Risk Management Proposal:   
Prunus  Plants for Planting  
 
 
   
 
 
 
 
28 June 2019 
 
 
 
  
 
  
 
 
 
 
 
  
 
 
 
  
 
 
 
  
 
 
 
 
  
 
 
Plant Germplasm Imports  
Plants  & Pathways Directorate  
Ministry for Primary Industries  
TSB Building  
147 Lambton Quay  
PO Box 2526  
Wellington 6140  
New Zealand  
 
Tel: +64 4 894 0100  
 
Email: plantimports@mpi.govt.nz 
i Table of Contents  
Submissions  ............................................................................................................. 2 
Summary  ................................................................................................................... 3 
1. Introduction ........................................................................................................ 6 
 Objective  ........................................................................................................... 6 
 Purpose  ............................................................................................................ 6 
 Background ....................................................................................................... 6 
 Commodity description  ..................................................................................... 7 
 Scope of this risk management proposal  .......................................................... 7 
 Format of the draft standard  ............................................................................. 8 
2. Context  ................................................................................................................ 9 
 Domestic  ........................................................................................................... 9 
 International  .................................................................................................... 10 
 Strength of measures  ..................................................................................... 10 
3. Risk management approach  ........................................................................... 12 
 Source information  .......................................................................................... 12 
 Risk m anagement measures  .......................................................................... 12 
4. Proposed risk management measures for Prunus  plants for planting ....... 23 
 Proposed requirements for screening for regulated pests  .............................. 23 
 Proposed requirements for post entry quarantine  ........................................... 27 
 Summary of regulated pests  ........................................................................... 29 
5. Feasibility and practicality of proposed requirements  .................................  49 
 Import permit  ................................................................................................... 49 
 Plants from an MPI -accredited offshore facility or produced under an Export 
Plan 50 
 Biosecurit y clearance  ...................................................................................... 51 
  
2 Submissions  
The Ministry for Primary Industries (MPI) invites comment from interested parties on the proposed new 
import health standard for Prunus  Plants for Planting (i.e. nursery stock) . The proposed import health 
standard is supported by this risk management proposal.  
The purpose of an import health standard is defined as follows in section 22(1) of the Biosecurity Act 
1993 (the Act): “An import health standard specifies requirements that must be met to effectivel y 
manage risks associated with importing risk goods, including risks arising because importing the goods involves or might involve an incidentally imported new organism”.  
MPI must consult with interested parties in accordance with section 23 of the Act bef ore issuing or 
amending an import health standard under section 24A of the Act. MPI therefore seeks formal comment 
on the proposed import health standard.  
The following points may be of assistance in preparing comments:  
 
• Wherever possible, comments should be specific to a particular section/requirement of the 
standard;  
• Where possible, reasons, data and supporting published references to support comments are requested;  
• The use of examples to illustrate particular points is encouraged.   
MPI encourages respondents to forward comments electronically. Please include the following in your 
submission:  
 
