that fruit 
discarded at pack houses poses any great risk. 
Question 90 
Please comment on the reasoning contained in Australia 's IRA in relation to the Tasmanian outbreak.  
Is that reasoning objective and coherent? In par ticular, please comment on the relevance of the 
fungus having no asci or ascospores, and wheth er the latter are better suited to long distance 
dispersal than conidia.  Please al so comment whether it is possibl e that the Tasmanian outbreak may 
have been due to a unique strain of N. Gallige na that required another mating type for reproduction 
and whether this could explain why there was a limited spread of the disease during the Tasmanian 
outbreak.  Please comment on whether climate is a relevant factor and whether the local climatic 
conditions during the relevant time period in Sp reyton, Tasmania, may have been unfavourable to 
that particular strain of the disease.  Please also  comment on whether the chemicals used to control 
apple scab could have had an impact on the limited spread of N. Galligena during the Tasmanian 
outbreak.  (IRA, Part B, pp. 117-118, 141-149;  paras. 4.86, 4.92-4.93, 4.415-4.416, 4.323-4.324 of 
New Zealand's FWS and pp. 224-225 of Annex 3 to  New Zealand's FWS;  paras. 632, 654-669, 691 
and 890-892 of Australia's FWS;  and R 73 by New Zealand, para. 160) 
 
Dr Deckers
: 
 
513. Different factors are probably involved in the limited spread of the NG infection in Spreyton 
in Tasmania:  the combination of strict eradicati on measures and of specific fungicide treatments will 
have limited the further spread to other regions .  Probably the climatological conditions were not 
optimal for a strong disease development.  The hypo thesis of the presence of a unique strain seems 
unlikely to me.  The introduction could have been here trough infected plant material.  The lack of 
ascospores can be the consequence of the fact that there was no formation of  the perithecia in which 
the ascospores can be formed. 
Dr Latorre : 
 514. The reasoning contained in Australia's IRA in  relation to the Tasmanian outbreak seems 
reasonable.  Comments: 
(a) One would expect slow movement if envi ronmental conditions for establishment and 
spread of European canker are rather unfavourable. 
(b) The absence of ascospores is irrelevant, cons idering that in most parts of the apple-
producing areas, European canker is successfully disseminated by conidia. 
(c) It is true that ascospores can be moved by wind currents facilitating dispersal.  
Nevertheless, I doubt that the absence of ascospores limits the spread of European 
canker under Tasmanian conditions .  It is possible that the environmental conditions 
in Tasmania were unfavourable for ascospore production.  WT/DS367/11 
 Page 97 
 
 
  (d) Unfavourable climatic conditions and the use of chemicals to control apple scab, or 
even specific fungicide treatments to control N. Galligena , may have limited disease 
spread in Tasmania. 
(e) Ascospores and conidia can be dispersed locally (meters from the source of the 
inoculum).  Long-distance dissemination (kilometres) is explained by the 
transportation of infected plants. 
Dr Swinburne : 
 515. The outbreak of canker at Spreyton, Tasmania is used by both sides to support opposing 
views of the likely hood of the disease establishing on mainland Australia. 
516. There seems to be acceptance that this outbreak  originated in nursery infection (seeQ53) prior 
to the trees being planted, which is consistent with the report that it was confined to a few blocks or 
orchards on some farms.  Failure to spread beyond this limited area is attributed by the parties to 
conflicting reasons: 
517. The Australian position is that spread did not o ccur due to a combination of the eradication 
programme, fungicide regimes used to control scab and the possibility that this outbreak was caused 
by an aberrant strain of the pathogen that l acked the ability to produ ce the ascospores necessary for 
long distance dispersal.  The removal of all infect ed trees would reduce and finally eliminate the 
opportunity to spread but does not explain the failure to do so in the earlier years.  There is no doubt that fungicide regimes for scab do reduce the sever ity of canker incidence (seeQ53) but would not 
explain the failure of existing cankers to form perith ecia.  There is no evidence in the literature that 
there are distinct strains of the pathogen responsible  for European canker in the apple, including the 
data of Flack & Swinburne (1975).  The alternative explanation put forward for the lack of ascospores 
is that the pathogen is heterothallic, and one of the mating types was missing.  There are conflicting 
reports in the literature c oncerning sexual reproduction in Nectria  (El-Gholl, Barnard & Schroeder 
1986; Kruger, 1974), but the former (homothallic) seems the most convincing.  To assume that failure 
to form mature perithecia was due to the presence of only one mating type also requires the 
assumption that the entire epidemic originated, somewh ere, with one spore, which is most unlikely. 
518. The NZ position is that climatic conditions in Tasmania are marginal for the development of 
canker, and this accounts for the failure of the disease to spread.  The impact of climate generally is 
discussed in Q56.  In California ascospores fail to develop in most seasons, (Wilson, 1966).  That this 
is due simply to climate and not to problems i nvolving heterothallism or unusual strains of the 
pathogen is revealed by observing that in some years they do develop in California. 
519. Australia additionally invokes the Tasmanian experience as evidence that the disease can 
establish elsewhere on the mainland, and cites the di fficulties of eradication there as a guide to the 
economic impact that would result if it did so.  The weakness of any predictive model based solely on 
annual rainfall has already been discussed (Q66).  The ke y factor has to be related to the days of rain-
fall, (leaf-wetness duration), associated with spore formation, dissemination and finally infection.  
The Beresford and Kim model (Annex 3 NZ FWS), whic h crucially includes rain days, predicts that 
Tasmanian districts have a climate which is only ma rginally congenial for canker, thus explaining the 
duration of the outbreak. 
Question 91 
Does Australia's IRA provide an objective and coheren t assessment of the likelihood and implications 
of New Zealand apples being repacked at rural packi ng houses in close proximity to orchards, when 
assessing the risks related to fire blight, European  canker and ALCM?  Was such assessment made 
with proper methodological rigour?  (Para. 4.418 of New Zealand's FWS;  R 99 by Australia) WT/DS367/11 
Page 98  
 
   
Dr Deckers
: 
 520. I don't see the necessity to repack fruits that are exported from New Zealand to Australia. 
Dr Latorre
: 
 
521. The assessment and implication of the repacked  apples at rural packing houses in close 
proximity to the orchards is a possibility that cannot  be denied.  However, the impact of repacked 
fruits can be minimized if fruit is exported in retail-ready packs, as Ne w Zealand has suggested. 
Dr Sgrillo : 
 
522. See question 46. 
Dr Swinburne : 
 523. Fruit shipped from New Zealand in bulk bins to  pack houses in Australia for final grading 
could have had time to develop ro ts, including, if present, time for quiescent infections by Nectria to 
become progressive.  Fruit graded in NZ into retail ready packs need only to go  to distribution centres, 
and, as any rots will have already been removed,  have only a relatively short time to develop any 
more.  (Q53).  The removal of any rots during grading in NZ would in any event reduce the number arriving in Australia; this does not seem to have been allowed for in Step 6 (IRA p127)  (see Q82). 
524. It is not possible to comment on the marketing strategies that might be adopted.  But R99 by 
Australia makes it clear that the IRA indicates that fruit discarded by consumers constitutes the 
greatest threat for the disease to enter the country.  Fruit out of store would be held at considerably 
less than 100%RH.  To become infectious units, discarded apples would require a period of "leaf 
wetness" to develop spores.  It is most unlikely that in the prevailing climate all rotted apples so 
discarded would become infectious units. 
Question 92 
Is the requirement identified in Australia's IRA that a packing house provide details of the layout of 
the premises, sufficiently justified by the scientific evidence relied upon?  (IRA,  Part B, pp. 317;  
para. 4.149 of, and pp. 242 and 247 of Annex 4 to, Ne w Zealand's FWS;  and para. 963 of Australia's 
FWS) 
 Dr Deckers
: 
 525. It is not clear which risk Australia wants to reduce with this measure. 
Dr Latorre
: 
 
526. The general rules that registered packing houses must comply with normal procedures in 
accordance with good agricultural pr actices is acceptable.  However, there is no risk of fruit 
contamination at packing houses unless infected fruits with visible sporulation are processed along with healthy fruits, but this possibility is neglig ible and in practice it should be regarded as non-
existent.  At present, there are no scientific reports  demonstrating the spread of European canker at 
packing houses.  WT/DS367/11 
 Page 99 
 
 
  Dr Swinburne : 
 527. The requirement to provide details of pack house layout seems out of all proportion to the 
minute risk posed by any threat of cross contam ination of apples supposedly coming from infected 
orchards.  The inability of superficial conidia to  survive on the surface of fruit has already been 
discussed.  (Q49 etc).  The same applies to any that  might be transferred on boxes, grading machines 
or any other piece of equipment. 
Question 93 
Please comment on whether, from a technical persp ective and as described in Australia's IRA, the 17 
specific measures that have been challenged by New Zealand can be distinguished  as either measures 
active in risk reduction, or measures designed to im plement or support active measures.  (R 14-26 by 
the Parties) 
 
Dr Deckers
: 
 
528. All measures have the intention to reduce the inf ection risk actively, directly or indirectly. 
Dr Latorre : 
 
 
Measures challenged by New Zealand 
Nº Description Active in 
risk reduction To implement 
or support active measures 
Fire blight 
1 The requirement that apples be sourced from areas free from 
fire blight disease symptoms. Yes  
2 The requirement that orchards /blocks be inspected for fire 
blight disease symptoms…  Yes 
3 The requirement that an orchard/block inspection 
methodology be developed and approved that addresses issues such as visibility of symptoms in the tops of trees ,…  Yes 
4 The requirement that an orchard/block be suspended for the 
season on the basis that any evidence of pruning …  Yes 
5 The requirement that an orchard/block be suspended for the 
season on the basis of detection of any visual symptoms of 
fire blight.  Yes 
6 The requirement that apples be subject to disinfection 
treatment in the packing house. Yes  
7 The requirement that all grading and packing equipment that 
comes in direct contact with apples be cleaned and 
disinfected (using an approved disinfectant) immediately before each Australian packing run. Yes  
8 The requirement that packing houses registered for export of 
apples process only fruit sourced from registered orchards.  Yes 
European canker 
9 The requirement that apples be sourced from export 
orchards/blocks free of Eur opean canker (pest-free places of 
production). Yes  
10 The requirement that all trees in export orchards/blocks be 
inspected for symptoms of European canker,…  Yes WT/DS367/11 
Page 100  
 
  11 The requirement that all new planting stock be intensively 
examined and treated for European canker Yes*  
12 The requirement that an orchard/block be suspended for the 
season on the basis that any evidence of pruning or other activities carried out before the inspection could constitute an attempt to remove or hide symptoms of European canker.  Yes 
13 The requirement that exports from an orchard/block be 
suspended for the coming season on the basis of detection of 
European canker and …  Yes 
Apple leafcurling midge, ALCM 
14 The requirements of inspection and treatment for apple 
leafcurling midge,… Yes  
General 
15 The requirement that Australian Quarantine and Inspection 
Service officers be involved in orchard inspections for 
European canker and fire blight, in direct verification of 
packing house procedures, and in fruit inspection and treatment.  Yes 
16 The requirement that New Zealand ensure that all orchards 
registered for export to Australia operate under standard commercial practices.  Yes 
17 The requirement that packing houses provide details of the 
layout of premises.  Yes** 
 
*To my understanding, this measure would prevent further dispersal of European canker; however, it does not 
directly reduce the risk of fruit contamination. I suggest eliminating this measure. 
**To my understanding, this measure does not apply, considering that there is no scientific evidence supporting 
the possibility that European canker can be disseminated at the packing houses. 
 
Dr Swinburne : 
 
529. The following measures would be deemed to be  in support of active measures, and not active 
measures in risk reduction:  planting healthy stock as replacement trees, disqualification of an orchard 
if pruning began before inspection, requirement of pack house layout, and indeed the direct 
involvement of AQIS officers in the inspection processes. 
IV. ALCM 
Question 94 
Please comment on whether the evaluation in Austra lia's IRA of the following issues was objective 
and credible, relying on respected and qualified scientific  sources, and based on sufficient support in 
the available scientific evidence:  (i) the conditions  for adult emergence of ALCM;  (ii) the number of 
ALCM generations per year;  (iii) the flight range of  ALCM;  (iv) the adult life span of ALCM;  (v) the 
climatic factors in respect of ALCM spread;  (v i) the host range and c onditions required for ALCM 
egg laying;  (vii) the absence for the need for a vect or for ALCM to be able to spread from its initial 
location;  and (viii) the life stage in which ALCM could enter Australia on export apples imported 
from New Zealand.  (Paras. 85, 743-745, 796-797 and 802-815 of Australia's FWS;  R 81 and 85 by 
New Zealand) 
  WT/DS367/11 
 Page 101 
 
 
  Dr Cross : 
 
(i) the conditions for adult emergence of ALCM 
 
530. There is a disagreement between the parties as to the time that would be needed for ALCM 
adults to emerge after being removed from cold storage.  NZ claims that 13-18 days would be 
required but supply no evidence to verify this.  Fo r such a narrow time window of emergence, all 
individuals would have to be at the same stage of development (pre-diapause mature 3rd instar larvae) 
at harvest, be forced into diapause by a possibly s hort period of cold exposure, be held in a long 
enough period of cold exposure to break diapause in a ll individuals and then be raised to a constant 
high temperature (> 25 °C) until emergence occurred .  Even if this happened it is unlikely that 
emergence would occur over a period of 5 days.  Ne w Zealand's claim must be based on a supposition 
that all pupae and individuals at other stages of deve lopment are killed by cold storage, even if the 
cold exposure were for short periods.  This is pr obably not the case and evidence needs to be provided 
by New Zealand before the 13-18 days emergence dela y for all individuals should be considered true. 
531. Australia is probably correct to assert that (some) adults could emerge as soon as the 
appropriate triggers are encountered by the pupa.  It  is likely that individuals would emerge over quite 
an extended period ranging from <1 day to > 60 days and possibly to > 1 year depending on 
conditions.  In many midge species, a proportion of i ndividuals need two or more "winter" periods of 
cold to break diapause.  However, no studies a ppear to have been done to resolve the issue 
definitively for ALCM. 
532. It is likely that ALCM in cocoons on apple fruits emerging from cold storage would be at a 
wide range of stages of development including: 
1. Third instar larvae that have just cocoone d and need to complete diapause and post 
diapause development.  Note the word "pre -pupa" is sometimes used to refer to the 
mature third instar larva in a cocoon befo re it pupates.  Whilst this is perhaps a 
convenient label it is meaningless in the case of ALCM.  There is not a fourth instar 
that might be recognised as a pre-pupal stad ium, as in some other insects.  Darvas, 
Skuhrava & Andersen (2000), in "Agricultural Dipteran Pests of the Palaearctic Region" record that prepupae of the th ird generation overwinter in cocoons and 
pupate in the spring and give Alford ( 1984) as one of their references for that 
statement.  But Alford (1984) does not mention prepupae.  Gagne, in his major works 
on North American and Neotropical gall midges (Gagne 1989, 1994) makes no 
mention of prepupae.  In any case, these individuals would require a period of exposure to cold to break 
diapause followed by a period of post diapause development to adult emergence 
which would vary considerably according to temperature.  The time requirements for 
development and how they vary with temper ature for these individuals have not been 
determined for ALCM.  Note that the emergence of first generation ALCM males in spring can occur over a period of several weeks (Tomkins et al., 2006 (Aus exhibit 92)), a considerably greater time span th an the 5 day range between 13 and 18 days 
indicated by NZ.  In any case, the time requirements for these individuals could be 
greater than the requirements for individuals in 2 below. 
 
2. Mature third instar larvae that have ju st cocooned that do not require diapause but 
have to complete pupal development.  Peri ods of cold may force all these individuals 
into diapause but this has not been prov en and the conditions (exposure times/cold 
severities) to force pre-pupae into diapau se have not been studied and are thus 
unknown.  It is quite possible that some matu re third instar larvae in cocoons in cold WT/DS367/11 
Page 102  
 
  store would not go into diapause if cold exposure time were short.  Barnes (1948) 
reports that pupal development takes 13-18 da ys but this was an approximate time 
range for individuals held at ambient conditi ons in a laboratory.  The rate of insect 
development is usually proportional to temp erature above a threshold temperature.  
Unfortunately, the threshold temperature and the day degree requirement for ALCM 
have not been determined, though some information on which to calculate them is 
provided by Shaw et al. (2005) (NZ exhib it 16).  Using development times to 50% 
emergence of 61, 35, 23, 19 and 14 days at 11, 15, 19 23 and 27 °C, respectively (taken from figure 2 on page 309) and performing liner regression between the rate of development against temperature, an exce llent linear fit is obtained (R2=0.991) 
giving a threshold development temperat ure of 6.44°C and a requirement of 295 
degree-days above the threshold temperatur e for 50% emergence.  If temperatures are 
only just above the developmental threshold of 6.44 °C when the ALCM on apples were removed from cold store, pupal deve lopment could take a long time, perhaps 
many weeks  If temperatures were high, development would proceed rapidly and 
emergence could perhaps occur in less th an 13 days, though it is probable that 
prolonged exposure to high temperatur es would result in high mortality and 
development times much shorter than 13 days may be impossible.  Note that Shaw et 
al. (2005) (NZ Exhibit 16) only explore temp eratures in the range 11-12 °C and do 
not provide the time distributions of emergence.  
3. Pupae at various stages of development incl uding some at late stages of development 
that were nearly ready to emerge as adults at the moment of putting into cold storage.  
These individuals would be ready to emerge more or less as soon as suitable conditions for emergence were restored. 
 
NZ assertions seem to be based on an assump tion that cold storage of apples would 
either kill individuals that were pupating or  perhaps force them into diapause, though 
no evidence to support this has been supp lied.  Indeed, if pupae were killed by 
exposure to cold, then ALCM's existence w ould be threatened by post diapause cold 
periods in spring.  No evidence has been produced that AA or CA storage with very low oxygen conditions (< 1%) lead to rapid mortality of ALCM pre-pupae or pupae.  
Respiration rates of these life stages would be  very low and it's likely that individuals 
could survive long periods in CA. Gagne in his major works on North American and Neotropical gall midges Gagne (1989, 1994) says that pupal diapause, though known in the Cecidomyiidae, is rare, having been recorded in Contarinia negundinis  in North America, in Resseliella 
lavandulae  in France and in Hasegawia sasacola  in Japan.  It is most unlikely to 
occur in Dasineura mali . 
 What is lacking is good quality studies inves tigating  1) the eff ect of temperature on 
the rate of development (duration) of the different life stages of ALCM  2) requirements for diapause induction and breaki ng in ALCM  3) the effect of exposure 
to varying degrees of cold and CA storage on survival of the different ALCM life 
stages  4) The requirements for temperature, humidity and windspeed for emergence of adults after pupation.  Until such studies are done this question cannot be resolved 
with certainty.  
Unless evidence to the contrary  is produced, Australia's IRA relating to this issue was 
objective and credible and relied on limited sci entific evidence available.  However, 
an important point is that longer period of adult emergence would substantially 
reduce the likelihood of small numbers of  individuals in a consignment emerging 
within a few days of each othe r and being to mate and lay eggs to start an infestation.  WT/DS367/11 
 Page 103 
 
 
   
(ii) the number of ALCM generations per year  
 
533. Para 3.75 of NZ FWS that there are usually f our generations in NZ per annum though 5 have 
been reported ignores the report of up to 7 gene rations par annum in NZ by Tomkins (1998)( Aus 
exhibit 89).  However, the occurrence of 7 gene rations seems unlikely and would require a long 
season of continuously warm conditions with no interruptions by dry periods and continuous 
availability of growing shoots for galling.  To mkins (1998) may have based his estimate of 7 
generations on a simple calculation of the length of the season and the absolute minimum generation 
time of ALCM, rather than observing successive life cycles of the pest through the season, which 
would be very difficult.  The occurrence of 4 or exce ptionally 5 generations is more likely. Note that 
in Cross, Hall, Shaw and Anfora, Crop Prot ection 28(2009), 128-133, data, including from New 
Zealand, shows generation times of 52, 46 and 39 days  for the first 3 generation of ALCM between 41 
and 51 ° latitude.  However, the precise number of generations has only limited bearing on the risk 
assessment. 
(iii) the flight range of ALCM  
 
534. There don't appear to have been any studies in to the flight range of ALCM females where 
females are forced to find a hos t.  The distance in Aus IRA of 200 m is perhaps plausible but not 
supported by evidence.  The 30 m distance (over 3 generations) given in Suckling et al (2007) (NZ 
exhibit 15) is based on the decline in shoot infest ation rates in new apple trees adjacent to an old 
established planting in a sex pheromone mating disrup tion trial, a situation which is not directly 
analogous to the situation required for the risk assess ment of a mated female flying to a distant host.  
It does not indicate that females are only able to fly a maximum of 30 m.  The value of 200 m suggested by Australia appears to be based on the background rate of infestation up to 200 m shown 
in Figure 4 of Suckling et al. (2007) but this data does not show that these infestations were caused by 
longer range movement of females from the adjacent block.  Suckling et al. (2007) suggest that low 
levels of infestation were present on the new trees wh en they were planted.  Cross (pers. comm. 2005) 
(now published in Table 5 of Cross & Hall, Cr op Protection 28 (2009), 139-144) found that male 
ALCM could be attracted over a distance of 50 m (the greatest distance investigated) away from the host plant by a sex pheromone lure.  It is possibly that  the flight range of females is shorter than males 
because females are carrying an egg burden.  However,  females tend to have slightly larger, perhaps 
stronger bodies and wings which might compensate for this.  The flight range of females relative to 
males has not been investigated.  It is possible that  gusts of wind could increase the range flight range 
of females and this would seem logical though ther e appears to be no evidence to support this.  
ALCM avoids flying in windy conditions.  However, the example of the lettuce aphid invasion of Tasmania from NZ (2600 km) is not relevant as a phids are known to have long range dispersal 
mechanisms whereas leaf midges do not.  However, the assertion (Aus WS para 808) of a flight range 
of 30-50 m would be ample in many cases between an  orchard and pack house co-located within an 
apple orchard is reasonable. 
535. Australia's IRA with respect to  this issue was objective and plausible and relied on what little 
real evidence there was, but the available evid ence was insufficient for a scientifically sound 
assessment. 
(iv) the adult life span of ALCM  
 
536. The life span of females in the field will depe nd very much on microclim atic conditions at the 
time.  The life span of 2-6 days appears to be based on cursory laboratory observations and not on a 
properly conducted study of the distributions of longevity of males and females and how they are 
affected by conditions.  The meaning of the terminolog y "life span of 2-6 days" is vague.  It is unclear 
whether it means that the average life span is somewhere between 2 and 6 days or whether it means WT/DS367/11 
Page 104  
 
  all or at least most individuals live between 2 and 6 days.  The lower limit of 2 days does not include 
the probability that many individuals in some circ umstances will die on the day of their emergence.  
The life span of males and females is likely to be short in warm, dry, windy conditions.  Hall & Cross 
(2006) in the process of rearing many hundreds of vi rgin male and female ALCM adults to identify 
the midges sex pheromone, found that females held in glass entrainment vessels at 18-20 °C and low 
(<500 ml/min) airflow conditions mostly survived  < 1 day with a small number of individuals 
surviving for 2 days and none for longer.  Males he ld in the same conditions survived < 24 hours.  
Females held in small tubes with moisture provi ded in fridge conditions ~ 4°C survived 4-5 days, 
rarely 6.  Again, quantitative field studies are lacking but a life span of 1-2 days in the field is probable.  Males probably have a shorter life span than females.  However, there appears to be no 
substantive disagreement between the parties on th is issue even though in my view it has very 
substantial bearing on the risks of establishment and spread. 
537. The Aus FWS was objective and credible and used the available scientific evidence. 
(v) the climatic factors in respect of ALCM spread  
 538. In its assessment of the likelihood of spread  of ALCM in Australia, Australia's IRA 
considered the spread and distribution of ALCM throughout NZ since 1950.  Victoria, Tasmania and 
New South Wales were considered to have a suitabl e cool climate for the spread of ALCM but the 
assessment was broadly qualitative, not quantitative.  ALCM can tole rate quite a wide range of 
climates and it is inevitable that conditions conduciv e to ALCM establishment and spread are present 
in several, perhaps many areas of Australia, especia lly in areas where the climate is favourable to 
apple growing.  A weakness in the IRA is that Aust ralia failed to quantify (or at least delimit) the 
geographic range and range of c onditions which are necessary fo r establishment and spread of 
ALCM, both in terms of temperature and rainfall a nd their seasonal occurrence.  The geographic and 
climatic limits were not established. 
539. In the northern hemisphere, in the continent of Europe, where ALCM has long been present 
and has reached it's distributional equilibrium, ALCM  does not appear to occur at latitudes less than 
approximately 38°.  It is absent from southern Sp ain and does not occur in Israel where there are 
extensive apple orchards.  This minimum latitude  value needs to be confirmed by more detailed 
investigation.  In the USA, ALCM is absent from the southern states of Carolina and Georgia 
although it is present in New York State and has spr ead westward from there.  The most northerly part 
of New Zealand is about 35°. 
540. Based on this evidence, it seems unlikely that ALCM would pose a significant threat in areas 
north of ~38° latitude in Australia.  So the threat of ALCM invasion appears to be confined largely to 
SE Australia and Tasmania. 
541. ALCM needs sufficiently long cool (< 5 C°) periods in winter for diapause breaking and 
reasonably regular summer rainfall to survive.  Th e winter chill intensity and duration requirements 
for diapause breaking have not been established nor have the summer rainfall requirements.  
However, the current distribution provides evidence  to establish limits.  For rainfall for instance, 
ALCM has established in areas of Washington State, USA, west of the Rockies, but is as yet absent to 
the east of the Rockies where th ere is little summer rainfall and a pples are grown using irrigation 
water.  Climatic conditions in SE Australia, which have been exceptionally hot and dry, have been 
quite unsuitable for ALCM survival. 
542. The current distribution of ALCM could have b een used to establish climatic conditions that 
are especially favourable to ALCM and climatic bounda ry conditions for its existence.  A climatic 
analysis would also have given a better assessment of the likely impact of ALCM in different areas of  WT/DS367/11 
 Page 105 
 
 
  Australia.  However, the IRA did not assume that AL CM would spread to all areas of Australia where 
apples are grown commercially or domestically and the overall assessment is correct. 
543. In conclusion, Australia's IRA was objective a nd credible, but did not draw sufficiently on 
available information and did not conduct a sufficiently detailed analysis. 
(vi) the host range and conditions required for ALCM egg laying  
 
544. It is well known and both parti es agree that apple & related Malus  sp are the only hosts of 
ALCM and that eggs are laid in tender leaves in growing shoots.  In New Zealand, oviposition and 
larval attack has been observed in flowers resulting in damage to young developing fruitlets.  This 
appears to be a very rare occurrence which has onl y been reported from New Zealand.  It evidently 
occurs when there is a heavy ear ly emergence in spring.  Minimal temperatures and maximum wind 
speeds for female flight and ovipos ition have not been quantified. 
(vii) the absence for the need for a vector for ALCM to be able to spread from its initial 
location  
 545. In biology, the term "vector" is normally used  for an organism that transmits infection.  
ALCM does not have a vector in this sense.  In this  context, the term vector is referring to an agent, 
biological or physical, that can passively carry  ALCM.  ALCM females can fly short distances and 
thus it is self evident that a vector for short range spread is not needed.  In successive generations it 
could spread long distances provided there was a chai n host plants each separated by no more than the 
flight range of females.  However, ALCM would require a "vector", i.e. a commodity or conveyance 
with which it could move, for long range spread be tween host plants separated  by greater distances 
than the maximum flight range of fe males.  It is considered that normally ALCM spreads to new areas 
on nursery material.  The question of flight range has been dealt with under (iii) above. 
(viii) the life stage in which ALCM could ent er Australia on export apples imported from 
New Zealand  
 
546. The answer is essentially the same as given in (i) above.  Unless New Zealand can provide 
evidence to the contrary, ALCM could enter Australia as mature 3
rd instar larvae (in the full range of 
stages of diapause) or as pupae (in the full range of  stages of post diapause pupal development) in 
cocoons round the stalk or eye of apple fruits or possi bly attached to bulk bins used in the orchard for 
picking apple fruits. 
547. Australia's IRA relating to this issue was obj ective and credible and relied on what little 
scientific evidence there was but th e available scientific evidence is insufficient for proper resolution. 
Dr Deckers : 
 548. The adult emergence of ALCM will not be immedi ately after the cold storage;  it will take 
some time depending on internal processes of developm ent  of the insect in the pupae that will depend 
on the environmental conditions. 
549. In Europe we have only 3- 4 generations per year, depe nding on the presence of active 
growing shoots on the apple trees where the adults  can put their eggs on the young leaves.  The 
presence of young leaves on active growing shoots is necessary. 
550. The flight range in an orchard is normally limited, but introduction in a newly infected 
orchard indicate a general spread over the whole orchar d in a very short time.  This could indicate that 
wind distribution can play a role.  There is no need for a vector. WT/DS367/11 
Page 106  
 
  551. In Europe the adult life span of ALCM is about 4 weeks for the first generation and 6 weeks 
for the later generations ( Frankenhuizen, 1992, Wa geningen, pp 207-209:  schadelijke en nuttige 
insecten en mijten in fruitgewassen  ; uitgave nederlandse fruittelers  organisatie, NFO, Nederland 
ISBN 90 9002 363 1). 
552. The life stage in which ALCM could enter Austra lia is the larvae in the cocoon externally 
present on the apple fruit.  But the import by contam inated fruit trees is considered to be much more 
important for the introduction of ALCM than the import on infected apple fruits. 
Question 95 
Please comment on whether the evaluation in Austra lia's IRA of the potential entry and establishment 
of ALCM in Australia was objective and credible, relying on respected and qualified scientific sources 
with respect to the life span of ALCM and its flight r ange?  Are the conclusions in Australia's IRA as 
to the relevant probability values in this respect c hosen by the Australia's IRA sufficiently supported 
by the available scientific evidence?  (IRA, Part B,  pp. 175-183;  paras. 4.35 0-4.366 of New Zealand's 
FWS;  paras. 792- 824 of Australia's FWS;  R 83-85 by New Zealand) 
 Dr Cross
: 
 553. With respect to the narrow issue of the life span and flight range of ALCM, the evaluation in 
Australia's IRA was objective and credible (see answ ers to Question 94, parts (iii) & (iv) above). 
554. With respect to the conditions for adult emer gence of ALCM Australia's IRA was objective 
and credible and relied on what little scientific ev idence was available.  ( see answer to Question 94, 
part (i) above). 
Dr Deckers
: 
 555. The chances for a New Zealand apple to b ear a ALCM cocoon is already low and will 
decrease during grading when the fruits are washed a nd brushed.  Crucial point in the further risk 
assessment is the survival rate of  the larvae in the cocoons entering in diapause when they come into 
the storage room and when they come out the storage room some months later. 
Question 96 
Please comment on whether the evaluation in Au stralia's IRA of the potential biological and 
economic consequences of ALCM incursion in Austra lia was objective and credible?  In assessing 
consequences of ALCM introduction, should current or  historical data be considered to be more 
relevant?  (IRA, Part B, pp. 184-187;  paras. 4.367- 4.377 of New Zealand's FWS;  paras. 825-850 of 
Australia's FWS;  R 86 by New Zealand) 
 
Dr Cross
: 
 
556. Australia's methodology for assessing impacts (IRA p 35-40) is qualitative and some of the 
terms used are relativistic and are not clearly defi ned.  In Table 10, much rides on the differences 
between "minor", "significant" and "highly significan t" but the differences between these impacts is 
not defined in terms of economic loss, the need to apply insecticides or social consequences.  Because 
of this, Australia's assignment of an impact score of D (national level-unlikely to be discernable;  
regional level – minor, district level – significant;  local level – highly significant) of the direct 
impacts on plant health is credible though a C rating (district level – minor;  local level - significant) 
in my view would be more appropriate.  ALCM is  a moderately damaging pest in nurseries, in young 
orchards during the early years of establishment and is perhaps most damaging to newly grafted trees.  
In these situations it reduces shoot growth and could reduce the rate at which newly planted orchards 
reach their full cropping potential.  In many count ries where ALCM is ubiquitous and the climate very  WT/DS367/11 
 Page 107 
 
 
  favourable for it (e.g. the UK), growers generally pa y limited attention to it and live with it as a minor 
irritation and do not apply insecticides.  In recent years it has become apparent that  trying to control it 
with broad-spectrum insecticides does more harm than good because such insecticides are harmful to 
the pest's natural enemies and short term gains re sult in longer term resurgences.  Several of the 
important natural enemy groups occur in Australia but the parasitoid Platygaster demades , an 
important natural limiting factor, appears to be absent,  so it is likely that ALCM would be on average 
more damaging than it were if Platygaster demades  were present.  If the ALCM established in 
Australia, its impact could be mitigated by introduction of Platygaster demades .  ALCM damage 
could be reduced by applications of selective insectic ides if such materials beco me available in future 
but currently there are evidently no suitable insecticides for control of ALCM in Australia.  In my 
view, ALCM is significant in particular orchards at a local level and this would deserve a C score. 
557. Reliance on the survey of Nelson growers in  the mid 1990s by Smith & Chapman (1995) 
coupled with the absence of Platygaster demades  has perhaps led to the D categorisation.  However, 
NZ is right to point out that the pest status in NZ  has reduced since the introduction of integrated fruit 
production programmes and a reduction in the use of broad-spectrum pesticides which disrupted 
natural enemies of ALCM.  This mirrors the Eu ropean experience where most growers live with 
ALCM without apparently suffering serious losses and seldom make treatments in newly planted 
orchards to control it. 
558. The impact scores of "A" for direct impacts on human life and other aspects of environmental 
effects in the IRA are objective and credible. 
559. The D categorisation is also somewhat severe in the case of the indirect impact on the 
requirement for control measures and a C rating would be more objective and credible.  The control or 
eradication alternatives are very different and should not be lumped together.  Eradication of a first 
initial outbreak would certainly be difficult and costly  and would justify a D score.  It would require 
the grubbing of the infested trees or orchard (s) and of others in the vicinity.  The consequences of 
doing this would very much depend on the local ci rcumstances and how extensive the initial outbreak 
had become before it was first detected.  If an a ttempt was made to eradicate the pest from a whole 
district, an E score would be appropriate.  Howe ver, as stated above, the consequences of possibly 
having to apply control measures in nurseries on newly planted orchards at a local level only justifies 
a C score. 
560. The categorisations in the IRA of the impact of ALCM on domestic trade or industry, 
international trade and environment and community ar e credible and objective.  However, effects of 
ALCM infestation on skin finish or fruit quality ar e rare.  The type of damage reported from New 
Zealand has not been reported from elsewhere and is  extraordinary.  The international trade rating 
would very much depend on the scale an d importance of exports from Australia. 
561. However, the re-categorisation of the direct im pacts on plant health and the need for control 
treatments would not result in a change in the rating of the overall consequences as "low".  In this 
respect, the conclusion of Australia's analysis was objective and credible. 
Dr Deckers : 
 562. Why not decide on the need for a fumigation only when there is a problem with ALCM found 
on an apple in the orchard or during grading and pack ing;  this would allow to reduce the risk of a 
potential introduction into Australia substantially. 
563. The problem of an ALCM infection in an appl e orchard is not considered in Europe as a 
major problem, but more as  a secondary parasite that makes some damage on the leaves without 
interfering too much with the productivity of the fruit trees. WT/DS367/11 
Page 108  
 
  Question 97 
Please comment on whether the consideration in Aust ralia's IRA of the mortality and occupancy rates 
of ALCM cocoons on New Zealand apples was objective and credible, relying on respected and qualified scientific sources?  Is such consideration su fficiently supported by the available scientific 
evidence?  Did the consideration in  Australia's IRA in this regard take into account relevant viability 
data regarding ALCM insects or cocoons present on New Zealand apples, from respected and 
qualified scientific sources?  (Paras. 67 and 103 of New Zealand's opening statement and Exhibit NZ-
102;  paras. 731 and 734 of Australia's FWS;  and R 87 and R 88 by Australia) 
 
Dr Cross
: 
 
564. The sources of data on occupancy and viability of ALCM in cocoons on New Zealand apples 
are very sparse.  In my view the data on viability rat es is very critical and the data is inadequate for an 
objective and credible assessment. 
565. Two estimates are available for occupancy rates:  In one survey of 30 blocks of Braeburn in 
the Waikato region and one in the Bay of Plenty in April – May 1994, 63% of cocoons were found to 
be empty (Tomkins et al, 1994; Exhibit NZ 43).  The second study of Rogers et al. (2006) (Exhibit 
NZ 17) gives estimates of 36.6%-42.2 % empty cocoons on samples from 3 different varieties from the Nelson region in 2005. 
566. Good data provided by NZ from endpoint insp ection of 4,556,564 fruit over the years 2001-
2004 from which a total of 7297 occupied cocoons were found is presented in Table 40 of IRA and 
used to set appropriate values for the probability of  importation.  The data in the table refers to 
occupied cocoons (unoccupied cocoons are evidently not  reported).  It is regrettable that the viability 
and parasitism rates of this large sample were not determined.  Thus, the only data on the viability of 
ALCM in occupied cocoons is that of Rogers et al. (2006) (Exhibit NZ 17) from samples from 3 different varieties from the Nelson region in 2005.  In this study estimates were made of the % of 
occupied cocoons that contained viable pupae.  Larv ae or pupae that were shrivelled were considered 
to be non-viable.  Australia is al so right to question the use of the prodding test to establish whether or 
not non-shrivelled individuals are alive or dead as this would not be a very accurate test.  Some 
individuals that did not move in response to prodding  could be viable.  Rearing to adult is necessary 
for establishing mortality.  However, if this we re done it could well be found that mortality is 
considerably higher than establis hed by examination and prodding. 
567. The original paper was ambiguous in the way the data on mortality was reported as it was 
unclear whether the % mortalities were expressed as a percentage of the whole sample (including 
occupied and non-occupied cocoons) or just of the o ccupied cocoons.  This was clarified in the letter 
of the author of the paper to Biosecurity NZ of 18 August 2008 (Exhibit NZ 102).  A value of 75.1% mortality of occupied cocoons is given in this  letter. Values for % mortality ranged from 45.2 to 
93.9% in the 24 samples of 25 Braeburn fruits reported.  Unfortunately, there are several 
discrepancies between the values pr esented for the % mortality based on all cocoons in original paper 
and in the letter which brings the soun dness of the data itself into question. 
568. The outcome of this is that there is only one bulk estimate of the mortality % of occupied 
cocoons of 75% from the Rogers et al  (2006) data.  This data  is not sufficient for a reliable estimate of 
this parameter or of its variability.  Given the cr ucial importance of viability in calculating risks and 
determining appropriate sample sizes it does seem im portant that a more rigorous study is conducted 
over several seasons.  Australia's IRA does need to take viability into account.   Until good data is 
produced, it would be entitled to conservative estim ate of 50% viability (= 50% mortality) given the 
lack of data and likely variable  nature of this parameter.  WT/DS367/11 
 Page 109 
 
 
  Dr Deckers : 
 569. The mortality of the ALCM cocoons is an im portant discussion point between both countries, 
but what I miss in the publication of Rogers et al. 2006 is the real level of survival of the cocoons hatching to new adult insects after the whole traject of exportation and transportation. 
Question 98 
Please comment on whether the proportion of apples shipped from New Zealand to Australia in packages ready for retail use (i.e., retail-ready),  compared with the proportion shipped from 
New Zealand to Australia in bulk, subject to packaging prior to retail sale, is relevant for the assessment of the likelihood of entry, establishment or  spread of ALCM?  If yes, how?  (IRA, Part B, 
p. 9;  R 8-10 by the Parties)  
Dr Cross
: 
 570. With respect to ALCM, the proportion of apples sh ipped retail ready from NZ to Australia is 
crucial.  If all fruit were shipped as retail ready a nd held in a cool chain conditions until sold to 
consumers, the risk of importation, establishment and spread would be greatly reduced, perhaps to 
negligible levels.  The arguments presented in pa ras 4.361 – 4.363 of NZ FWS with respect to this 
appear valid. 
571. The effect of the proportion of apples shipped retail ready on the risk is also evident in 
Australia's IRA.  The probabilities presented in Tables 44 and 45 of Australia IRA part B 175-183 
with respect to commercial fruit crops arriving at the 7 orchard wholesalers are very much higher than 
the risks associated with the other utility points and are thus particularly critical to the overall risk 
assessment. 
572. The quantities of fruit and the way they are is he ld and handled, if at all, at these 7 orchard 
wholesalers, which evidently are in close proximity to apple orchards (Aus exhibit 66 shows a helpful 
aerial photo of one orchard wholesaler and the orchards  in the vicinity), appears to be critical.  Two 
very different scenarios would give very different ri sks of entry and establishment:  1) Higher value, 
retail ready fruit in packs or cartons ready for sale he ld in cold stores and redistributed to markets with 
minimal breaks in the cold chain and minimal losses resulting in disposal of fruits in the vicinity of 
orchards.  The potential risks in this scenario are very low:  There would be virtually no opportunity 
for ALCM adults to emerge, mate, exit the pack ho use and locate a susceptible apple tree.  2) Fruit 
arriving in bulk bins being graded and packed, or perhaps fruit being repacked with larger volumes of 
discarded fruit being held temporarily at ambient te mperatures outside before being disposed of 
perhaps nearby in the vicinity of an apple orchar d.  The potential risks for this scenario are much 
higher.  It appears to be because of this analys is that the overall IRA for ALCM is comparatively 
high. 
573. Tables 42 and 43 of the IRA present a very wide  range of values for the weekly indicative 
estimates of numbers of apples arriving at the 7 orchard wholesaler utility points as well as ay the 
other utility points.  Data in Table 42 should be di scarded as it relies on old inadequate published data.  
The estimates in Table 43 should be used because they are based on recent, good quality data taken 
from large numbers of samples over 4 years.  Austra lia does not appear to have challenged the quality 
or provenance of the August 2005 data presented in  IRA Table 40 but continues to give the old 
estimates (based on much more limited data) equal weight.  In response to recent questions, NZ 
confirmed that the fruit was not subject to mitigation procedures or handled in any way to reduce the incidence of ALCM cocoons.  They have also confir med that the efficacy of detection of cocoons is 
very high, close to 1.0. WT/DS367/11 
Page 110  
 
  574. Within the cells of Table 43 two estimates of the numbers of apples arriving at utility points 
are given based on two extreme scenarios, 0.1%-5% of imported apples being distributed to orchard 
packing houses and the remainder (95%-99.9 being di stributed to one urban wholesaler).  The other 
scenario was based on 70-100% of imported apples being distributed to the orchard wholesalers  1) in 
an upper row of values based on P1 = Uniform (10
-3, 5 x 10-2) and  2) the lower row of values based 
on P1= Uniform (0.7,1).  The values for urban wholesal er are inverted because of the assumption that 
if fruit didn't go to the orchard wholesalers then it w ould go to the urban wholesaler.  The median and 
mean value estimates based on these widely varying P1  values vary by a factor of 33.  But if no fruit 
were handled in this way at the 7 orchard wholesalers or the urban wholesaler, the high risks should be excluded from the IRA. 
575. Furthermore, packed and graded ready-for-sale fruit is unlikely to have green leaf material 
attached and the packaging itself would be much less likely to be infested wi th ALCM than say bulk 
bins into which the fruit was picked in the orchard, further reducing any risks. 
576. In conclusion, requiring fruit to be packed a nd graded in NZ ready for sale would be an 
effective SPS measure to minimise the risk of ALCM entry and establishment in Australia.  SPS 
measures would need to deal with the critical issu e of disposal of waste fruit well away from apple 
trees.  No detailed study has been presented by NZ  to quantify these risks in similar pack houses in 
NZ. 
Dr Deckers
: 
 577. The risk for importation of the ALCM into Aust ralia is greater for the apples exported in bulk 
than in ready-retail.  By the preparation read -retail part of the cocoons can be washed of. 
Question 99 
Please comment on whether the consideration in Au stralia's IRA of the likelihood of entry and 
establishment of ALCM through mature apple fruit from New Zealand was objective and credible, 
relying on respected and qualified scientific sources with respect to the level of infestation of viable 
ALCM cocoons on New Zealand apples?  Is such cons ideration sufficiently suppor ted by the available 
scientific evidence?  From the information provided in the IRA, is it possible to determine the impact 
considered by the IRA of factors such as cocoon viability rates and the biology of ALCM on the likelihood of entry, establishment and spread of ALCM?  (IRA, Part B, pp. 161, 163, 166 and 171;  paras. 4.106-4.133 and 4.334-4.366 of New Zealand' s FWS;  paras. 721-824 of Australia's FWS) 
 Dr Cross
: 
 578. The IRA estimation of the probability of impor tation using an assessment of 8 importation 
steps lead to a much higher estimate of the mean  infestation rate of imported fruits of 4.1 x 10
-2 
(mean), 2.1 x 10-2 (5th percentile) and 6.5 x 10-2 (95th percentile) (IRA Results importation, p165) 
than the findings from the end point inspections presented in Table 40 which led to a most likely 
value of 1.3 x 10-3 being estimated (minimum 10-3, maximum 3.8 x 10-3).  The first estimate of the 
mean infestation rate is 31.5 times higher than  the second.  In my view the second estimate is the 
more trustworthy because it is based on actual observations of large samples taken over 4 years.  The first estimate should be discarded as the risk estimates  at critical importation steps are subject to large 
uncertainties because they  are based on inadequate old published data. 
579. The data in Table 40 gives the frequency of occurrence of occupied cocoons.  The actual 
infestation rate of viable cocoons  would be substantively lower as a significant proportion of occupied 
cocoons are not viable (see answer to Question 97  above).  Data on this aspect is comparatively 
scanty so a conservative estimate of 50% cocoons occupied by viable larvae or pupae might be 
appropriate given the likely variab le nature of these parameters.  WT/DS367/11 
 Page 111 
 
 
  Dr Deckers : 
 580. In the whole discussion of the introduction of the ALCM trough mature apple fruit from New 
Zealand I don't see scientific data indicating that th e occupied cocoons after storage are able to hatch 
and to form viable adult ALCM.  This is an important information you need when you want to 
evaluate the risk of introduction. 
Question 100 
Please comment on the relevance, if any, of seasona l population development (i.e. whether by harvest, 
some adults may have emerged leaving behind thei r empty cocoons) and of par asitism by Platygaster 
demades, or both, on the evaluation in Australia 's IRA regarding the viability of ALCM cocoons on 
New Zealand apples.  (IRA, Part B, pp. 159-160;   paras. 4.108 of New Zealand's FWS;  and 
paras. 845-846 of Australia's FWS) 
 
Dr Cross
: 
 
581. Seasonal population development is  highly relevant.  By harvest 3 generations of ALCM or 
more would have occurred and a substantial proportion are likely to have emerged, leaving behind 
their empty cocoons.  In each generation a proportio n of larvae may go into diapause and not emerge 
till the following year or the year after that.  Th e proportion doing this varies considerably between 
generations and years.  Barnes 1948 gives an ex cellent overview of extensive earlier studies by 
Whitcomb in Massachusetts in the late 1930s and early 1940s. 
582. As stated in the answers given to Question 97 above, the survey of Tomkins et al (1994) 
found 63% of cocoons were found to  be empty and the second study of Rogers et al (2006) (Exhibit 
NZ 17) gives estimates of 36.6%-42.2 % empty cocoons.  These are two snap shots of what is likely to be a very variable parameter, due to variations  in the availability of shoot growth and temperature 
and rainfall patterns as well as geographical and topo graphical variations.  Be tter data is required. 
583. However, it is important to remember that the August 2005 data gives rates of infestation by 
occupied cocoons (so the numbers of  empty cocoons is not included). 
584. Parasitism by Platygaster demades  would also reduce the proportions of viable cocoons.  
Todd (1959) reports parasitism rates of 61.7, 78.7 and 47.3 in the 3rd generation larvae in the 1955-
56, 1956-57 and 1957-58 seasons respectively.  Par asitism in the second generation was much lower 
due to asynchrony of host and parasitoid pop ulations.  However, parasitism in the 3
rd or possibly 
4th generation are likely to be more relevant as apple fr uits are most likely to be infested with cocoons 
from the generations which occur close to harvest.  This is clearly a significant though highly variable 
factor. A conservative estimate might consider 30%  of cocoons to be parasitised on average. 
Dr Deckers : 
 
585. The number of generations of ALCM can be different from one year to another and the 
population development will depend also on the presen ce of shoots in an active growing stage in the 
orchard.  When there is a severe drought period, th e vegetative growth of the trees can be stopped and 
this can have a decisive influence on the furt her development of the populations of ALCM. 
586. The parasitism of ALCM by Platygaster demades  can influence the final survival of the 
ALCM.  Therefore it is important to know the number of the hatching adults coming out of the 
cocoons at the end of the whole export process. WT/DS367/11 
Page 112  
 
  Question 101 
Please comment on whether the consideration in Au stralia's IRA of the likelihood of entry and 
establishment of ALCM through mature apple fruit from New Zealand was objective and credible, 
relying on respected and qualified scientific sources with  respect to the possibility that clean fruit 
could be contaminated by ALCM during picking and transport through any leaf material.  Is such 
consideration sufficiently supported by the availabl e scientific evidence?  Did the consideration in 
Australia's IRA in this regard take into account  relevant viability data regarding the possibility of 
damage or infestation on leafy stipules?  (IRA, Part B, pp. 161;  paras. 4.113 of New Zealand's FWS;  and paras. 739-740 of Australia's FWS) 
 Dr Cross
: 
 587. At picking, depending on the firmness of attachment of the fruit, the way the fruit is picked 
and the degree of care taken to re move leaf material from picked fruits, a proportion of fruit will have 
mature leaves and leafy stipules attached.  Howeve r, at harvest these leaves and leafy stipules are old 
and unlikely to be infested with ALCM.  During picking, some mature larvae (and perhaps the odd 
ALCM gall) may fall from infested shoots above into the picking bucket and be transferred to the bulk 
bins where they may further contaminate fruits or th e bins themselves.  If bins were under the trees or 
the trees were tall, some larvae, leaf material possibl y including occupied galls.  The degree of leaf 
contamination in bulk bins is likely to be very variable, but could be  high (Aus exhibit 64 illustrates 
that high levels of leaf contamination in bins can occur). 
588. The leaf material does therefore pose some limited additional risk of increasing the frequency 
of fruit contamination by ALCM compared to the situ ation just prior to picking.  However, the August 
2005 endpoint inspection data  will have already taken that into account with respect to the fruits. 
589. The values given in the IRA Importation step 3 (page 161) for the likelihood that clean fruit is 
contaminated by apple leaf curling midge during pi cking and transport to the packing house is given 
as Uniform(10
-3, 5 x 10-2).  The basis for these estimates is unclear. 
590. If fruit imported is into Australia prior to grading and packing in these bulk bins which 
contain leafy material, the leafy material and the bi ns would pose an additional risk to the fruit alone 
because there is a significant chance both leafy materi al and bins would be contaminated with ALCM 
cocoons. 
591. However, there is a requirement for the apples to be free of trash.  Furthermore, as stated 
above, if the fruit is retail ready and already packed and graded in NZ, the risks would be negligible 
Uniform (0, 10-6).  Furthermore, if the use of NZ Aug 20 05 end point inspection data is accepted, no 
additional risk should be attributed as it is already taken into account. 
Dr Deckers : 
 
592. This way of infection of the clean fruit dur ing picking or trough leaf material is not 
considered to be a real infection possibility and is not sufficiently covered by scientific science 
references.  The leafy stipules are not the type of l eaves that are infected by the ALCM ; the leaves in 
the top of the shoots are the ones that are infected.  WT/DS367/11 
 Page 113 
 
 
  Question 102 
Please comment on whether the consideration in Au stralia's IRA of the likelihood of entry and 
establishment of ALCM through mature apple fruit from New Zealand was objective and credible, 
relying on respected and qualified scientific sources with respect to the effects that cool storage of 
apples has on attached ALCM cocoons, specifically relating to the delayed developmental stage of 
diapause?  Is such consideration sufficiently suppor ted by the available scientific evidence?  Did the 
consideration in Australia's IRA in this regard take into account relevant data regarding the life 
stages at which ALCM can enter diapause, the conditions required for adult emergence of ALCM from diapause and the time that it takes for adult emergence to occur following completion of 
diapause?  (Paras. 4.118-4.120, 4.131 and 4.3 55 of New Zealand's FWS;  paras. 765-766 of 
Australia's FWS)  
Dr Cross
: 
 593. This question has already been an swered in detail in the response to Question 94 part (i) the 
conditions for adult emergence of ALCM. 
594. The overall effect of the range of ALCM deve lopment stages and conditions to which they 
would be exposed after transport to Australia is a prolonged period of emergence of viable 
individuals.  This substantially decreases the chan ces of a male and female emerging within the time 
frame of a few days which is required for successf ul mating.  The risk of establishment is thus 
substantially reduced and this importa nt factor has not been taken into account in Australia's IRA or in 
the subsequent intercourse between the parties.  So me important further analyses is provided in the 
answer to question 104. 
Dr Deckers
: 
 595. It is not clear in the scientific literature wh en the ALCM will produce adult insects hatching 
from the cocoons after the diapause imposed by th e cold storage period under normal atmosphere 
condition or under controlled atmo sphere condition, with low oxyge n and CO2 concentrations.  The 
presence of young leaves on the shoot tips is also  a necessary condition for a successful introduction 
of the ALCM in a new area. 
Question 103 
Please comment on whether the consideration in Au stralia's IRA of the likelihood of entry and 
establishment of ALCM through mature apple fruit from New Zealand was objective and credible, 
relying on respected and qualified scientific sources with  respect to the flight distance of male and 
female ALCM?  Is such considera tion sufficiently supported by the av ailable scientific evidence ?  Is 
the reasoning articulated by the IRA on the bas is of such scientific evidence, including the 
methodologies applied, objective and coherent?  Do th e results of the IRA's a ssessment in this regard 
sufficiently warrant the challenge d requirements relating to ALCM?  (IRA, Part B, pp. 168-171;  
para. 4.123 of New Zealand's FWS;  and par as. 802-804, 806 and 923 of Australia's FWS) 
 
Dr Cross
: 
 596. This question has alread y been answered in my response to  Question 94 part (iii) the flight 
range of ALCM. 
597. Australia's IRA with respect to  this issue was objective and plausible and relied on what little 
real evidence there was, but the available evid ence was insufficient for a scientifically sound 
assessment. WT/DS367/11 
Page 114  
 
  Dr Deckers
: 
 598. The fact that the flight distance of the ALCM is  limited in distance, reduces the real risk of 
contamination starting from apples carrying the pupae of the insect. 
Question 104 
Please comment on whether standard statistical techniques support the view that a 600 fruit sample 
would provide 95% confidence that no more than 0.5% (1 in 200) fruit have cocoons? 
 
Dr Sgrillo
: 
 
599. The threshold infestation (minimum infestation that could be detected) of an inspection 
system, for large lots, sufficiently mixed, may be calculated rearranging formula 4 of the Appendix 3 of the ISPM 31.
63 
()
eCL11TIn1
−−=
 
 
Where TI is the threshold infestation, CL is the confidence level, n is the number of 
units in the sample and e is the efficacy of the detection method. 
600. Making the confidence level equal to  0.95 (95% ), the sample size equal to 600 fruits and the 
efficacy of the method equal to 1 (100%), then th e threshold infection would be 0.005, what means 
that the sample  would contain, at least, one fruit with coc oons, if 0.5%, or more, of the fruit in the lot 
are infested.  This is true if the efficacy of the insp ection is 100% (every infested fruit in the sample is 
detected). 
Please comment on whether an infestation level of 0. 5% of apple fruit with ALCM cocoons would be 
enough to initiate an ALCM population?  What are the factors that would be relevant in the 
consideration of the risk of establishment of ALCM?  (IRA, Part B, Table 40, p. 166;  paras. 4.127 and 4.137 of New Zealand's FWS;  and paras. 734-736 of Australia's FWS) 
 Dr Sgrillo
: 
 601. To evaluate if 0.5% of fruit with ALCM cocoons would be enough to initiate an ALCM 
population it should be considered that founder popul ations are typically small and consequently are 
at great risk of extinction.  Generally, the smaller the founder population, the less likely is 
establishment.  Though many scientists have referred to  a "minimum viable population" there is rarely 
a distinct threshold.  Instead it is more realistic to consider the probability of establishment as being a 
continuous function of the initial po pulation size.  This function reflects many characteristics of the 
species, such as its intrinsic rate of reproduction,  mate location abilities, and genetic diversity.
64 
602. It is important to consider also that the disp ersal pattern and the probability of finding a mate 
are critical for pest establishment.  Insects that ma te before dispersal have  a higher probability of 
establishment.  In the destination area, the initial pop ulation numbers are extremely low.  So if insects 
disperse first, then they will probably never find a mate.  This is true even for insects with very 
                                                      
63 (footnote original ) Exhibit AUS-30:  International Plant Protection Convention, International 
Standard for Phytosanitary Measures No. 31:  Methodologies for sampling of consignments, 2008, from Report 
of the Third Session of the Commission on Phytosanitary Measures, Rome, 7-11 April 2008. 
64 (footnote original ) Reference 01 Liebhold, A.M., W.L. Macdonald, D. Bergdahl, and V.C. Mastro. 
1995.  Invasion by Exotic Forest Pest s:  A Threat to Forest Ecosystems.  Forest Science Monographs  30.49 pp.  WT/DS367/11 
 Page 115 
 
 
  sensitive pheromone communication mechanisms65, as ALCM.  IRA describes the reproductive 
strategy of ALCM, informing that the males emerge  1-2.5 hour earlier than females.  There is no 
information whether the males disperse just after emergence or not.66 
603. A rough evaluation can be done, considering that theoretically  a couple of adults with the 
right age and conditions, in the right time and at the right place could initiate a population. 
604. Considering a sex ratio of 0.667 (1.5 females per male) it would be necessary 3 viable pupae to 
obtain a couple of adults.  To estimate the number of fruits that carries 3 pupae it is necessary first to 
estimate the proportion of fruits that have alive pre-pupae.  This is calculated multiplying the 
proportion of cocoons that have a pre-pupa (at the harvest) by the proportion of pre-pupae that is 
alive.  The available data to estimate this proportion is variable.  Tomkins et al. (1994)68 estimates that 
37% of the infected fruits have a pre-pupa while Rogers et al. (2006)69 estimates that 60% of the 
infected fruits have a pre-pupae.  This author estim ated also that 41.1% of the pre-pupae are alive.  
These numbers generates proportion of 0.15 and 0.25, respectively, of infected fruits with viable 
pupae.  The number of fruits necessary to obtain 3 viable cocoons if estimated dividing 3 by the proportions (0.15 and 0.25) what generates 20 and 12 fruits respectively.  Finally if 0.5% of the 
population is infested then it will be necessary 4,000 and 2,400
70 fruits disposed in the same place and 
almost in the same time, respectively, to ge nerate 1 pair of adults that could mate. 
605. In the real world would be necessary much mo re than a pair of adults to start a new 
population because many low probability events have to take place successively for a population to 
establish. 
606. Also the data available is not fully reliable. Rogers et al. (2005) states:  "Naturally infested 
apples were selected from Nelson orchards with  uncharacteristically high levels of ALCM  during 
2005".  Therefore the data is not representativ e of the average New Zealand conditions.  The 
experiment of Tomkins et al. (1994) was developed in Waikato and Bay of Plenty that contains only 
3%71 of the pip fruit production in New Zealand.  See also response 108. 
Dr Cross (Response to whole question) : 
 
607. Standard statistical techniques do support the vi ew that a 600 fruit sample would provide 95% 
confidence of no more than 0.5% (1 in 200 fruit have cocoons) providing that the efficacy of detection 
is 100%, i.e. all the cocoons on the sampl e would be detected on examination. 
608. The sampling is destructive (i.e. each apple samp led is not returned to the whole lot where it 
would be equally likely to be re-sampled), it is assumed that the midge cocoons are randomly 
distributed so the underlying distribution is the hy pergeometric.  The methods and calculations are set 
                                                      
65 (footnote original ) Dr Alexei Sharov (Virginia Polytechnic Institute and State University - personal 
communication). 
66 (footnote original ) IRA p. 176. 
67 (footnote original ) Reference 06:  Heath, J et al. Flight Activity and Further Evidence for a Female-
Produced Sex Pheromone of the Apple Leaf Midge, Dasineura mali, in Nova Scotia.  Northeastern Naturalist 
12(1):  93-102. 2005. 
68 (footnote original ) Exhibit NZ-43:  Tomkins AR, Wilson DJ, Hutchings SO and June S (1994) "A 
survey of Apple Leafcurling Midge (Dasyneura mali) management in Waikato Orchards", Proceedings of the 
47th New Zealand Plant Protection Conference, 346-349. 
69 (footnote original ) Exhibit NZ-17:  Rogers DJ, Walker JTS and Cole LM (2006) "Apple Leafcurling 
Midge Cocoons on Apple:  Pupal Occupancy and Mortality", HortResearch, Havelock North, New Zealand. 
70 (footnote original ) 12 fruits/0.005 (infestation)=2400 fruits;  20 fruits/0.005=4000 fruits. 
71 (footnote original ) Exhibit NZ-3:  Pipfruit New Zealand Incorporated (2006 and 2008) Pipfruit 
Industry Statistical Annuals, January 2006 and March 2008, New Zealand pp. 18 and 20. WT/DS367/11 
Page 116  
 
  out in ISPM No. 31 Methodologies for sampling of c onsignments (Aus Exhibit 30).  Table 1 gives the 
numbers of fruit that would need to be sampled from for lots of increasing size at the 95% and 99% 
confidence levels.  For a lot of >200,000 fruit at th e 95% confidence level, 597 fruit would need to be 
sampled for a 0.5% level of detection, close to  the 600 fruit sample size specified, taking New 
Zealand's assurances that the efficacy of detection is close to 1.0. 
609. However, assuming that the sampling proportion is  small (i.e. the number of fruit sampled is 
small compared to the size of the whole lot), the bi nomial approximation (Table 3) is a reasonable one 
for the hypergeometric (this is equivalent to assu ming sampling with replacement).  This is much 
easier to calculate: 
prob(≥ 1 infected fruit) = 1 – prob(zero infected fruit)  = np) 1(1−− 
 For the figures given, with n = 600 & p = 0.005, prob = 0.0494 (close to 0.05, 
i.e. 95% confidence) 
610. Alternatively, to evaluate n for a given underl ying p and required confidence level 95%, the 
calculation is 
) 1(log)05.0(log
pn
ee
−=
 
 
611. Thus, with p = 0.005, n ≥ 598,  i.e. a sample size n of approximately 600 as suggested. 
612. Values for 95% and 95% confidence levels for di fferent levels of det ection and different % 
efficacies are set out in Table 3. 
613. An infestation level of 0.5% of apple fruit with ALCM cocoons woul d be enough to initiate 
an ALCM population providing a sufficiently large number of fruits were disposed of within the 
female flying distance of an apple tree. 
614. The main factors that are relevant in the cons ideration of the risk of establishment of ALCM 
are: 
(a) The % fruits infested with occupied ALCM cocoons 
(b) The proportion of these occupied cocoons that contain viable ALCM 
(c) The proportion of ALCM that are parasitized by Platygaster demades  
(d) The sex ratio of the ALCM cocoons (it is assumed that the sex ratio is 1:1) 
(e) The period over which emergence occurs and it's statistical distribution 
(f) The numbers of fruits placed or disposed of in close proximity to each other 
(g) The distance of the site of disposal to the nearest apple trees 
(h) The time of season, weather and the presence or otherwise of growing shoots on the 
apple trees 
615. Below the probabilities of at least 1 male and 1 female emerging from different numbers of 
fruit placed or discarded within the flight range of  ALCM females of a susceptible host with initial  WT/DS367/11 
 Page 117 
 
 
  infestation rates of 0.5%, 0.1% and 0.05% are calculate d.  Note that this does not take into account the 
fact that actual infestation rates would be reduced by mortality and parasitism nor the greatly reduced 
probability of two individuals emerging within a life span time frame of each other over a protracted 
period of adult emergence, which would further re duce the effective infestation rate substantially . 
616. Using the same notation as above (a sample of  n from a large population N (N>>n), with an 
underlying probability of infestation of p), we want to  calculate the probability of at least 1 male and 1 
female emerging from a sample.  Assuming the binom ial distribution can be used as an approximation 
to the hypergeometric distribution and also assumi ng that males and females are equally likely and 
that there is never more than one infection per fruit: 
617. Let k = number of infected fruit, p s = probability of all one sex (i.e. not at least one male of 
one female), prob(k) = prob of k infected fruit from binomial distribution. 
618. If in the sample there are no infected fruit or only 1 infected fruit then there is no chance of 
having at least 1 male and 1 female. 
619. If in the sample there are 2 or more infested fruit p s = prob(k)/2k – 1  as for k ≥ 2 there are 2k 
different (ordered) combinations of males and fe male (e.g. for k = 3 can have MMM, MMF, MFM, 
FMM, MFF, FMF, FFM, FFF) of which 2 (MMM, FFF) will all be the same sex, so probability of k 
infested fruit with all same sex = prob(k) × 2/2k. 
620. Thus Prob(at least one male and 1 female) = p mf = 1 – prob(0, 1 infested fruit) – prob(all same 
sex) 
= 1 2
21) 1( ) 1( ) 1(211− −
=−−−−−−⎟⎟
⎠⎞
⎜⎜
⎝⎛−∑n n k kn
kkp np p p pkn
 
 621. The final two terms are the probability of 0 and 1 infested fruit respectively. 
622. It is not possible to re-arrange the above formul a to calculate n for a given probability of at 
least 1 male and 1 female, but it is possible to calcula te that probability for various values of n.  Using 
the GenStat statistical package, it is possible to do this using the above formula for n ≤150, but the 
factorial parts of the formula then  become too large; for 150 < n  ≤ 1000 the program uses the 
probability function for the Binomial distribution.  Af ter n = 1000, this part of the program also fails 
to work because of large numbers w ithin the calculation.  It is likely that there are other numerical 
methods to do this calculation for n > 1000 if one cared to investigate. 
623. The Table overleaf gives estimates of the probab ility of at least 1 male and 1 female emerging 
from different numbers of discarded fruit (n) where the initial infestation rate of occupied cocoons is 
0.5%, 0.1% or 0.05%.  
  WT/DS367/11 
Page 118 Table of probabilities of at least 1 male & 1 female for infestat ion rates of 0.5%, 0.1% and 0.01% with viable cocoons for give n n 
n p mf n p mf 
 0.5% 0.1% 0.05%  0.5% 0.1% 0.05% 
        
25 0.0035 0.000148 0.000037 525 0.5346 0.05325 0.01511 
50 0.0136 0.000598 0.000151 550 0.5587 0.05775 0.01648 
75 0.0290 0.001338 0.000341 575 0.5818 0.06238 0.01791 
100 0.0487 0.002357 0.000604 600 0.6040 0.06712 0.01938 
125 0.0718 0.003645 0.000940 625 0.6252 0.07198 0.0209 
150 0.0976 0.005191 0.001346 650 0.6454 0.07694 0.02247 
175 0.1254 0.006986 0.001823 675 0.6647 0.08200 0.02409 
200 0.1547 0.009019 0.002368 700 0.6831 0.08716 0.02575 
225 0.1850 0.01128 0.00298 725 0.7007 0.09241 0.02746 
250 0.2159 0.01376 0.003658 750 0.7173 0.09774 0.02921 
275 0.2472 0.01646 0.004400 775 0.7331 0.1032 0.031 
300 0.2784 0.01936 0.005206 800 0.7481 0.1086 0.03283 
325 0.3095 0.02245 0.006074 825 0.7624 0.1142 0.03471 
350 0.3402 0.02572 0.007003 850 0.7759 0.1198 0.03662 
375 0.3703 0.02918 0.007991 875 0.7887 0.1255 0.03858 
400 0.3998 0.03281 0.009038 900 0.8008 0.1313 0.04057 
425 0.4285 0.0366 0.01014 925 0.8122 0.1371 0.0426 
450 0.4564 0.04054 0.0113 950 0.8231 0.1429 0.04466 
475 0.4834 0.04464 0.01252 975 0.8333 0.1488 0.04677 
500 0.5095 0.04887 0.01379 1000 0.8430 0.1548 0.0489 
 
  WT/DS367/11 
 Page 119 
 
 
  624. The 600 fruit sample would provide 95% confiden ce that no more than 0.5% (1 in 200 fruit) 
have occupied cocoons, but the actual infestation ra te would be reduced by a factor 0.5 x 0.7 for 
reduced viability and parasitism and probably by a further factor of 0.1 – 0.5 for the protracted emergence relative to the short life span, actual effe ctive infestation rates of 0.1% or even 0.05% 
would be more realistic. 
625. Note also that the average rate of infestation of NZ apples by ALCM as indicated by the 
August 2005 data is 0.16%, 3 x lower than the 0.5% 95% confidence value that would be detected by 
a 600 fruit sample. 
626. Thus approximately 100, 500 or >1000 fruits would have to be discarded for infestation rates 
of 0.5, 0.1, and 0.05% in one place for a 5% chance  of at least one male and one female emerging to 
start an infestation. 
627. So to answer the latter part of the question, a 0.5% infestation rate of  occupied cocoons would 
have a 5% chance of initiating an infestation if perhaps 500-1000 fruits were discarded in one place 
within the female flight range of a susceptible host. 
Dr Deckers (Response to whole question)
: 
 
628. The estimation of 1 fruit per 200 fruits carrying a cocoon seems to be rather high and indicate 
a relatively high infection pressure in the orchard.  There will be surely circumstances that there will 
be no fresh vegetative growth at the end of the sea son and this factor will reduce the overall infection 
risk seriously. 
Question 105 
Please comment on whether the consideration in Australia's IRA regarding the inadequacy of an 
inspection and treatment system based on a 600 fr uit sample to manage the risk for ALCM was 
objective and credible, relying on respected and qualified scientific sources.  Is such consideration 
sufficiently supported by the avail able scientific evidence?  (IRA, Part  B, p. 188-190;  paras. 1094-
1096 of Australia's FWS;  paras. 4.517-4.522 of New Zealand's FWS) 
 
Dr Cross : 
 629. The adequacy of the 600 fruit sample size will ve ry much depend on the way fruit is handled 
in Australia in particular the number of fruit that are likely to be placed or disposed of in the vicinity 
of an apple tree or trees.  As set out in my an swer to question 98, two very different fruit handling 
scenarios would give very different risks of entry and establishment and quite different sampling sizes 
would be appropriate. 
630. If higher value, fruit is retail ready in packs or cartons ready for sale held in cold stores and 
redistributed to markets with minimal breaks in th e cold chain and there were minimal losses resulting 
in disposal of fruits in the vicinity of orchards, th e potential risks in this scenario are very low:  There 
would be virtually no opportunity for leaf midge adults to emerge, mate, exit the pack house and 
locate a susceptible apple tree.  A 600 fruit sample size would be very adequate to give a very 
minimal risk from disposal of small numbers of fruits by consumers etc in gardens or near orchards etc. 
631. If fruit arrived in bulk bins for grading and p acking with larger numbers of discarded fruit 
being held temporarily at ambient temperatures outsi de before being disposed of possibly nearby in 
the vicinity of an apple orchard, the poten tial risks for this scenario are much higher. WT/DS367/11 
Page 120  
 
  Dr Deckers
: 
 632. The necessity to treat all the lots when a fru it sample of only 600 apples is inspected is 
surprising:  why not only treat the lots of apples wh en they come from an infected orchard or when 
some ALCM have been found. 
633. I don't understand why the fumigation treatment a pplied on the infected apple plots would not 
be able to reduce the ALCM populations sufficiently.  Is there a  clear scientific evidence for this 
view. 
Question 106 
Is the requirement identified in Australia's IRA that a packing house provide details of the layout of 
the premises, sufficiently justified by the scientific evidence relied upon?  (IRA,  Part B, pp. 317;  
para. 4.149 of, and pp. 242 and 247 of Annex 4 to, Ne w Zealand's FWS;  and para. 963 of Australia's 
FWS) 
 
Dr Cross
: 
 
634. It is unclear how a detailed knowledge of pack  house premises in NZ could be used to 
identify areas of risk with respect to ALCM.  Th e locations where end point inspections for ALCM 
and freedom from trash take place clearly do need to be identified. 
Dr Deckers : 
 
635. There is no clear scientific background for this requirement. 
Question 107 
Please comment on what factors, other than the volume of trade in apples between New Zealand and Chinese Taipei, would need to be taken into account to support a contention that New Zealand's 
experience in exporting apples to Chinese Taipei may be used to draw conclusions on the potential 
for ALCM to enter, establish or spread in Austra lia as a result of imports of  apples from 
New Zealand?  (Para. 4.133 of New Zealand's FWS;  para. 819 of Australia's FWS;  R6 by Chinese 
Taipei) 
 
Dr Cross
: 
 
636. The geographic location, the climatic conditions and the availability and locations of suitable 
hosts would need to be taken into account. 
637. ALCM does not appear to occur at latitudes < 38°. Chinese Taipei is at ~25° latitude, much 
too far south to have a climate suitable for ALCM .  Australia FWS para 821, states that Chinese 
Taipei has a subtropical, oceanic climate.  There are no records of ALCM in tropical or sub-tropical 
areas (note also that apple trees are not normally grown in such areas because there is insufficient 
winter dormancy).  If ALCM did temporarily establis h there, populations woul d probably be of short 
duration and may go unnoticed. 
638. Because of the unsuitable climate of Chinese Ta ipei, New Zealand's experience in exporting 
apples to there should not be used to draw conclu sions about the risks of importation into Australia.  WT/DS367/11 
 Page 121 
 
 
  Dr Deckers : 
 639. The climatological situation in both countries as well as the list of possible host plants 
presenting both Australia and Chinese Taipei should be  compared when one wants to compare the risk 
for ALCM introduction in both countries. 
Question 108 
Are the conclusions in Australia's IRA as to  the probability range and distribution patterns 
(triangular distribution with a minimum value of 1.5 x 10E-2, a maximum value of 0.115, and a most likely value of 5 x 10E-2) for importation step 2 sufficiently supported by the available scientific 
evidence? 
 
Dr Sgrillo
: 
 640. The numerical values of the parameters of the di stribution were based in a single survey of 30 
orchard blocks, in 1993-1994 seasons, conducted by Tomkins et al. (1994)
72 as explained by IRA: 
"A survey of 30 orchard blocks in the Wa ikato region and one in the Bay of Plenty 
during the 1993–94 season recorded up to 11. 5% of apples as being contaminated 
with apple leafcurling midge cocoons in the Waikato region, and around 1 to 2% in the Bay of Plenty."
73 
641. The IRA explains also how the distribution and the respective parameters were chosen: 
"The IRA Team decided to represent Imp2 as a triangular distribution with a 
minimum of 1.5 x 10–2, a maximum of 0.115 and a most likely value of 5 x 10–2.  
This was based on the evidence that contamin ation rates for pupae or larvae of apple 
leafcurling midge range from 1–2% to 11.5% of apples in the Bay of Plenty and the Waikato region respectively, and taking into account that these rates are not indicative of apple leafcurling midge abundan ce which is affected by rainfall leading 
to higher levels in wet districts or lower levels in dry districts".
74 
642. In assessing the scientific evidence have to be c onsidered that there is no indication, whether 
these 31 orchards are representative of the populati on of orchards in New Zealand neither if the 
season 1993/94 may be considered typical from the clim atic aspect.  For these data be used with 
confidence would be necessary, also, to evaluate whether the management of orchards in 1993/94 is 
representative of the management of all orchards in New Zealand currently. 
Are the conclusions in Australia's IRA on this i ssue scientifically justified and reasonable?  Do these 
conclusions fall within a range t hat could be considered legitimate according to the standards of the 
scientific community and the methodology applied in the IRA? 
 
Dr Sgrillo : 
 
643. The conclusions were drawn from a survey conduc ted 15 years ago in 31 orchards, in a region 
where only 3% of the pip fruits are grown, wher e the climate is not re presentative and probably, 
where the orchard management were different. 
                                                      
72 (footnote original ) Exhibit NZ-43:  Tomkins AR, Wilson DJ, Hutchings SO and June S (1994) "A 
survey of Apple Leafcurling Midge (Dasyneura mali) management in Waikato Orchards", Proceedings of the 
47th New Zealand Plant Protection Conference, 346-349. 
73 (footnote original ) IRA p. 159. 
74 (footnote original ) IRA p. 160. WT/DS367/11 
Page 122  
 
  644. The conclusions derived from th is data should not be applied to the whole country without 
further consideration. 
Is there any difference in this regard between th e different areas in New Zealand where apples are 
produced for export?  (IRA, Part B, pp. 159-1 60;  para. 4.336-4.338 of New Zealand's FWS;  
paras. 726-738 of Australia's FWS) 
 Dr Sgrillo
: 
 645. Hawkes Bay contains 61% of the pipfruit ar ea for exportation while Waikato contains 3%
75. 
According to New Zealand Waikato have wa rm wet climates, more conducive to ALCM76. 
Dr Cross (Response to whole question) : 
 646. Australia IRA should use the August 2005 end point inspection data provided in table 40 of 
its IRA and discard steps 2 & 3 of its 8 step importa tion analysis.  Step 2 re lies on old and inadequate 
published data and the Augus t 2005 data appears to be of much  better quality being recent and based 
on large sample sizes over 4 years.  New Zealand has given assurances that the August 2005 data was 
not from fruit subject to any risk or infestation mitigat ion procedures and that the efficacy of detection 
is close to 1.  The risk values in step 3 of the IRA appear to be gu esses.  Australia does not appear to 
have challenged the quality of the August 2005 data but continues to give the old estimates based on 
much poorer quality data to which it has given e qual weight.  The most likely value of 5 x 10
-2 for 
importation step 2 results in a 38.5 fold higher estim ation of the most likely risk value for the August 
2005 data (most likely 1.3 x 10-3). 
647. Figures X and Y in Australia's exhibit 51 also present good quality data on the incidence of 
ALCM cocoons on fruit and include additional information on the sma ll percentages of lines that have 
> 2% ALCM as well as  the maximum percentages of ALCM infestation. 
648. There will be local differences in the degree of  infestation but these may vary from year to 
year. 
Dr Deckers (Response to whole question) : 
 649. It is not because the likelihood that picked appl e fruits are infested with ALCM with a value 
of 5x10-E2, that this is the value of the apples that  care the ALCM after storage and after retail-ready 
preparation of the fruits when th ey enter the Australian market. 
Question 109 
In the context of its analysis regarding importati on step 2, does Australia's IRA appropriately take 
into account the "viability" of cocoons?  (IRA, Pa rt B, pp. 159-160;  para.  4.337 of New Zealand's 
FWS;  and para. 729 of Australia's FWS) 
 Dr Cross
: 
 650. The work of Rogers et al (2006) on cocoon occupa ncy and viability is cited in Australia's IRA 
importation step 2 analysis, but then it doesn't appear  to have been taken into account when fixing the 
probability values in the summary analysis of impor tation step 2.  If only 25% of cocoons contain 
viable ALCM then the values should be 4 times smalle r.  In view of the need for caution, 50% might 
                                                     
 
75 (footnote original ) Exhibit NZ-3:  Pipfruit New Zealand Incorporated (2006 and 2008) Pipfruit 
Industry Statistical Annuals, January 2006 and March 2008, New Zealand pp. 18 and 20. 
76 (footnote original ) New Zealand FWS para. 4.336.  WT/DS367/11 
 Page 123 
 
 
  be a suitably conservative estimate of viability, in view  of the paucity of the available data.  However, 
in my view the analysis in step 2 relies on old and inadequate data and the August 2005 data should 
have been used (see above).  The analysis of ri sks does need to take into account parasitism by 
Platygaster demades  and, more importantly, the protracted emergence of ALCM adults relative to 
their short life span. 
Dr Deckers : 
 651. There is no clear scientific evidence of the surv ival of the insects in the pupae stadia of 
ALCM during storage and preparation of the fruits   in the packing houses in New Zealand and 
Australia. 
Question 110 
Please comment on whether the finding in Australia's IRA that Rogers et al (2006) may have underestimated the number of cocoons containing vi able ALCM, because the authors assumed that all 
occupants of the cocoons tested were pre-pupae , is objective and credible, relying on respected and 
qualified scientific sources.  Is such finding sufficiently  supported by the available scientific evidence?  
(IRA, Part B, p. 163;  paras. 4.112 and 4.126 of New Zealand's FWS;  and para. 733 of Australia's 
FWS) 
 
Dr Cross
: 
 652. Above the header to table 2 in Rogers et al (2006) it is stated that "Many of the dissected 
ALCM cocoons contained pre-pupae that were shri velled and obviously dead".  This presumably 
means that prodding was used as a final test on tho se that were not obviously dead and shrivelled with 
death characterised as failure to move when prodde d.  There is some uncertainty here as to the 
proportion of the individuals that were pupae and it is possible that some live individuals were scored as dead as they failed to move when prodded.  Th e prodding test is not particularly good because 
some viable individuals may not move when prodde d.  But equally, a substantive proportion of those 
scored as live because they did move when prodded may have died subsequently and failed to emerge 
as adults.  Australia is right to assert that a better test would have been to see what proportion of individuals actually emerged as adults but such a t est may well have shown even lower viability rates. 
Dr Deckers
: 
 
653. The definition of the pupae to be death was that they don't react when touched by a needle.  It 
would have been better to look to the real number of hatching insects from the cocoons at the end of 
the storage period. 
Question 111 
In the context of importation step 3, are the c onclusions in Australia's IRA in respect of the 
probability range and distribution pattern for fruit contamination by ALCM during picking and 
transport to the packing house (uniform distributio n between 1 x 10E-3 and 5 x 10E-2) sufficiently 
supported by the available scientific evidence? 
 
Dr Sgrillo : 
 
654. The only scientific data provided by IRA is a publication by Tomkins (1998) who found out 
that typically a leafroll contains 20–30 larvae,  but numbers up to 500 have been observed.77 
                                                      
77 (footnote original ) IRA p. 161. WT/DS367/11 
Page 124  
 
  655. There is also another source, identified as "industry sources" estimating a typical figure of up 
to 200 leaves per bin.
78  However further information would be  needed to qualify and establish the 
credibility of these sources. 
656. The quantitative data available do not guarantee that the parameters established describe the 
true population. 
(ii) Are the conclusions in Australia's IRA on this issue scientifically justified and reasonable? 
Dr Sgrillo : 
 657. The conclusions in IRA are a hypothesis about the contamination of the fruits.  This 
hypothesis could be validated when scientific results are available. 
658. However it is not clear which is the main mechanism of contamination of the fruits. 
659. First the IRA Team explains how the contamination may occur: 
"Contamination may occur when infested l eaves are picked during harvest along with 
the fruit".
79 
660. Australia subsequently informed that their main concern is not what is explained in the IRA, 
but the leaves that could be picked: 
"However, the main area of concern fo r the IRA Team was not the chance of 
contamination by ALCM cocoons and leaves directly adjacent to the fruit harvested."
80 
"It is quite probable that pickers will brush against leaves or branches of other parts of 
trees which may sometimes harbour ALCM leaf rolls, occasionally causing ALCM 
larvae to fall from elsewhere on the tree into  a picking bag or bins on the ground."81 
661. The IRA Team does not explain which mechanism was considered to choose the values of the 
parameters of the distribution.  The conclusi ons of the IRA need further justification. 
Do these conclusions fall within a range that could be considered legitimate according to the 
standards of the scientific community and the methodology applied in the IRA?  (IRA, Part B, pp. 161;  
paras. 4.339-4.343 of New Zealand's FWS;  and paras. 741-746 of Australia's FWS) 
 
Dr Cross (Response to whole question) : 
 662. The values given in the IRA Importation step 3 (page 161) for the likelihood that clean fruit is 
contaminated by apple leaf curling midge during pi cking and transport to the packing house is given 
as Uniform (10
-3, 5 x 10-2).  The basis for the choice of values in the estimates is unclear.  The basis is 
given is that the contamination only occurs when infested leaves are picked and the number of leaves 
picked but there is no information on which to quantify the risk.  Uniform(10-3, 5 x 10-2) is a vague 
and wide range of values but Uniform (10-6, 10-3) may have been an equally valid guess! 
                                                      
78 Ibidem. 
79 (footnote original ) IRA p. 161. 
80 (footnote original ) Australia FWS para. 742. 
81 Ibidem.  WT/DS367/11 
 Page 125 
 
 
  Dr Deckers (Response to whole question) : 
 663. There is not sufficient scientific evidence for this  step in the IRA importation step 3.  If there 
are leaves that are harvested, it will be for th e majority leaves coming from the bourse structures 
where the fruits are hanging on.  In addition these leaves are not the leaves where the ALCM midges 
put their eggs on because they prefer the young leaves in the growing shoot tips. 
Question 112 
In the context of its analysis regarding importati on step 3, does Australia's IRA appropriately take 
into account the potential availability of suffic ient flushes of leaf growth suitable for ALCM 
infestation during harvest in New Zealand, given t hat later growth flushes may be stimulated by 
irrigation or wet seasonal conditions?  (IRA, Part B, p. 161;  paras. 4.114 and 4.342 of 
New Zealand's FWS;  and paras. 743-744 of Australia's FWS) 
 
Dr Cross
: 
 
664. In some years in some orchards, there could well be flushes of new growth in the weeks 
running up to and including harvest.  This generally occu rs if the fruit load is light and rainfall occurs 
or irrigation is applied.  However, heavy fruit loads can greatly reduce or shut down shoot growth 
completely in the weeks running up to harvest.  In  the work in NZ, Italy and UK to establish a sex 
pheromone trap threshold for ALCM recently reported in Cross, Hall, Shaw and Anfora, Crop Protection 28(2009), 128-133, it was found that the th ird and fourth generation emergences of adult 
ALCM often occurred when few viable shoots for ga lling were present and this made it difficult to 
establish a valid relationship between trap catches a nd the numbers of galls that developed for the 3
rd 
and 4th generations. 
Dr Deckers : 
 
665. Under standard orchard management condition, the majority of the vegetative shoot growth 
will be stopped some weeks before harvest time.  Ex ceptionally it is possible to have late regrowth 
reactions at the end of the season but phytotechni cally, these reactions have to be avoided because 
these late regrowth reactions mean a loss of terminal flower buds on the shoots. 
Question 113 
Please comment on the data for the period of 2001- 2004 referred to in para. 4.344 of New Zealand's 
FWS, in terms of the possibility that a certain level of viable ALCM could survive packing house, 
quality inspection and export processes, and could arrive in Australia.  In the context of importation 
step 8, are the conclusions in Australia's IRA in respect of the probability range and distribution 
pattern for ALCM surviving and remaining with the apple fruit after on-arrival minimum border procedures (uniform distribution between 0.7 and 0.9) sufficiently supported by the available 
scientific evidence?  Are the conc lusions in Australia's IRA on this issue scientifically justified and 
reasonable?  Do these conclusions fall within a rang e that could be considered legitimate according 
to the standards of the scientific community and th e methodology applied in the IRA?  (IRA, Part B, 
p. 165;  paras. 4.344-4.349 New Zealand's FWS;  and para. 749 of Australia's FWS) 
 
Dr Cross
: 
 
666. A 600 fruit sample taken in NZ prior to export would ensure with 95% confidence that the 
maximum infestation rate of 0.5% occupied cocoons was not exceeded.  If there is a second 
mandatory independent border inspection of 600 fruit s were done then this is essentially the same as a 
total inspection of 1200 apples.  Substituting n = 1200 and using a 95% confidence value in the 
binomial formula gives the proportion of fruit as 0. 0025, i.e. 0.25% or 1 in 400.  So a second 
inspection would reduce the likelihood by a factor of 2,  giving a probability factor for this stage of 0.5 WT/DS367/11 
Page 126  
 
  not including any other mortality factors.  This is not far from the value of 0.46 given in para 3.346 of 
NZ FWS (calculated on an assumption of an infesta tion level of 0.13%) and appreciably lower than 
the mid point value of 0.9 given in importation step 8 of Australia's IRA. 
667. There appears to be a fundamental disagreement  between the parties as to whether a second 
inspection would be carried out, Australia asserting th at such an inspection would either not occur or 
would be ineffective.  This needs to be resolv ed.  The effects depend on whether or not a second 
inspection in carries out, the sample size and met hod and the efficacy of detection.  The 0.25% 
infestation level that would be detected with 95%  confidence from two 600 fruit samples is above the 
0.13% average infestation level found in the August 2005 data. 
668. Australia's evaluation of importation step 8 see ms to suggest there would only be minimum 
border procedures and that there would be no sec ond inspection, the values of 0.9 being given to 
account for possible natural mortality. 
Dr Deckers
: 
 669. The number of viable insects after the whole process of fruit preparation, storage and 
exportation is the decisive parameter that should be taken into account.  The number of cocoons on 
the fruits can be substantially different from the number of hatching insects. 
Question 114 
Please comment on the decision in Australia's IRA not to limit itself to the August 2005 data indicating the level of ALCM infestation of expor t quality New Zealand apples destined for the United 
States, on the grounds that such data did not reflect unrestricted risk but a level of importation where 
risk mitigation measures were already applied?  (IRA,  Part B, pp. 166, 172- 174, 178-183, 190-192;  
para. 755 of Australia's FWS) 
 
Dr Cross
: 
 
670. As stated above, Australia should have discarde d its original figures based on a small number 
of old spot estimates in the literature and used  the good quality August 2005 da ta.  New Zealand have 
given assurances that the fruit on wh ich the August 2005 data was based was not subject to any risk 
mitigation procedures or other procedures that would reduce the infestation rate and have stated that 
the efficacy of detection of inspections is close to 1.0. 
Dr Deckers : 
 
671. It is not clear which risk mitigation measure s were undertaken by New Zealand that should 
have influenced  the 2005 data.  Anyway these data i ndicate an infection percentage that is about 10 
times lower than the infection percentage proposed by the IRA. 
Question 115 
Please comment on whether the consideration in Au stralia's IRA of the likelihood of entry and 
establishment of ALCM through mature apple fruit from New Zealand was objective and credible, 
relying on respected and qualified scientific sources with respect to whether adult emergence of 
ALCM from diapause may take place in seasons other than spring (for example, if the cool chain is 
broken and day length and temperature replicate spring,  such as in a controlled environment like a 
supermarket or packing house, or in  specific areas of Australia).  Would this be relevant to the 
establishment of ALCM, taking into account host specificity and specific environmental requirements 
for establishment?  Is the consideration in Australi a's IRA on this issue suffic iently supported by the 
available scientific evidence?  (IRA, Part B, p. 161;  para. 4.118 of Ne w Zealand's FWS;  and 
para. 766 of Australia's FWS)  WT/DS367/11 
 Page 127 
 
 
   
Dr Cross : 
 672. Adult emergence of ALCM (which occurs afte r pupation and not immediately after diapause 
is completed by 3
rd instar larvae in cocoons) may take place in seasons other than spring if suitable 
environmental conditions occur either outdoors in summer or autumn or at any time in a controlled 
environment in a supermarket or pack house.  On average, this woul d decrease the risk of 
establishment because some adults would emerge in winter when they are unable to find a suitable 
host outdoors.  Adults emerging from fruit sold in  late autumn, winter or early spring (when 
conditions outdoors are not suitable for ALCM estab lishment) would pose no risk.  If the fruit were 
discarded in the vicinity of an apple tree, some of  the adults would have already emerged reducing the 
numbers that could emerge later when environm ent and host plant conditions were suitable for 
survival. 
Dr Deckers : 
 
673. It can be important to consider the conditions  when the adults emerge after a period of 
diapause.  To be successful the hatching process should be under conditions comparable to the 
situation of the cocoons in the soil after the dorma ncy period, where temperature and moisture will be 
important factors.  When the hatching occurs under other circumstances like in a supermarket or in a 
packing house, the chances of normal development and survival could be different from the normal 
situation. 
674. Also from the side of the host plant there shoul d be a coincidence in the development stages 
necessary for the midges to have young leaves on the host plants at the moment of hatching.  Both 
factors will strongly reduce the real infection risk. 
Question 116 
Please comment on whether the consideration in Au stralia's IRA of the likelihood of entry and 
establishment of ALCM through mature apple fruit from New Zealand was objective and credible, 
relying on respected and qualified scientific sources with  respect to whether so me ALCM larvae that 
have entered diapause may have prog ressed beyond the pre-pupal stage to the pupal stage and will be 
ready to emerge as adults as soon  as, or shortly after, the approp riate environmental triggers are 
encountered by the pupa, or whether they will necessa rily take the 13-18 days (as indicated by Barnes 
(1948)) to emerge once they have encountered appropria te environmental trigg ers?  In other words, 
is it possible for diapause in ALCM to end due to  climatic conditions and then for ALCM development 
to be completed in less time than 13-18 days?  (I RA, Part B, pp. 171 and 180;  para. 4.361 of 
New Zealand's FWS;  and paras. 772-773; 780-784; 795-797 of Australia's FWS) 
 
Dr Cross : 
 
675. This has already been answer ed in detail under Question 94 (i), the conditions for adult 
emergence of ALCM. ALCM could emerge in less than 13-18 days because the cocoons may contain 
mature pupae close to emergence.  No data has be en presented to show that  AA or CA storage will 
have killed such pupae. 
Dr Deckers : 
 
676. I think the situation is more complex than it is  described here;  the situation for development 
of 13 to 18 days can vary following the conditions of  temperature and moisture.  What is the length of 
the period of diapause and what are the determining f actors to bring this period to an end ?  Question 
is if the same factors will be av ailable when the cocoons hatch after they have been in storage for 
some months and when the fruits are exported. WT/DS367/11 
Page 128  
 
  Question 117 
Please comment on whether the consideration in Aust ralia's IRA of the likelihood of spread of ALCM 
in Australia was objective and credible, relying on respected and qualified scientific sources with 
respect to the climatic conditions su itable for the spread of ALCM.  Is  the consideration in Australia's 
IRA on this issue sufficiently supported by the avai lable scientific evidence?  (IRA, Part B, pp. 177-
180;  paras. 4.364-4.365 of New Zealand's FWS;  paras. 811-813 and 821 of Australia's FWS;  and R 
81 from New Zealand) 
 
Dr Cross
: 
 
677. Australia's IRA on this point seems objective a nd credible but, as stated in the answer to 
question 94, a weakness in the IRA was that Austra lia failed to quantify (or at least delimit) the 
geographic range and range of conditions which are necessary for ALCM est ablishment and spread, 
both in terms of temperature and rainfall and their seasonal occurrence.  The geographic and climatic limits were not established.  The distribution of AL CM in the continent of Europe, where it has long 
been present and it's range and distribution have more  or less reached equilibrium, used in conjunction 
with evidence from different regions of the American  continents, could have been used to establish 
climatic conditions that are especially favourable  to ALCM and geographi c and climatic boundary 
conditions for its existence.  There are extensive areas where apples are cultivated that are unsuitable 
for ALCM.  It is considered to be absent from ho t, dry areas of southern Europe and Israel for 
instance and in the USA it evidentl y does not occur in the southern apple growing regions of Carolina 
or Georgia though it has spread westward from New Yo rk State.  In the northern hemisphere, ALCM 
does not appear to occur at latitudes less than approxi mately 38°.  It also appears to be absent from 
areas with greater latitudes where summer rainfall is very low or absent.  It is most troublesome in 
areas with high rainfall.  A climatic analysis woul d also have given a better assessment of the likely 
impact of ALCM in different areas of Australia .  Recent hot droughty climatic conditions in SE 
Australia have been unsuitable for ALCM, though th e climate of Tasmania does appear favourable.  
However, the IRA did not assume that ALCM would spread to all areas of Australia where apples are 
grown commercially or domestically and the overall assessment is correct. 
Dr Deckers
: 
 678. The spread of the ALCM will be limited to the regions with cool temperate zone climatology 
and this aspect was maybe not sufficiently taken into  account in Australia's IRA and this could have 
over estimated the likelihood of spread.  Nevertheless there are regions in Australia with this type of 
cool temperate climatology where ALCM could spread easily. 
Question 118 
Please comment on the relative potential impact of fa ctors such as the suitab ility of local climatic 
conditions and the volume of ALCM infesti ng apples imported from New Zealand for ALCM 
establishment in the territory of a Member such as Chinese Taipei.  (Paras. 4.364-4.365 of 
New Zealand's FWS;  para. 821 of Australia's FWS) 
 
Dr Cross
: 
 
679. This question has already been partially answered in answers to Questions 107 and 117.  The 
climatic limits under which ALCM can survive need to be quantified and the climatic conditions in 
other member states such as Chinese Taipei need to be evaluated in comparison. Chinese Taipei is at a 
latitude of 25°, well sout h of the known range of ALCM in the northern hemisphere.  Australia's FWS 
para 821, states that Chinese Taipei has a subtropi cal, oceanic climate.  There are no records of 
ALCM in tropical or sub-tropical areas.  ALCM is  unlikely to establish in Chinese Taipei because the 
climate is unsuitable.  WT/DS367/11 
 Page 129 
 
 
  Dr Deckers : 
 680. The suitability of the local climatic conditions is decisive for the potential introduction of the 
ALCM into a new area and this is more important  than the volume of infested apples imported. 
Question 119 
In the context of the assessment of consequen ces of an incursion of ALCM in Australia, please 
comment on whether the reasoning and conclusions in Australia's IRA were objective and credible 
with respect to the potential fo r an increased use of insecticides,  disruption of existing pest 
management programs, increases in control meas ures and increased costs to producers.  Is the 
consideration in Australia's IRA on this issue sufficiently supported by  the available evidence?  (IRA; 
Part B, p. 185;  para. 4.371 of New Zealand 's FWS;  and paras. 839-840 of Australia's FWS) 
 
Dr Cross
: 
 681. Australia's IRA part B page 185 does not indicate that ALCM is only likely to be a significant 
pest problem in nurseries and young trees in orchards that are establishing and was deficient in this 
respect as pointed out by NZ in para 4.371 of its FWS.  However, Australia is right to point out in paras 840 of their FWS that invasive species do not necessarily behave in the same way when they are 
introduced to different parts of the world.  If AL CM were to establish in Australia with out its 
parasitoid Platygaster demades , in regions with a suitable clim ate it could be more numerous and 
damaging than it currently is in similar regions in  NZ.  However, where invasive outbreaks of ALCM 
have occurred in other countries, the grower respon se has not been to treat established orchards with 
insecticides.  In general, growers have learnt th at controlling ALCM in established orchards with 
broad spectrum pesticides is counter productive becau se of destruction of natural enemies and is not 
necessary because it does not lead to  increases in yield or quality. 
682. The establishment of ALCM in Australia could lead  to increased use of insecticides if suitable 
insecticides were available in Australia but this w ould probably be confined to nurseries and possibly 
young trees.  This would lead to marg inally increased costs to producers. 
Dr Deckers
: 
 683. Diazinon is also in Europe a standard compound in the control of the ALCM.  Problem will 
be here that in the near future there will be a ser ious reduction in the number of insecticides available 
within the IPM production method for the control of diseases like ALCM..  In Belgium the Diazinon 
is not longer available for the control of ALCM on  apple.  The fact that ALCM would need an 
insecticide treatment does not mean that there will be a disruption of the existing pest management 
program. 
Question 120 
Please comment on whether the conclu sion in Australia's IRA, that an inspection of a 600 fruit sample 
from each import lot would not achieve Australia 's ALOP for ALCM, was objective and credible, in 
light of the IRA's view that the unrestricted ri sk for ALCM is "low".  How does this alternative 
measure, proposed by New Zealand, compare to the relevant measures impos ed by Australia, namely 
(i) inspection of a 3000 fruit sample from each lot with a find resulting in mandatory treatment or 
rejection for export or (ii) treatment of all lots w ith a suitable treatment to kill ALCM?  Under what 
circumstances, if at all, could the alternative measure proposed by New Zealand achieve Australia's 
ALOP?  (IRA, Part B, pp. 4-5, 165-166 and 187- 192;  paras. 4.138, 4.513-4.523 of New Zealand's 
FWS;  paras. 734-735, 824, 954-957 1089-1105 of Aust ralia's FWS;  and R 140-141 by the Parties) 
 WT/DS367/11 
Page 130  
 
  Dr Cross
: 
 684. The unrestricted risk estimation presented in Tabl e 49 of Australia's IRA part B p 187 needs 
to be recalculated for two different importation scenarios: 
(a) Mature apple fruit free of trash, either p acked or sorted and graded bulk from New 
Zealand 
(b) Retail ready fruit which would not be handled at sensitive utility points 
685. The August 2005 infestation rate data should be  used and viability, parasitism and the time 
span of adult emergence relative to adult longevity n eed to be taken into account in the recalculation.  
The inclusion or exclusion of different utility poin ts for the two importation scenarios is crucial.  
Consideration needs to be given to the numbers of fruit that are likely to be placed or discarded within 
the flight range of a susceptible host at the relevant  utility points in formulating the risk estimates.  It 
might be found that the unrestricted risk estimates for one or both of these scenarios then falls below 
Australia's ALOP. 
686. If not, then the sample sizes required to meet Australia's ALOP should then be recalculated 
for fruit subject to fumigation and not subject to fu migation for each of the two importation scenarios.  
Note that the sample size should not be adjusted to fit the infestation rate which appears to be the case 
in the current analysis.  It should be set to meet Australia's ALOP. 
687. Until this is done, then it is inappropriate to comment on the sample si zes and the need or 
otherwise for fumigation treatment re quired to meet Australia's ALOP. 
688. The requirements for a 3000 fruit inspection or for fruit fumigation are clearly restrictive and 
alternative measures coupled with a 600 fruit insp ection would be preferable provided they met 
Australia's ALOP. 
Dr Deckers
: 
 689. The imposed measure for a chemical control of  the problem of ALCM in the New Zealand 
orchard should concentrate on the last generati ons of the ALCM.  Together with the proposed 
inspection of a 600 fruit sample after harvest,  th is could help to achieve Australia's ALOP for 
ALCM. 
Question 121 
Please comment on whether the consideration in Aust ralia's IRA of the risk associated with the 
practice of packing houses leaving orchard wholesa ler waste uncovered and exposed to the elements 
on the premises or in landfills is objective and credible , taking into account the likelihood of this 
situation occurring in packing houses in Australia.  (IRA, Part B, p. 170 (ALCM);  paras. 4.130 and 
4.419-4.421 of New Zealand's FWS;  paras. 784-785 and 898-900 of Australia's FWS;  and R 100 by Australia) 
 Dr Cross
: 
 690. The quantities and way that waste fruit is handled at the 7 orchard wholesalers is of crucial 
importance.  If large numbers (>>100) of fruit are held in proximity to or discarded at orchard wholesalers in the vicinity of susceptible apple trees then the risk of establishment is clearly high.  
The risk would be considerably reduced, perhaps e liminated, if the fruit were enclosed so the midge 
adults could not escape.  WT/DS367/11 
 Page 131 
 
 
  Dr Deckers : 
 691. When fruit waste should remain uncovered and ex posed for a short time, the ALCM will not 
have got the opportunity to hatch from the cocoon b ecause this step will need more time (days) after 
coming out of the storage room.  A professional fruit packing station will not leave fruit waste 
uncovered for a long period. 
Question 122 
Does Australia's IRA provide an objective and coheren t assessment of the likelihood and implications 
of New Zealand apples being repacked at rural packi ng houses in close proximity to orchards, when 
assessing the risks related to fire blight, European  canker and ALCM?  Was such assessment made 
with proper methodological rigour?  (Para. 4.418 of New Zealand's FWS;  and R 99 by Australia) 
 
Dr Cross
: 
 692. Australia's IRA did provide an objective and c oherent assessment with respect to "apples free 
from trash either packed or sorted and graded bulk from New Zealand" but appears it did not consider 
the case of retail ready fruit.  It took into acc ount two scenarios of different amounts of fruit being 
handled by the orchard pack house, 70-100% versus 0.1-5%.  This lead to very large (33 fold) 
differences in the estimates of the numbers of infested apples being handles at the orchard wholesaler utility points (Tables 42 and 43) which resulted in th e estimates of the partial probabilities of entry, 
establishment and spread which are high for the orchard wholesalers (Tables 44 and 45).  However, if 
fruit were supplied from New Zealand "retail ready" or  "just in time", then it seems most unlikely that 
any fruit would be returned to the orchard whol esalers for repacking.  The IRA needs to be 
recalculated with respect to this scenario. 
Dr Deckers
: 
 
693. I don't see the necessity for repacking the fruit when New Zealand exports the apples retail-
ready.  The waste will thus be for the majority in  the New Zealand packing house.  Australia describes 
the risk in detail in the two different scenario's wi th only a few apples be repacked or with many 
apples repacked.  But this risk described in th e IRA doesn't look to correspond with the reality. 
Dr Sgrillo : 
 
694. The Australia's IRA considers two extremes scenarios:  a) from 70% to 100% of apples being 
repacked at rural packing houses and  b) from 0.1% to 5% of apples being repacked at rural packing 
houses.82 
695. The scenarios have a large effect in the pred icted number of infected fruit imported weekly, 
as is shown in IRA's Tables 42 and 43 (the data ar e in the first and second lines, respectively, of the 
two first rows of the tables).83 
696. This data were used by experts, together w ith other pieces of information, to estimate the 
partial probability of entry, establishment and spread as stated by IRA: 
These estimates are based on expert opinion  taking into account the sequence of 
events for successful transfer of the pest to a susceptible host, the estimated numbers 
of infested apples at each utility point , the availability and susceptibility of hosts at 
                                                      
82 (footnote original ) IRA p. 172. 
83 (footnote original ) IRA pp. 173-174. WT/DS367/11 
Page 132  
 
  each utility point, information relevant to est ablishment and spread of the pest and all 
relevant information provided by stakeholders.
84 
697. However, IRA is not clear in explaining how the estimated numbers of infested apples were 
used to estimate the partial probability of entry,  establishment and spread.  There are no specific 
estimates for each of the two scenarios, as can be seen in IRA's Table 44 and 4585.  It seems that the 
differences in the estimated numbers of infested a pples had not generated any difference in the partial 
probability of entry. 
Question 123 
Please comment on whether, from a technical persp ective and as described in Australia's IRA, the 17 
specific measures that have been challenged by New Zealand can be distinguished  as either measures 
active in risk reduction, or measures designed to im plement or support active measures.  (R 14-26 by 
the Parties) 
 
Dr Deckers : 
 
698. I don't think it make sense to split up the speci fic measures in measures active in risk 
reduction and measures designed to implement or support active measures.  All measures aim to reduce the risk for the different problems concerned. 
V. RISK ASSESSMENT 
Question 124 
Please comment on whether Australia's IRA takes into  account internationally accepted standards or 
guidelines from the IPPC in applying a semi-qu antitative methodology.  (Paras. 4.161-4.167 of 
New Zealand's FWS;  and paras. 288-294 of Australia's FWS) 
 
Dr Latorre
: 
 
699. Australia's IRA has taken into account interna tionally accepted standards and guidelines from 
the IPPC in applying the semiquantitative methodol ogy.  However, the likelihood values and midpoint 
values used for the semiquantitative analysis (Table 12, AUS-2BA, p. 43) should be validated before 
acceptance. 
Dr Schrader:  
 
700. Pest risk can be carried out with quantitative or  qualitative data, a combination of both is also 
possible.  The approach depends on the situation,  different approaches could be appropriate under 
different circumstances – this depends also on the quality and quantity of available data.  Up to now, 
there are no standard definitions of quantitative or  qualitative pest risk assessment provided by the 
IPPC.  So far, these terms are used differently in different contexts by different Regional and National 
Plant Protection Organisations. 
701. ISPM No. 11 states under 2.2.4 (Conclusion on th e probability of introduction and spread):  
"The overall probability of introduc tion should be expressed in terms most suitable for the data, the 
methods used for analysis, and the intended audien ce.  This may be quantitative or qualitative, since 
either output is in any case the result of a combination of both quantitative and qualitative 
information.  The probability of introduction may be expressed as a comparison with that obtained 
from PRAs on other pests."  Under 2.3 (Assessment of potential economic consequences), it is stated 
                                                      
84 (footnote original ) IRA p. 178. 
85 (footnote original ) IRA p. 179.  WT/DS367/11 
 Page 133 
 
 
  that:  "Requirements described in this step indicat e what information relative to the pest and its 
potential host plants should be assemb led, and suggest levels of economic  analysis that may be carried 
out using that information in order to assess all the effects of the pest, i.e. the potential economic 
consequences.  Wherever appropriate, quantitative da ta that will provide monetary values should be 
obtained.  Qualitative data may also be used.  Fu rther, under 2.3.2.3 (Analytical techniques):  "The 
use of analytical techniques is often limited by lack  of data, by uncertainties in the data, and by the 
fact that for certain effects only qualitative in formation can be provided."  and 2.3.2.4 (Non-
commercial and environmental consequences):  "If quantitative measurement of such consequences is 
not feasible, qualitative information about the conse quences may be provided.  An explanation of how 
this information has been incorporated into d ecisions should also be provided."  Also 2.3.3 
(Conclusion of the assessment of economic consequen ces):  "Wherever appropriate, the output of the 
assessment of economic consequences d escribed in this step should be in terms of a monetary value.  
The economic consequences can also be expr essed qualitatively or using quantitative measures 
without monetary terms.  Sources of information,  assumptions and methods of analysis should be 
clearly specified."  as well as 2.5 (Conclusion of the pest risk assessment stage):  "[…] A quantitative 
or qualitative estimate of the probability of introdu ction of a pest or pests, and a corresponding 
quantitative or qualitative estimate of economic  consequences (including environmental 
consequences), have been obtained and documented or an overall rating could have been assigned" 
refer to both qualitative an d quantitative estimates.  A pest risk assessment/analysis is in most cases 
based on qualitative approaches and expert judgment, but  it is essential that this is explained and made 
transparent.  The use of modelling is also possible.   The important point is, that the model used is 
appropriate and applied in an  adequate and correct way. 
Dr Sgrillo : 
 702. The International Standards of Phytosanitary Measures (ISPM) of the IPPC do not make 
reference to "semi-quan titative" methodology. 
703. However the semi-quantitative a pproach is described in the IPPC pest risk analysis training 
course-Participant Manual as follows:  "A semi-quantitative pest  risk assessment combines elements 
of both quantitative and qualitative assessments, ad ding precision using quantitative methods where 
these are applicable, and incorporating qualitative methods for those parts of the assessment where 
data is not available or the same degree of precision is not required."
86 
704. There are no international guidelines for devel opment of semi-quantitative models in Plant 
Protection.  A number of different methodologies c ould be applied, under the denomination of "semi-
quantitative".  The Australia's IRA is  based in the development of a quantitative stochastic model that 
relies on repeated random sampling from statistical distributions (Monte Carlo method).  The values of the parameters of the distributions were cho sen from qualitative likelihoods.  The numeric results 
of the simulations were then translated to qualitative terms. 
705. In quantitative modeling the statistical distri butions and the corresponding parameters are 
derived from sampling of the real world.  The semi-quantitative methodology used by IRA could 
introduce bias in the model because the parameters and the shapes of the distributions are mostly 
based in guesses and not derived from sampling.  Assigning numbers to subjective estimation does 
not result, necessarily, in a more objective assessment. 
706. It is not possible to evaluate the potential bi as that each step could introduce in the model 
because the IRA does not presen t the sensitivity analysis. 
                                                     
 
86 (footnote original ) Reference 02_FAO/IPPC- 2007. IPPC Pest risk analysis training course-
Participant Manual WT/DS367/11 
Page 134  
 
  Question 125 
In the light of internationally recognised and accep ted practice and standards for risk assessment in 
horticultural products that are traded internatio nally, does a proper risk  assessment need only 
evaluate measures that reduce or otherwise manag e risk?  Can or should risk assessments also 
evaluate or consider measures that do not, by themselves, have the objective of reducing risks?  
(Paras. 855-859 of Australia's FWS;  para. 53 of th e United States' Third Party submission;  and R 23 
by the Australia) 
 
Dr Latorre
: 
 
707. To my understanding, risk assessment analysis  should only consider measures that are 
directly related to reducing the risk of entrance, es tablishment and spread of a new pest or disease in a 
new geographical area.  However, the method of p est risk assessment can vary according to the 
circumstances, with other measures used when appropriate. 
Dr Schrader:  
 
708. The SPS-Agreement defines risk assessment  in Annex A as "the evaluation of the likelihood 
of entry, establishment or spread of a pest or disease within the territory of an importing Member 
according to the sanitary or phytosanitary measures which might be applied, and of the associated 
potential biological and economic consequences […]" .  Sanitary or phytosanitary measures are 
defined in Annex A as "Any measure applied:  (a) to  protect animal or plant life or health within the 
territory of the Member from risks arising from the entry, establishment or spread of pests, diseases, 
disease-carrying organisms or disease-causing organisms;  […]Sanitary or phytosanitary measures include all relevant laws, decrees, regulations, re quirements and procedures including, inter alia, end 
product criteria;  processes and production methods;  testing, inspection, certification and approval 
procedures;  quarantine treatments including relevant  requirements associated with the transport of 
animals or plants, or with the materials necessary for their survival during transport;  provisions on 
relevant statistical methods, sampling procedures a nd methods of risk assessment;  and packaging and 
labelling requirements directly related to food safety." 
709. The IPPC (1997) and ISPM No. 5 separate ma nagement measures from risk assessment.  
According to the IPPC definitions, pest risk assessment
 is the "evaluation of the probability of the 
introduction and spread of a pest and the magnitude of the associated potential economic 
consequences (see Glossary Supplement No. 2) [FAO,  1995; revised ISPM No. 11, 2001; ISPM No. 
2, 2007]", whereas pest risk management  is the "evaluation and selecti on of options to reduce the risk  
of introduction and spread of a pest [FAO, 1995; revised ISPM No. 11, 2001]" 
710. Both are subsumed under the definition of pest risk analysis , which is defined as "the process 
of evaluating biological or other scientific and econom ic evidence to determine whether an organism 
is a pest, whether it should be regulated, and the st rength of any phytosanitary measures to be taken 
against it [FAO, 1995; revised IPPC, 1997; ISPM No. 2, 2007]". 
711. In ISPM No. 11, stage 3, Risk Management, it is outlined that "the conclusions from pest risk 
assessment are used to decide whether risk manageme nt is required and the strength of measures to be 
used.  Since zero-risk is not a reasonable option, the guiding principle for risk management should be 
to manage risk to achieve the required degree of safet y that can be justified and is feasible within the 
limits of available options and resources.  Pest risk management (in the analytical sense) is the process 
of identifying ways to react to a perceived risk, evaluating the efficacy of these actions, and 
identifying the most appropriate options." 
712. ISPM No. 14 (systems approach see below, answ er to question 140) requires the evaluation of 
the efficacy of measures, which includes both independent and dependent measures.  WT/DS367/11 
 Page 135 
 
 
  713. According to my understanding, all potential measures that are proposed for managing the 
risk, either principal or designed to implement the principal measures, should be evaluated in a proper 
pest risk analysis.  This is also necessary for technical justification ("justified on the basis of 
conclusions reached by using an appropriate pest  risk analysis or, where applicable, another 
comparable examination and evaluation of av ailable scientific information", IPPC 1997). 
Dr Sgrillo : 
 714. According to the IPPC it should be recognized first that only measures that are necessary to 
prevent the introduction and spread of quarantine pests are allowed to be required by the importing country, as the Principle "Necessity" of the IPPC states: 
"Contracting parties may apply phytosanitary measures only where such measures are 
necessary to prevent the introduction and/or spr ead of quarantine pests, or to limit the 
economic impact of regulated non-quarantine p ests.  In this regard, the IPPC provides 
that:  "Contracting parties shall not, under their phytosanitary legislation, take any of 
the measures specified in ... unless su ch measures are made necessary by 
phytosanitary considerations ... "  (Article VII.2a).  Article VI.1b states that 
"Contracting parties may require phytosan itary measures for quarantine pests and 
regulated non-quarantine pests, provided that such measures are …limited to what is  
necessary to protect plant health… "."
87 
715. Secondly all the measures required shall be assessed  and technically justified, as the Principle 
"Technical justification" of the IPPC, provides: 
"Contracting parties shall technically justify phytosanitary measures "...on the basis 
of conclusions reached by using an appr opriate pest risk analysis or, where 
applicable, another comparable examinati on and evaluation of available scientific 
information."  (Article II.1).  In this regard, the IPPC provides that "Contracting 
parties shall not, under their phytosanitary legislation, take any of the measures 
specified in paragraph 1 of this Article (VII) unless such measures ... are technically 
justified."  (Article VII.2a)."88 
716. The IPPC recognizes also "Operational principl es" that are related to the establishment, 
implementation and monitoring of phytosanitary measures, and to the administration of official phytosanitary systems.  The recognized Operational Pr inciples are:  "pest risk analysis, pest listing, 
recognition of pest free areas and areas of low pest prevalence, official control for regulated pests, 
systems approach, surveillance, pest reporting, phyt osanitary certification, phytosanitary integrity and 
security of consignments, prompt action, emergency measures, provision of a National Plant Protection Organization, dispute settlement, avoidance of undue delays, notification of non-
compliance, information exchange and technical assistance."
89 
717. The conclusion is that only measures neces sary to prevent the introduction/spread of 
quarantine pests may be established and that each of these measures should be assessed and justified. 
                                                      
87 (footnote original ) Reference 10:  IPPC, ISPM No. 1:  Phytosanitary principles for the protection of 
plants and the application of phytosanitary  measures in international trade, 2006. 
88 Ibidem. 
89 Ibidem. WT/DS367/11 
Page 136  
 
  Question 126 
Do internationally recognised and accepted practice and standards for risk assessment, such as the 
ISPMs, provide any guidance as to who may participat e in a risk assessment panel?  (Para. 4.468 of 
New Zealand's FWS;  and R 89-91 by Australia) 
 Dr Latorre
: 
 718. I am not aware of any document providing guidance as to who may participate in a risk 
assessment panel.  It is possible that this should be in accordance with the Commission on 
Phytosanitary Measures (IPPC, Art. XI).  In my opini on, specialists should be included in the panel to 
analyse the information and make final conclusions .  However, this does not prevent requesting the 
opinions of other people, including farmers, hor ticulturists, mathematicians, biometricians or 
politicians, when appropriate. 
Dr Schrader:
 
 
719. According to the International Plant Prot ection Convention, National Plant Protection 
Organisations are responsible for the conduct of pest risk analyses (Article IV 2 f). ISPM No. 2 refers 
to this article on page 7:  "Article IV.2f states that the responsibilities of the National Plant Protection 
Organization (NPPO) include " the conduct of pest risk analyses ".  No further guidance is given here.  
ISPM 11 states under 2.3.2.3 (Analytical techniques) th at there are analytical techniques which can be 
used in consultation with experts in economics to  make a more detailed analysis of the potential 
economic effects of a quarantine pest.  In addition,  ISPM No. 11 states under 1.1.1:  "A list of pests 
likely to be associated with the pathway (e.g. ca rried by the commodity) may be generated by any 
combination of official sources, databases, scientific  and other literature, or expert consultation".  
Both standards refer to "expert judgment". 
720. Common practice is that ad hoc  experts are included in risk assessment panels which may not 
be employed by an NPPO.  This is e.g. the case in the Expert Working Groups conducting PRAs that 
are organised and lead by the European Plant Pr otection Organisation (EPPO).  The European Food 
Safety Authority (EFSA), which reviews and also conducts PRAs, has established a plant health panel 
that is doing this work, and most of the members ar e not employed by an NPPO, the same is true for 
ad hoc  experts involved in specific cases.  However,  EFSA requests from any expert involved in the 
work a declaration of interest.  If an expert has to declare an inter est, he/she may be excluded from the 
work or parts of it. 
Dr Sgrillo : 
 721. There is international no guidance on who may participate in a risk assessment panel. 
Question 127 
Please comment on whether it would be a legitimate methodological approach for a risk assessor to 
assess the unrestricted risk in th e first instance, and then assess th e extent to which potential risk 
management measures could mitigate that risk.  Likewise, would it be a legitimate methodological 
approach for a risk assessor to only assess the unrest ricted risk, without considering the extent to 
which potential risk management measures could mitigate that risk?  (IRA, Part B, pp. 23, 40-41, 44;  
and paras. 824 and 902 of Australia's FWS) 
 
Dr Latorre
: 
 722. There is not a single accepted methodology to  assess the risk of entrance, establishment and 
spread of a pest or disease.  It is legitimate to asse ss firstly the unrestricted risk and then following the  WT/DS367/11 
 Page 137 
 
 
  same or similar methodology to assess measures to mitig ate the risk.  It would also be acceptable to 
assess only the unrestricted risk, if appropriate. 
Dr Schrader:  
 723. Pest risk analysis, as is outlined in ISPM 2 and 11, comprises risk assessment and risk 
management.  The definition of pest risk anal ysis as provided in ISPM No. 5 (Glossary of 
Phytosanitary Terms) is as follows:  "The process  of evaluating biological or other scientific and 
economic evidence to determine whether an organism  is a pest, whether it should be regulated, and 
the strength of any phytosanitary measures to be  taken against it [FAO, 1995; revised IPPC, 1997; 
ISPM No. 2, 2007]".  To assess the unrestricted risk in the first instance, and then assess the extent to 
which potential risk management measures could mitigate that risk is therefore a legitimate 
methodological approach.  It is also legitimate to only assess the unrestricted risk in accordance with 
the definition for pest ri sk assessment (see also an swer to question 125), however this would not make 
any sense with regard to the purpose of a pest risk analysis/import risk analysis when an unacceptable 
risk is identified in this assessment.  In case, the assessment reveals that the (unrestricted) risk with 
regard to introduction and spread of the pest is acc eptable however, the consideration of potential risk 
management measures is not necessary. 
Dr Sgrillo
: 
 724. ISPM 11
90 describes the methodology that sha ll be used in the PRA process: 
"Stage 1 (initiation) - The aim of the initiation stage is to identify the pest(s) and 
pathways which are of quarantine concern a nd should be considered for risk analysis 
in relation to the identified PRA area. 
Stage 2 (Pest risk assessment) - The process for pest risk assessment can be broadly 
divided into three interrelated steps: 
(a) Pest categorization 
(b) Assessment of the probability of introduction and spread 
(c) Assessment of potential economic conseque nces (including environmental impacts). 
Stage 3: Pest Risk Management - The conclu sions from pest risk assessment are used 
to decide whether risk management is re quired and the strength of measures to be 
used.  Since zero-risk is not a reasonable option, the guiding principle for risk management should be to manage risk to achieve the required degree of safety that 
can be justified and is feasible within the limits of available options and resources.  
Pest risk management (in the analytical sen se) is the process of identifying ways to 
react to a perceived risk, evaluating the efficacy of these actions, and identifying the most appropriate options.  The uncertain ty noted in the assessments of economic 
consequences and probability of introducti on should also be considered and included 
in the selection of a pest management option". 
725. Therefore it is a legitimate methodological approach for a risk assessor to assess the 
unrestricted risk in the first instance, and then assess the extent to which potential risk management 
measures could mitigate that risk. 
                                                     
 
90 (footnote original ) Exhibit AUS-6:  IPPC, ISPM No. 11:  Pest risk analysis for quarantine pests 
including analysis of environmental risks and living modified organisms, 2004. WT/DS367/11 
Page 138  
 
  726. It would not be a legitimate methodological approach to only assess the unrestricted risk, 
without considering the extent to which potential ri sk management measures could mitigate that risk 
(to assess the necessary strength of measures). 
Question 128 
What factors might be relevant in deciding wheth er to adopt a qualitative, a semi-quantitative, or a 
quantitative methodology for a particular risk assessment?  
Dr Sgrillo
: 
 727. See also question 124. 
728. When reliable specific numeric data are available and more precision is required then 
quantitative model shall be used.  The main advantag e of this approach is that it generates objective 
and reproducible conclusions to satisfy the tec hnical justification for phytosanitary measures. 
729. When reliable numeric data are not availa ble then qualitative methods will be used. 
730. According to the OIE the semi-quantitativ e method would not be recommended because: 
"However, a number of significant problems may arise from adopting a semi-
quantitative approach in an import risk analysis.  It is some times employed as a means of combining various qualitative estimates, by assigning numbers to them, to produce a summary measure or to priorize risks.  The numbers may be in a form of probabilities ranges or scores, which may be weighted before combined by addition, multiplication, etc.  The numbers, ranges, weights and methods of combination 
chosen are usually quite arbitrary and need careful justification to ensure 
transparency.  It should be recognised that numbers assigned to categories cannot be manipulated mathematically and statistically.  It is impossible to assign precise numbers unless a quantitative assessment h as already been carried out.  Semi-
quantitative assessments often give a mi sleading impression of objectivity and 
precision and may not adequately reflect rela tivities, which can lead to inconsistent 
outcomes.  Assigning numbers to subjective estimates does not result in a more objective assessment, particularly when th e numbers chosen and their method of 
combination are arbitrary.  Semi-quantitativ e methods will rarely offer any advantage 
over a well researched, transparent, peer reviewed qualitative assessment".
91 
Does Australia's IRA provide an objective and coh erent explanation for the fact that it uses a semi-
quantitative methodology in this case for only the second time for a plant product?  
Dr Sgrillo
: 
 731. There is no such an explanation for the use of  a semi-quantitative approach.  Australia has 
noted, however, that SPS Agreement does not prescr ibe a particular risk assessment methodology.
92 
What is the relevance, if any, of the Senate Inqu iry referred to by New Zealand in its opening 
statement?  (Para. 110 of Australia's FWS;  para.  73 of New Zealand's opening statement;  and R 92-
94 by the Parties) 
                                                      
91 (footnote original ) Exhibit NZ-47:  OIE (2004a), Handbook on Import Risk Analysis for Animals 
and Animal Products Volume 1:  Introduction and Qualitative Risk Assessment, World Organization for Animal Health. pp. 27-28. 
92 (footnote original ) R 93 by Australia.  WT/DS367/11 
 Page 139 
 
 
   
Dr Latorre (Response to whole question) : 
 732. Qualitative, semi-quantitative, or quantitativ e methodologies can be appropriate.  The 
decision will depend on the pests or diseases under stud y and on the quantitative data available in the 
literature.  However, to my understanding, Austra lia's IRA does not provide a technical explanation 
for the use of a semi-quantitative a pproach, except to say that this procedure apparently facilitates the 
interpretation by stakeholders and reinforces object ivity and transparency (AUS-2BA p. 11).  The 
decision to use a semi-quantitative methodology to assess the risks must be taken by experts.  
Therefore any intervention of the Senate in this  regards, if ever happens, would be improper and 
should be clarified. 
Dr Schrader (Response to whole question):
 
 733. In accordance with ISPM 11, PRAs can be  qualitative or quantitative (or include both 
methodologies).  This is mostly depending on available data and information.  In  most cases, available 
information is in such a way, that a (fully) qua ntitative risk assessment is not possible (see also 
answer to question 124). 
Question 129 
Does Australia's IRA provide an objective and coherent explanation for the fact that it applies a semi-quantitative methodology to establish the likelihood of the entry, establishment and spread of certain pests, including the three at issue in this disput e, while applying a qualitative methodology to some 
other pests?  (Para. 110 of Australia's FWS;  par a. 56 of the United States' Third Party submission;  
para. 73 of New Zealand's opening statement;  and R 92-94 by the Parties) 
 
Dr Latorre
: 
 
734. To my understanding, Australia's IRA does not provide an explanation for the fact that it uses 
a semi-quantitative approach to est ablish the likelihood of the entry, establishment and spread of 
certain pests, while it uses a qualitative methodology in other cases. 
Dr Sgrillo : 
 735. Australia informs that the choice of methodol ogy "was based on the available information 
about the various pests, the nature of the pests themselves, the scientific literature including other 
relevant risk analyses, the need  for transparency and consistenc y, and the complexity of the 
pathway".
93 
736. However, in most cases the data and specific info rmation needed were not available.  So the 
IRA team has chosen the distributions and thei r parameters through guesses.  The guesses represent 
hypotheses about the system, and these hypotheses we re not validated because the necessary actual 
data were not available. 
737. Australia has not explained, also, how the natu re of the pests could favor the choice of the 
semi-quantitative method. 
Question 130 
Does Australia's IRA provide an objective and coheren t assessment of the likelihood and implications 
of New Zealand apples being repacked at rural packi ng houses in close proximity to orchards, when 
                                                      
93 (footnote original ) R 94 by Australia. WT/DS367/11 
Page 140  
 
  assessing the risks related to fire blight, European  canker and ALCM?  Was such assessment made 
with proper methodological rigour?  (Para. 4.418 of New Zealand's FWS;  and R 99 by Australia) 
 
Dr Latorre
: 
 
738. To my understanding, this was an estimation based on general knowledge of the biology of 
N. Galligena , considering two scenarios with low (0.1-5%) and high (70-100%) proportions, 
respectively, of the fruit being repacked in orchard packing houses.  Probability values were 
estimated.  However, the rationale involved in these estimations is not clear.  For instance, probability 
from 0.7 to 1.0 was assigned in the highest scenario.  Probability of one would mean that if a single 
apple fruit had visible sporulating lesions of N. Galligena  and was repacked (or discharged?) at the 
packing houses, N. Galligena  would invariably spread to the nearest apple trees.  If so, this is hard to 
believe.  If apples were repacked at rural packing houses in close proximity to the orchards, I would 
expect that chances of dispersal and establishment of N. Galligena  to increase slightly.  Knowing the 
biology of N. Galligena , there are many factors (primarily environmental), that would have to concur 
in order to successfully disseminate N. Galligena  under these circumstances.  Mitigation 
measurements can be proposed at this step. 
Dr Sgrillo : 
 739. For the fire blight and European canker see Response 46.  For ALCM see Response 122. 
Question 131 
Please comment on the applicability of OIE guide lines when referring to plant related risks.  
(R 102-103 by the Parties) 
 
Dr Latorre
: 
 
740. In biology, there are general principles that can be applied universally, independent of the 
nature of the organisms.  Therefore, the use of  OIE guidelines (Handbook on Import Risk Analysis for 
Animals and Animal Products) seems appropriate in  the context to which New Zealand applied it. 
Dr Schrader:  
 741. For plant health issues, clearly the Intern ational Plant Protection Organisation and its 
standards are the competent and responsible frame work.  OIE guidelines deal with animal diseases, 
where situations may be quite different.  IPPC st andards are concretely adopted for plant health 
issues.  This is also specified in the SPS agreement in Annex A, which states under (c) that with 
regard to plant health, "the international sta ndards, guidelines and recommendations developed under 
the auspices of the Secretariat of the Internationa l Plant Protection Convention in cooperation with 
regional organizations operating within the frame work of the International Plant Protection 
Convention" are relevant. 
Dr Sgrillo
: 
 742. The Codex Alimentarius Commission , the International Office of Epizootics (OIE)  and the 
International Plant Protection Convention (IPPC)  are recognised by the SPS agreement as the 
international organization respons ible for developing standards,  guidelines and recommendations for 
food safety, animal health and zoonoses and for plant health, respectively.
94  These organizations 
share the same scientific principles and concepts.  The general  concepts, procedures and methods 
                                                      
94 (footnote original ) SPS Agreement, Annex A, pg 77.  WT/DS367/11 
 Page 141 
 
 
  based in scientific principles, including risk analys is, developed by these Organizations have mutual 
applicability. 
Question 132 
Does Australia's IRA provide an objective and coherent explanation regarding the period of time for completion of the IRA? 
 
Dr Sgrillo
: 
 743. Australia's IRA provides background informa tion on the development of the IRA including 
on the previous risk analysis starting in 1996.
95  A timeline for the current  risk analysis is also 
presented In Annex 1 of the Australia's First Written Submission.96 
744. The development of the current IRA began in February 1999 and the final IRA was released 
in November 2006, after almost eight years.  Th ree public consultation peri ods were open (11/2000, 
02/2004 and 12/2005).97 
745. However the previous risk analysis, that be gan in 1996 and was released in 1998, required 
only two years to be developed.  To devel op the previous risk analysis IRA states: 
"AQIS reviewed the available scientific lite rature, sought opinion from stakeholders, 
considered all the material provided du ring the consultation process and followed 
ISPM No. 2: Part 1 – Import regulations: Gu idelines for  pest risk analysis (FAO, 
1996a)".98 
746. Consequently much of the data and informati on necessary for the development of the current 
IRA had already been revised and was available wh en the development of the current IRA began. 
747. There are no explanation regarding the di fference on the necessary time to develop the 
previous IRA (two years) and the time spent in th e development of the current IRA (eight years). 
Please also provide information on comparable pl ant protection IRAs that  were concluded in a 
significantly shorter or longer period of time th an this IRA, and the factors that might have 
determined the time necessa ry for completing such IRAs. 
 
Dr Sgrillo : 
 748. Australia provide the information that the previous IRA was developed in two years.
99 
Please comment on the experience of the United St ates referenced in its Third Party submission.  
(Para. 92 of the United States' Third Party submission;  and R 142 and 145 by Australia)  
Dr Sgrillo
: 
 749. Australia inform that during this period (1 999-2008) it has completed five import risk 
analyses (namely, table grapes, bulk maize, swee t corn, finfish and pig meat) according to the 
priorities identified by the United States and it has also completed eight import policy reviews that 
                                                     
 
95 (footnote original ) IRA pp. 7-8. 
96 (footnote original ) Australia FWS, Annex1, pp. 332-336. 
97 Ibidem. 
98 (footnote original ) IRA p. 8. 
99 (footnote original ) IRA p. 7-8. WT/DS367/11 
Page 142  
 
  improved existing access for United States' products.
100  These facts makes the delay (for the 
development of the IRA for USA's apples) appears less severe. 
Dr Latorre (Response to whole question) : 
 750. The period of time allowed for completion of the import risk analyses (IRA) was too long 
(1999 to 2007).  An acceptable explanation regardi ng the time taken for completion of this analysis 
was not presented.  I have no information regardi ng the time taken for other IRA and I am not aware 
of the factors that have determined the time necessary for completion of other IRAs. 
751. The assertions made by the United States, although external to the present dispute, are another 
example of the unjustified slowness observed by the Australian IRA team in undertaking and 
completing the IRA.  This is suggesting that the overall procedures should be reviewed in the future. 
Dr Schrader (Response to whole question):
 
 752. I can not adequately answer this question.  Howe ver, I would like to refer to the IPPC and to 
ISPMs Nos. 1, 2, and 24 that deal with the avoidance of undue delay: 
Article VII.2h IPPC: 
Contracting parties shall, as conditions change, and as new facts become available, 
ensure that phytosanitary measures are promptly modified or removed if found to be unnecessary. 
ISPM 1:  2.14 (Avoidance of undue delays ):  When a contracting party requests 
another contracting party to establish, m odify or remove phytosanitary measures, 
when conditions have changed or new fact s have become available, this request 
should be considered without undue delay.   Associated procedures, which include, 
but are not limited to, pest risk analysis , recognition of pest free areas or recognition 
of equivalence, should also be performed promptly. 
ISPM No. 2:  3.6 (Avoidance of undue delay):  Where other contracting parties are 
directly affected, the NPPO should, on request, supply information about the 
completion of individual analyses, and if possible the anticipated time frame, taking into account avoidance of undue delay (secti on 2.14 of ISPM No. 1:  Phytosanitary 
principles for the protection of plants and the application of phytosanitary measures in international trade, 2006). 
ISPM No. 24:  2.7 (Timeliness):  Contrac ting parties should end eavour to determine 
the equivalence of phytosanitary measures and to resolve any differences without 
undue delays.  And Annex 1, step 7:  If equivalence is recognized by the importing 
contracting party, implementation should be  achieved by the prompt amendment of 
the import regulations and any associated procedures of the importing contracting party.  The amendments should be communi cated in accordance with Article VII.2b 
of the IPPC (1997). 
Question 133 
Does Australia's IRA provide objective and coherent explanations for the probability intervals assigned under the IRA to the qualitative descripti ons of events, which are based on ranges of pre-
                                                     
 
100 (footnote original ) R 142 by Australia.  WT/DS367/11 
 Page 143 
 
 
  determined probability values set out in Table 12 at p.  43 of Part B of the IRA, when applied on a per 
apple basis? 
 
Dr Sgrillo : 
 
753. The methodology is described in the Australia's Guidelines for Import Risk Analyses.101 
"... to divide explicitly the 0–1 interval in to a small number of mutually exclusive 
categories, or 'probability intervals'.  Th ese categories may subsequently be correlated 
with an equal number of descriptors..." 
754. The descriptors are those presented in table 15 of the  Guidelines for Import Risk Analyses 
(high, moderate, low, very low,  extremely low and negligible).102 
755. The probability interval seems to have been  arbitrarily chosen to represent the qualitative 
descriptors.  There are no perceived criteria for assigning probabilities intervals to the qualitative 
scale.  No mathematical relationship between th e categories was found, as presented in Figure 2. 
Figure 2. Relationship between the probab ility intervals (ranges) and the qualitative 
descriptors. 
 
 
Are those probability intervals based on a leg itimate methodological approach and supported by 
sufficient scientific evidence? 
 Dr Sgrillo
: 
 756. The IRA uses six categories, but could have been five, seven or eight categories.  The values 
used for the ranges of probabilities seem to have been arbitrarily settled. 
                                                     
 
101 (footnote original ) Reference 07:  Biosecurity Australia.  Gu idelines for import risk analysis.  Draft 
September 2001. p. 86. 
102 (footnote original ) Reference 07:  Biosecurity Australia.  Gu idelines for import risk analysis.  Draft 
September 2001. p. 84. WT/DS367/11 
Page 144  
 
  (iii)
 Are they in line with internationally accep ted risk assessment standards and methodology? 
 
Dr Sgrillo : 
 757. The semi-quantitative methodology is not mentio ned in the international standards of the 
IPPC and is not supported by the OIE:  "Semi-qua ntitative methods will rarely offer any advantage 
over a well researched, transparent, peer reviewed qualitative assessment"
103 (see Question 128). 
Does the IRA provide objective and coherent explanati ons for assigning a range of 0 to 1 x 10E-6, 
regarding the probability of a "negligible" event when applied on a per apple basis? 
 Dr Sgrillo
: 
 758. IRA defines the "negligible" category as " The event would almost certainly not occur ".
104  
The range of probabilities assigned to this event is 0 to 1E-6.  This choice is arbitrary because other 
ranges, as 0 to 1E-9 or 2E-6, could also be used, after adjustment of the remaining ranges, without 
violating any scientific principle. 
759. The likelihood of 1E-6 corresponds to an o ccurrence in each 1.000.000 units, what seems to 
be negligible.  However in stochastic pest risk  models (see question 137), the number of expected 
occurrences is found multiplying the probability of  occurrence by the number of units in the 
population. 
760. Figure 3 shows, in logarithmic scale, the numbe r of fruits that corresponds to each likelihood 
category, considering a population of 200.000.000 fruits. 
Figure 3. Number of fruits in each likelihood category, from a total of 200.000.000 
fruits. 
 
 
                                                      
103 (footnote original ) Exhibit NZ-47:  OIE (2004a), Handbook on Import Risk Analysis for Animals 
and Animal Products Volume 1:  Introduction and Qualitative Risk Assessment, World Organization for Animal 
Health. p. 28. 
104 (footnote original ) Reference 07:  Biosecurity Australia.  Gu idelines for import risk analysis.  Draft 
September 2001.  p. 86.  WT/DS367/11 
 Page 145 
 
 
  761. Note that the "very low" category corresponds to " The event would be very unlikely to occur ";  
the "extremely low" category is described as " The event would be extremely unlikely to occur " and the 
"negligible" category is " The event would almost certainly not occur ".105 
762. There is a difference between likelihood per unit  and number of expected occurrences  in the 
population.  The numeric probabilities representing th e qualitative descriptors in the IRA are to be 
interpreted in a per unit  basis.  However they have to reflect  the concept of each category (negligible, 
low, etc) also in populational terms . 
763. It can be noted that, in the lower part of the categories, some distortion become evident.  The 
"very low" category contains up to 10,000,000 fruits, the "extremely low" category contains up to 200,000 fruit and the "negligible" category 200 fruits. 
764. In the phytosanitary context "negligible" should represent, in populational terms, one event in 
several years and not 200 events in one year . 
Is such an approach based on a legitimate method ological approach and suf ficiently supported by 
scientific evidence?  (IRA, Part B, pp. 42-45;  paras. 4.174-4.186 of New Zealand's FWS;  paras. 269-
271 and 295 of Australia's FWS;  para. 73 of New Zealand's opening statement;  and R 107 by 
New Zealand)  
Dr Sgrillo
: 
 765. This approach seems to be based in an arb itrary choice and not in scientific principles. 
Dr Latorre (Response to whole question)
: 
 
766. Australia's IRA provides little insight as to how the probability values were assigned to each 
of the six qualitative descriptors (high, moderate, lo w, very low, extremely low and negligible).  To 
my understanding, these probability intervals we re arbitrarily assigned based on the general 
knowledge of the pests and diseases, considering the opi nions of experts and stakeholders, to ensure 
that these probability ranges contained the actual valu es.  However, and at least in connection to 
European canker, these probability ranges are difficult to believe.  One of the main weaknesses is the 
range used to numerically explain the negligible descriptor.  The term "negligible" denotes something 
of so little consequence as to warrant no attention.  In other words, the probability of a negligible 
biological event would be almost certainly zero but different from zero.  Therefore, by no means can a 
negligible event range from 0 to a maximum of 1x10-6 with a midpoint of 5x10-7.  In doing so, the 
likelihood of a particular biological even t is overestimated.  As stated before, 5x10-7 is a relatively 
high probability value, even considering the lowest possible total volume of apples (50,000,000, AUS-2 p.19) that can ultimately be imported from New Zealand.  To my knowledge, little or no experimental information has been published with re gard to the likelihood of most of the biological 
events concerning the probability of entrance, est ablishment and spread of European canker.  
Therefore, unless the IRA team has additional inform ation (e.g., experimental data) not presented in 
this IRA, assigning these probability values can lead to weak conclusions.  I would strongly suggest 
reviewing the probability values given in Table 12 (AUS-2 p. 43), accepting that the maximum 
probability to be assigned to a negligible event should be such that one can be almost certain that this 
event will not occur in a given population, and that the minimum value should be different from zero.  
Then probability values for other descriptors can be  assigned, considering that if an event has a 
probability of one, there is certainty that the event will occur. 
                                                     
 
105 (footnote original ) Reference 07: Biosecurity Australia. Guidelines for import risk analysis. Draft 
September 2001. p. 86.  WT/DS367/11 
Page 146  
 
  Question 134 
Does Australia's IRA provide objective and coherent explanations for defining "negligible" as an 
interval between 0 and 10
-6? 
 
Dr Sgrillo : 
 
767. Australia doe not explain why the maximum value for the "negligible" range is 1E-6.  There 
is no scientific base to support the exclusive choice of  1E-6 because other ranges, as 0 to 1E-9 or to 
2E-6, could also be used, after adjustment of th e remaining ranges, without violating any scientific 
principle. 
Is that definition based on a legitimate methodol ogical approach?  Please comment on whether the 
intervals assigned by Australia's IRA correspond to an event that would almost certainly not occur.  (Para. 4.160 of New Zealand's FWS;  para. 274 of  Australia's FWS;  para. 73 of New Zealand's 
opening statement;  and R 96-98 by the Parties) 
 Dr Sgrillo
: 
 768. It is recognized that the numeric probabilities representing the qualitative descriptors in the 
IRA are to be interpreted in a per unit  basis.  However they should reflect the category concepts also 
in populational terms but this is not occurring in the present case. 
769. Considering the importation of 200.000.000 fru it per year the category negligible could 
represents 200 fruits per year.  However, an event that "would almost certainly not occur" should be 
expected to occur only on ce in each several years.
 
Dr Latorre (Response to whole question) : 
 770. Please refer to the answer to Question 133. 
IV. Question 135 
When performing a biological risk assessment, how  does the uniform distri bution compare to the 
triangular distribution and to the beta-PERT distri bution, in particular when modelling events that 
have a low or even "negligible" likelihood of occurring? 
 
Dr Sgrillo
: 
 
771. Firko and Podleckis (2000)106 describe the characteristics of the uniform distribution in pest 
risk assessment: 
"Uniform distributions are the simplest PDF (Probability Distribution Function);  
only a minimum and maximum value is needed to specify the distribution.  Every 
value between the minimum and the maximum has an equal probability of being 
selected by the sampling algorithm.  Unifor m distribution may be appropriate when 
there is little justification for assuming the some values are more likely than others or when data do not suggest a central te ndency.  Uniform distribution used for 
probability values that range over an order of  magnitude should be used with caution.  
If the analysts were thinking on a log scale, results could be overly conservative.  For 
                                                     
 
106 (footnote original ) Reference 04:  Firko, M.J. and Podleckis, E.V.  Likelihood of Introducing 
Nonindigenous Organisms with Agricultural Commodities:  Probabilistic Estimation.  In:  Ferson S, Burgman 
M., editors.  Quantitative methods for conservation biology.  Springer;  New York: 2000.  pp. 77–95.  WT/DS367/11 
 Page 147 
 
 
  example, consider a uniform distribution covering two orders of magnitude 
(minimum=0.0002, maximum=0.02).  Va lues between the minimum and the 
geometric mean (0.002) will be chosen only about 9% of the time, and values 
between the geometric mean and the maxi mum will be chosen about 91% of the 
time". 
772. For the same authors107 the limitations of the triangular distribution refers to the minimum and 
maximum values: 
Triangular distributions are specified by three values:  minimum, most likely, and 
maximum.  The relative frequency of the various values in the distribution is indicated by the shape of the curve, which is determined by the relative positions of 
the three parameters.  Values at or near  the most likely value are selected for 
calculations more often than values at or near the minimum and maximum.  
Triangular distributions can be used when it is fair to assume that some values are 
more likely than other, but have the disadvantage of not selecting values below the minimum and above the maximum.  Choi ce of the minimum and maximum values 
can be considered more important than choice of the most likely value because the 
minimum and maximum imply a high degree of assurance about the limit of the 
underlying distribution.  We use triangul ar distribution occasionally but avoid them 
because biological systems are seldom well represented by distributions with strict limits.  The arbitrary shape of the triangul ar distribution and its strict limits are 
indications that the precise nature of the distribution is not known. 
773. Also, by using a strict triangular shape about the mode, the triangular distribution may place 
too much emphasis on the most likely value, at  the expense of the values to either side. 
774. The Pert distribution also uses the most likel y value, but it is designed to generate a 
distribution that more closely resembles realis tic probability distribution as normal or lognormal 
distributions. 
775. Realistic stochastic models, however, are only developed when availa ble numeric data are 
sufficient to estimate, directly from real populations , the shape of the distri butions and the values of 
the respective parameters. 
(ii)
 Can you explain the advantages and disadvant ages of one with respect to the other? 
Dr Sgrillo : 
 
776. The uniform distribution requires only the ma ximum and minimum values but it generates 
less realistic samples. 
777. The triangular distribution is based on knowledge of the minimum and maximum and an 
inspired guess as to what the modal value might be108, however it emphasizes on the modal value, at 
the expense of the values to either side. 
778. From the three options the Pert distribution is expected to be the more realistic because it 
reduces the emphasis on the modal value. 
                                                      
107 Ibidem. 
108 ( footnote original ) http://rule-of-thumb.net/2008/09/0 6/random-numbers-out-of-triangular-
distribution/. Retrieved 23/February/2009. 
 WT/DS367/11 
Page 148  
 
  Please comment on the implications of a methodolog ical approach for a risk assessment that defines 
the minimum and maximum of a distribution, but not the central tendency of the distribution.  Could this type of risk assessment result in a distorted vi ew of the actual likelihood of an event?  (IRA, 
Part B, p. 42;  para. 4.187 of, and pp. 242 and 247 of Annex 4 to, New Zealand's FWS;  para. 312 of Australia's FWS;  para. 73 of New Zealand's opening statement;  and R 109 by New Zealand) 
 
Dr Sgrillo
: 
 779. The results of the simulations from a uniform di stribution will converge to its arithmetic mean 
([minimum+maximum]/2).  However, if the actual probability distribution of the process is skewed 
then the risk assessment will result in a distorted view of the reality. 
Dr Latorre (Response to whole question)
: 
 780. I am not in a position to answer this question. 
Dr Schrader (Response to whole question):
 
 
781. A Uniform distribution represents a distribution for which each value in the continuous range 
of values between minimum and maximum limits occurs with the same probability.  It is the simplest and least realistic method of the three methods men tioned here and is useful in situations, where a 
minimum and maximum value are available, but no  sufficient information to determine the most 
likely value.  This method implies a high degree of uncertainty
. 
782. The triangular distribution can be applied if a "most likely" estimate in addition to the 
minimum and maximum estimates is available.  This probability distribution favors the most likely value and should provide a better estimate of th e probabilities of reaching other values.  The 
distribution does not need to be symmetrical about the mean;  by this it can model a variety of different circumstances.  The disadvantage is that  it may emphasize too much the most likely value
, at 
the expense of the values to the two other sides to wards the minimum or maxi mum.  This distribution 
is easy to calculate and generate, but still limited  with regard to modelling real-world estimates. 
783. Though the beta-PERT distribution also uses and emphasizes the most likely value, it 
generates a smooth distribution curve that resemble s more closely a realistic probability distribution 
and places progressively more emphasis on values close to the most likely value.  The advantage of the PERT distribution is that its shape is simila r to the normal curve, without knowing the precise 
parameters of the related normal curve.  This re lates to the assumption th at realistic events or 
situations are normally distributed. 
Question 136 
Please explain what weight a uniform distribution range,  as used by Australia's IRA, attributes to the 
maximum value, as compared to the minimum value.  Is there any indication that the maximum value 
assigned to the uniform distribution range in the m odel used by the IRA gives appropriate weight to 
the maximum probability of a "negligible" event occurring? 
 
Dr Sgrillo
: 
 784. See Table 1, below. 
Does using a risk analysis software package which performs simulations that randomly select 
numbers from within the uniform distribution, eff ectively average the higher and lower ends of the 
probability range? 
  WT/DS367/11 
 Page 149 
 
 
  Dr Sgrillo : 
 785. Yes, even general software, as MS Excel, pr esents an acceptable performance.  For example 
15 simulations of 1.000 random unifo rm values between 0 and 1E-6 ge nerates an average of 4.9961E-
7, ranging from 4.84E-7 to 5.17E-7 what corresponds to an error of ± 3.5 % when compared with the 
expected average 5.00E-7. 
Please comment on whether the IRA' s use of the "negligible" range gives more weight to the upper 
bound of the uniform distribution range than the minimum bound. 
 
Dr Sgrillo
: 
 
786. The data of Table 1 represents the percentage of sampling, in each range, from a uniform 
distribution with minimum value = 0 and maximum va lue = 1E-6.  The table was prepared dividing 
the amplitude of each interval by the total amplitude (1E-6). 
Table 1. Percentage of sampling from a uniform distribution with minimum value = 0 
and maximum value = 1E-6 
Range Sampling (%) 
0<>1E-12 0.0001 
1E-12<->1E-11 0.0009 
1E-11<->1E-10 0.009 
1E-10<->1E-09 0.09 
1E-09<->1E-08 0.9 
1E-08<->1E-07 9 
1E-07<->1E-06 90 
Total 100 
 
787. Table 1 shows that 90% of the random number s generated in a simulation will fall in the 
range 1E-7 to 1E-6 and only 0.0001% of the ra ndom numbers will fall in the range 0 to 1E-12. 
If so, does the IRA give undue weight to the maxi mum probability of a "negligible" event occurring by 
assigning the upper bound of their uniform distribution to be 1 x 10E-6 bearing in mind the per apple 
methodology and the estimated annual volume of apples imported? 
 
Dr Sgrillo : 
 
788. In a logarithmic scale, where the weight is equally distributed among the various magnitude 
orders , the probability of sampling a number very close to zero is the same of sampling a number 
close to the upper bond of the distribution. 
789. However, as shown in table 1, in a decimal sc ale, there is much more chance of sampling a 
number close to the upper bond than close to zero. 
790. It is recognized that the numeric probabilities representing the qualitativ e descriptors in the 
IRA are to be interpreted in a per unit  basis.  However they have to reflect the category concepts also 
in populational terms. 
791. Considering 150.000.000 fruits impor ted per year the category negligible could represents 
150 fruits per year.  However, an event that "would al most certainly not occur" should be expected to 
occur only once in each several years . WT/DS367/11 
Page 150  
 
  Does each step in the model have to be estimat ed separately and then the average value taken 
forward as the input into the next step?  Or at ea ch step of the model, are the full distribution of 
output values effectively taken forward to the next st ep – not just the average value?  (IRA, Part B, 
pp. 17-19 and 42;  paras. 4.190-4.192 and 4.194- 4.195 of New Zealand's FWS;  and paras. 314-316 
of Australia's FWS) 
 
Dr Sgrillo
: 
792. The model runs according the following steps: 
(a) Generate a set of random inputs, one for each probability function; 
(b) Evaluate the model; 
(c) Store the result. 
793. The steps 1, 2 and 3 are repeated 1000-2000 times109 and then the output distribution is 
computed from the stored values. 
794. The fifth, 50th (or median) and 95th percentiles of the output distribution are then compared 
with the probability intervals in IRA's Table 12.110 
Dr Latorre (Response to whole question) : 
 795. I am not in a position to answer this question. 
Question 137 
Please comment on the relevance of the conflicting assumptions made by the Parties as to the 
varieties of apples and the magnitude of traded vo lumes that New Zealand could successfully export 
into Australia.  What role does volume of trade pl ay in the risk assessment used by Australia?  If 
volume of trade was overestimated, what signific ance would this have on the overall probability of 
entry?  (IRA, Part B, pp. 19 and 24;  paras. 4.194-4.203 of New Zealand's  FWS;  paras. 113-121 and 
325-343 of Australia's FWS;  and R 110 by New Zealand) 
 Dr Latorre
: 
 796. First, the risk of entrance would be related to the size of the population.   In this case, it will 
depend on the total volume of matu re apples annually imported by Au stralia.  In general, as the 
volume increases, so does the probability that a given biological event may occur, increasing the 
chances that N. Galligena  will gain entrance into Australia.  Therefore, it is very important for an 
accurate IRA to define objectivel y the eventual volume of mature apple that Australia would be 
importing from New Zealand annually. 
Dr Sgrillo
: 
 797. The general pest risk model can be expressed as follows
111: 
                                                      
109 (footnote original ) Reference 07:  Biosecurity Australia.  Gu idelines for import risk analysis.  Draft 
September 2001.  p. 87 
110 (footnote original ) IRA p. 43. 
111 (footnote original ) Reference 05: Bigsby, H. and J. Crequer.  1996.  Conceptual model for the 
management of pest risk.  Statistics in Ecology and Environmental Monitoring, Dunedin, June 1996, pp. 7-16.  WT/DS367/11 
 Page 151 
 
 
   Conseq Intro_ Prob Risk × = ...1 
 
798. Where Risk is the probability of introduction ( Prob_ Introd ) multiplied by the potential 
economic impact ( Conseq ). 
799. The probability of introduction can be estimated by112: 
 Entered) Prob_Estab Prev1(1 Prob_Intro ×−−= ...2 
 
800. Where Prob_Intro  is the probability of introduction, Prev  is the prevalence (proportion of 
units in the consignment that is infected/infested), Prob_Estab  is the probability of establishment and 
Entered  is the number of infected/infested unities that has entered into the importer country. 
801. The number of entered units can be estimate by: 
 ss Prob_Ingre rted Volum_Impo Entered × = ...3 
 802. Where Volum_Imported  is the volume (units) imported and Prob_Ingress  is the probability of 
ingress into the importer country. 
803. Making the necessary substitutions the general e quation for pest risk can be derived as: 
 ()( )Conseq Prob_Estab Prev11 Riskss Prob_Ingre rted Volum_Impo× ×−−=×
...4 
 804. This is the demonstration that the risk is directly proportional to the volume imported. 
805. Figure 4 below presents a chart generated with  equation 4, applying the following theoretical 
values:  consequences = 1;  prevalence = 0.001 (0.1%);  probability of establishment = 0.005 and 
Probability of ingress = 0.001. 
 
Figure 4. Effect of the volume of trade on the phytosanitary risk 
                                                      
112 (footnote original ) Reference 08: Baker, R.T., J.M. Cowl ey and D.S. Harte.  1993. Pest risk 
assessment.  Lynfield Plant Protection Centre Publications, New Zealand, No. 1, 12 pp. WT/DS367/11 
Page 152  
 
  806. Figure 4 shows that the final risk is a continuous function of the volume of trade.  In many 
cases the probability of establishment is a function of  the size of the population that has entered.  
Therefore the introduction process become non-linear and more complicated model are necessary.  
However always the risk will be proportional to the volume of trade. 
807. Limiting the volume to be imported can be used  as valid phytosanitary measure to reduce the 
risk to an acceptable level. 
Question 138 
In defining risk, please comment on whether is it ap propriate to suggest that where Australia's IRA 
assigns "negligible" likelihoods to steps in a given pat hway, such events should be treated as breaking 
the chain of causation for disease transmission, and that therefore, the assessment of risk should 
cease?  Would it be a legitimate methodological approach for risk assessors to consider disease 
transmission pathways with steps that approach a probability of zero?  Please comment on whether it is a legitimate methodological approa ch to continue a risk analysis if the likelihood of a step in a 
continuum of events is considered negligible or the step is considered almost certain not to occur?  
(Para. 4.160 of New Zealand's FWS;  para. 274 of Australia's FWS;  para. 59 of the United States' 
Third Party submission;  para. 73 of New Zealand's  opening statement;  and R 96 by New Zealand) 
 
Dr Latorre
: 
 808. There are multiple importation steps (eight steps) to explain the possible flow of N. Galligena  
during the process necessary for importing mature apple fruits from New Zealand.  Australian's IRA 
assigned a probability value to each step.  However, some of these steps (e.g., Steps 3, 5 and 7) are 
indeed mere possibilities (hypothesis ra ther than true facts) that need to be confirmed.  In such cases, 
a probability equal to zero should be assigned or even  better, disregard the steps considered almost 
certain not to occur. 
Dr Schrader:
 
 
809. If one risk element is rated "negligible", it has to be put into question, whether it makes sense 
to proceed further with the risk assessment.  As an  example, the Canadian Risk Assessment Scheme 
(Plant Health Risk Assessment, Commodity Risk Assessment, Canadian Food Inspection Authority, 
Plant Health Risk Assessment Unit, Science Advi ce Division) uses a risk estimation matrix, where 
ratings for likelihood of introduction are combined with  ratings for consequences of introduction.  The 
scheme uses three different scores for ratings:  negl igible, low, medium and high.  "Negligible" in 
combination with any other rating (including high) r esults in "negligible".  In comparison to this, the 
Australian IRA guidelines assign "negligible" to a high likelihood of entry, establishment and spread 
combined with a negligible impact, but assigns "ver y low" (which is still meeting Australia's ALOP) 
to a negligible likelihood of entry, establishmen t and spread combined with an extreme impact. 
Dr Sgrillo : 
 810. It depends on what is the meani ng of "almost certain not to occur
". 
811. If "almost certain not to occur " refers to the probability of occurrences in a per fruit bases and 
is described by the probability ra nge 0 to 1E-6 then the risk assessment should proceed because the 
consequences have to be considered and the comb ination of a negligible probability of introduction 
with huge consequences could ge nerate an unacceptable risk. 
812. If "almost certain not to occur " refers to the likelihood of occurrences in the population as one 
occurrence in each several years, fo r example, then the probability range  could be many times lower.   WT/DS367/11 
 Page 153 
 
 
  In this case the path could be assessed to be re moved from the model to increase the clarity and 
simplicity; and the causal chain could be broken. 
813. If "almost certain not to occur " mean that the possibility to occur is only a theoretical 
supposition and there are no records that the event h as ever occurred then th e path can be removed 
from the model and the causal chain would be broken. 
Question 139 
Please comment on whether, from a technical persp ective and as described in Australia's IRA, the 17 
specific measures that have been challenged by New Zealand can be distinguished as either principal 
or ancillary?  (R 14-26 by the Parties) 
 Dr Latorre
: 
 814. As stated in the answer to Question 93, phyt osanitary measures which act directly to lower 
the risk of entrance, establishment and spread of N. Galligena  should be considered as principal 
measures, while those measures implemented to support any active measure (principal measures) 
should be regarded as ancillary measures.  The latte r measures make sense only if principal measures 
exist. 
Dr Schrader:
 
 815. The IPPC Standards do not use the terms "princ ipal" and "ancillary".  However, it can be 
interpreted that Australia attempts a systems approach  as described in ISPM No. 14.  In this standard, 
independent and dependent measures are differentia ted.  A systems approach needs at least two 
independent measures.  See also answer to question 140. 
Dr Sgrillo
: 
 816. The distinction between "principal" and "ancilla ry" measure is not recognized by IPPC and, 
therefore, there is no international guidance to di stinguish the measures in plant protection context. 
817. However the measures could be technically di stinguished supposing that the "principal" 
measures are the ones having the direct purpose to  prevent the introduction and/or spread of 
quarantine pests and that the "ancillary" measures support, verify and operationalise the principal 
measures. 
Question 140 
Please comment on the extent to which IPPC st andards and other relevant documentation recognize 
any distinction between principal and ancillary measures, that is, between measures active in risk 
reduction and those which are designed to implement or support such measures.  (R 24 by Australia) 
 
Dr Latorre
: 
 
818. To my understanding, principal and ancillary ar e terms not used officially to distinguish 
between main and auxiliary (secondary) phytosanitary  measures.  However, the meaning of these two 
terms is understandable. WT/DS367/11 
Page 154  
 
  Dr Schrader:
 
 819. As outlined in question 139, the 17 specifi c measures having been challenged by New 
Zealand, can be interpreted to be an attempt of a systems approach according to ISPM No. 14:  "The 
use of integrated measures in a systems approach for pest risk management".  According to this 
standard, systems approaches integrate measures for pest risk management in a defined manner and 
"could provide an alternative to single measures to meet the appropriate level of phytosanitary 
protection of an importing country."  A systems a pproach requires integrating different measures, 
with a cumulative effect."  It includes at least tw o measures that are independent of each other, and 
may include any number of measures that are dependent on each other. 
820. The standard further outlines, that the importing country is making the decision regarding the 
acceptability of a systems approach, "subject to cons ideration of technical justification, minimal 
impact, transparency, non-discrimination, equiva lence, and operational feasibility.  A systems 
approach is usually designed as an option that is  equivalent to but less restrictive than other 
measures." 
821. Especially where the alternative is prohibiti on, it is "important to consider systems 
approaches among risk management options because the integration of measures may be less trade 
restrictive than other risk management options."  An advantage of the systems approach is the ability 
to address variability and uncertainty by modifying the number and strength of measures to meet the 
appropriate level of phytosanita ry protection and confidence. 
822. A systems approach may include: 
• measures applied in the place of production,  during the post harvest period, at the 
packinghouse, or during shipment and distribution of the commodity 
• cultural practices 
• field treatment, 
• post harvest disinfestation, 
• inspection and other procedures 
• risk management measures designed to pr event contamination or re-infestation 
• pest surveillance, trapping and sampling 
• measures that do not kill pests or reduce their prevalence but reduce their potential for 
entry or establishment (safeguards) 
 823. According to ISPM No 14, "systems approaches may be considered when one or more of the 
following circumstances apply: 
- a particular measure is: 
• not adequate to meet the appropriate level of phytosanitary protection of the 
importing country 
• not available (or likely to become unavailable) 
• detrimental (to commodity, human health, environment) 
• not cost effective 
• overly trade restrictive 
• not feasible". 
 824. An important requirement of the systems approach is that "importing countries, in 
consultation with the exporting country where a ppropriate should select least trade restrictive 
measures where there are options."  WT/DS367/11 
 Page 155 
 
 
  Dr Sgrillo : 
 825. The terms "principal measures" and "ancillary  measures" are not defined in the IPPC. 
826. There are methods and operations designed to implement and support phytosanitary 
measures, as defined in the ISPM 5 (Glossary of phytosanitary terms-2008).
113 
"Phytosanitary action:  An official operation,  such as inspection, testing, surveillance 
or treatment, undertaken to implement phytosanitary measures;" 
"Phytosanitary procedure :  Any official method for implementing phytosanitary 
measures including theperformance of inspecti ons, tests, surveillance or treatments in 
connection with regulated pests;" 
"Phytosanitary measure :  Any legislation, regulation or official procedure having the 
purpose to prevent the introduction and/or spread of quarantine pests, or to limit the economic impact of regulated non-quarantine pests;" 
Question 141 
Please comment on whether, in general, "ancilla ry" and "principal" measures can share a common 
scientific basis.  Does the scientific justification of  an ancillary measure necessarily depend on 
whether its related principal meas ure is found to be scientifically justified?  (R 25 by the Parties) 
 
Dr Deckers
: 
 827. No, the ancillary measures don't share always a common scientific base with the principal 
measures.  So is the requirement of the inspecti on of the new planted trees on European canker and 
the necessity to treat them for NG totally different  from the NG contamination of apples on adult trees 
in an orchard.  The same is true for the pruning of fire blight infections:  technically this should be 
done to reduce the impact of the disease, but of course this pruning could hide the presence EA infection in an orchard. 
Dr Latorre
: 
 828. Yes, ancillary measures and principal measures can share a common scientific basis, but the 
justification of the ancillary measures depends on th e existence of scientifically justified principal 
measures. 
Dr Schrader:
 
 
829. Article 2 (2) of the SPS-Agreement states that:  "Members shall ensure that any sanitary or 
phytosanitary measure is applied only to the extent necessary to protect human, animal or plant life or 
health, is based on scientific principles and is not maintained without suffici ent scientific evidence, 
except as provided for in paragraph 7 of Article 5. 
830. Article 3 (3) of the SPS-Agreement states that:  "Members may introduce or maintain sanitary 
or phytosanitary measures which result in a higher level of sanitary or phytosanitary protection than 
would be achieved by measures based on the rele vant international standards, guidelines or 
recommendations, if there is a scientific justification, […]" 
                                                      
113 (footnote original ) References 03:  International Plant Protection Convention, International Standard 
for Phytosanitary Measures No. 11:  Glossary of Phytosanitary Terms, 2008. WT/DS367/11 
Page 156  
 
  831. According to the IPPC, phytosanitary measures ha ve to be technically justified ("Contracting 
parties shall not, under their phytosanitary legislation,  take any of the measures specified in paragraph 
1 of this Article unless such measures are made ne cessary by phytosanitary considerations and are 
technically justified."  Article VII 2a, IPPC 1997).  The definition given in the IPPC for "technically 
justified" is as follows:  "justifie d on the basis of conclusions reach ed by using an appropriate pest 
risk analysis or, where applicable, another comp arable examination and evaluation of available 
scientific information."  The IPPC does not use the term "scientifically justified". 
832. There is no direct indication (neither in the IPPC nor in the SPS Agreement), that the 
scientific justification of a dependent (ancillary) m easure depends on the scientific justification of an 
independent measure. 
Dr Sgrillo
: 
 833. Some times the "principal" and "ancillary" measures can share the same technical 
justification.  Measures that confirm or inspect other measures could share the same scientific 
justification. 
834. However this is not always true.  It does not necessarily follow that where a "principal" 
measure is found to be technically justified relate d measures are also automatically consistent with 
those justifications. 
Question 142 
Please comment on whether the alternative measur e proposed by New Zealand relating to inspection 
by AQIS officials, verification of  standard commercial practice and pr ovision of packing house details 
imposed by Australia on the importation of apples would achieve Australia's ALOP. 
 
Dr Sgrillo
: 
 835. It is not possible to evaluate if the measur es required by Australia and the alternative 
measures proposed by New Zealand have the same  effect because Australia does not describes the 
expected effect of the required measures in ach ieving Australia's ALOP.  It would be necessary to 
know how much of the estimated risk would be  reduced by each of the measures required by 
Australia. 
How does this measure compare to the relevant requi rements identified by Australia's IRA in terms of 
risk mitigation?  Under what circumstances, if at a ll, could this alternative measure proposed by 
New Zealand achieve Australia's ALOP?  (IRA, Part B, pp. 4-5 and 314-315;   paras. 4.524-4.539 of 
New Zealand's FWS;  para. 1106-1113 of Australia's  FWS;  and para. 73 of New Zealand's opening 
statement) 
 
Dr Sgrillo
: 
 
836. See to the first part of this response. 
Dr Deckers (Response to whole question) : 
 837. It seems to be logic that the existing qua lity assurance procedures in New Zealand apple 
production would be audited by AQIS officials during inspection and that not all the work should be 
done in double.  Orchard inspections for fire bli ght and for NG will not be included by the standard 
procedures of apple production and will be a supplemen tary task.  The very intensive control row per 
row, proposed by AQIS for European canker for each or chard will not be evident to realise at orchard 
level.  Why not concentrating the observations on the most susceptible appl e cultivars?  The same  WT/DS367/11 
 Page 157 
 
 
  consideration can be made for fire blight inspec tions at orchard level:  why not concentrate on the 
most susceptible varieties?  This will increase th e chances to find infections in the orchards. 
Dr Latorre (Response to whole question) : 
 838. It is reasonable to audit rather than inspect, considering that both Australia and New Zealand 
have a highly professional and very reliable Quaran tine Service.  Moreover, both countries have 
previously agreed to establish a system of aud iting (e.g., stone fruits and tomatoes) rather than in situ  
inspection by officials from the Au stralian Quarantine and Inspection Service (AQIS).  This auditing 
system is technically feasible, economically less rest rictive, and should satisfy the appropriate level of 
protection (ALOP) established by Australia.  Certai nly, it can facilitate trade activities between both 
countries. 
839. I see no reason why auditing would interfere w ith mitigation measures.  Mitigation measures 
should be applied in accordance with a final prot ocol accepted by both countries, while auditing 
should verify only the correct application of the a pproved mitigation measures.  On the other hand, if 
in situ  inspection is performed, there are no substantiate d reasons to allow thinking that this procedure 
per se  would lower the risk of entrance, establishment and spread of N. Galligena  in Australia. 
 
__________