• The title of the consultation document in the subject line of your email;  
• Your name and title (if applicable);  
• Your organisation’s name (if applicable);  
• Your addr ess. 
Send submissions to: plantimports@mpi.govt.nz
. 
If you wish to forward submissions in writing, please send them to the following address.  
Plant Germplasm Imports  
Plants  & Pathways Directorate  
Ministry for Primary Industries  
PO Box 2526  
Wellington 6140  
New Zealand  
All submissions must arrive by close of business on 8 August 2019. Submissions received by the 
closure date will be considered during the development of the final standard. Submissions received after 
the closure date may be held on file for consideration when the issued standard is next revised/reviewed.  
Official Information Act 1982  
Please note that your submission is public information and it is MPI policy to publish submissions and the review of submissions on the MPI website. Submissions may also be the subject of requests for information under the Official Information Act 1982 (OIA). The OIA specifies that information is to be 
made available to requesters unless there are sufficient grounds  for withholding it, as set out in the OIA. 
Submitters may wish to indicate grounds for withholding specific information contained in their 
submission, such as the information is commercially sensitive or they wish personal information to be withheld.  Any decision to withhold information requested under the OIA is reviewable by the 
Ombudsman.    
3 Summary  
(1) This summary gives an overview of the proposed MPI revision to import requirements for Prunus  
plants for planting (nursery stock), as identified in the draft Import Health Standard: Prunus  Plants 
for Planting (hereafter referred to as ‘the draft standard’).  
(2) The subject of public consultation  is the requirements  of the draft standard.  This risk 
management proposal  supports the draft standard and should be read i n full, and in conjunction 
with the draft standard , to understand the rationale behind the proposed import requirements and 
the import health standard development process undertaken by MPI.  
Background  
(3) Prunus  plants for planting have previously been imported under the Prunus  schedule of the MPI 
Import Heath Standard (IHS) 155.02.06: Importation of Nursery Stock.  
(4) MPI has reviewed the Prunus  schedule of the above standard because the existing  requirements  
are no longer considered appropriate to manage risk, and may not be commensurate with the 
risk. This can result in ineffective risk management, either because import requirements are too 
stringent ( in relation to the level of risk), or because the y do not manage the risk from known 
regulated pests associated with Prunus  in accordance with MPI’s current appropriate level of 
protection.  
(5) MPI has developed new proposed phytosanitary import requirements in accordance with New Zealand’s obligations under the World Trade Organisation (WTO)  Agreement on the Application 
of Sanitary and Phytosanitary Measures, and taking into account the appropriate level of 
protection that MPI has established for plants for planting.  
(6) The proposed measures have been developed based on information in the MPI Import risk 
analysi s: budwood/ dormant cuttings of Prunus  spp..  The risk analysis is available on the 
biosecurity consultations page
 of the MPI website under the heading Draft import health standard 
for Prunus  plants for planting.  
Scope of the draft standard  
(7) The draft standard describes the phytosanitary import requirements for importing new commercial 
varieties of Prunus  spp. ‘stonefruit ’ (including apricot, cherry, nectarine, peach and plum ) and 
ornamental varieties into New Zealand , for further propagation.  
(8) The draft standard applies to dormant cuttings and tissue cultures of all species and hybrids of 
Prunus  plants for planting that are l isted as permitted in the MPI Plants Biosecurity Index (PBI) . 
Format of the draft standard  
(9) The draft standard has been prepared as a stand- alone document that includes only the 
phytosanitary import requirements for Prunus  plants for planting. This is a similar  format as the 
recently issued Import Health Standard for Actinidia  Plants for Planting , but has been up dated in 
accordance with current generic MPI templates for import health standards . 
Screening for regulated pests  
(10) The approach taken when developing phytosanitary measures for Prunus  plants for planting is 
similar to that applied to other horticultural species under the existing  import health standards 
155.02.06: Importation of Nursery Stock  and Actinidia  Plants For Planting . 
(11) The draft standard proposes some disease screening requirements  that were not previously 
required for Prunus  plants for planting. This includes applying specific environmental conditions 
that are likely to  be conducive to growth and/or symptom expression of certain types of regulated 
pests (for example including bacteria, fungi and oomycetes).   
4 a) Such measures are consistent  with New Zealand’s appropriate level of protection for other 
classes of regulated pest  and take into account the threat posed by these types of pest, 
including very high risk organisms such as Xylella fastidiosa,  Ceratocystis fimbriata and 
Phytophthora ramorum . Similar measures are in place  for  other plant genera (for example 
Actinidia ) and would likely be applied to other genera when these import health standard 
schedules are updated;  
b) If adopted for Prunus plants for planting, similar measures are likely to be applied to 
other high value crops with similar risk profiles when  those stan dards are reviewed  in 
due course . Therefore,  MPI is seeking feedback on these measures from all parties 
with an interest in protecting New Zealand from biological risk associated with 
imported plants for planting.  
c) These measures , along with alternative measures  that MPI has considered for managing 
risk from these classes of regulated pest , are discussed further in Parts 3.2.2.1  and 4.1.1  of 
this risk management proposal  
(12) Methods used to detect regulated pests whilst they are being screened for disease include:  
a) Two plant health inspections per week, by the operator of the facility holding the plants, for the duration of the quarantine period;  
b) Ten plant health inspections , by an MPI Inspector, over the duration of the quarantine 
period;  
c) Mandatory  testing (for example using polymerase chain reaction [PCR] or culture- based 
techniques) to detect specified regulated pests (as identified in Schedules 1 and 2 of the 
draft standard);  
d) Diagnostic testing as needed to identify any disease symptoms that are observed whilst 
plants are in post entry quarantine.  
(13) Disease screening requirements are discussed in Part 4.1
 of this risk management proposal.  
Post entry quarantine 
(14) It is proposed that the minimum quarantine period will be 2 1 months, comprising two growing 
seasons with a two month period of dormancy between seasons.  
(15)  Plants will be held in a post entry quarantine greenhouse to prevent any regulated pests 
escaping into the wider environment.  
a) The greenhouse must be approved under the MPI Facility Standard: Post Entry Quarantine 
for Plants ; 
b) Plants must be held in a Level 3B greenhouse for the first growing season, but may be 
transferred to a Level 3A greenhouse for the period of dormancy and the second growing 
season  provided that mandator y testing ( as described in Part 4.1.3  of this risk management 
proposal) demonstrates freedom from all pests that can only be contained within a Level 3B 
greenhouse.  
(16) The proposed requirements for post entry quarantine are discussed in Part 4.2 of this risk 
management proposal . 
Offshore risk management  
(17) Part 1. 6 of the draft standard gives three options for importing Prunus  plants for planting into New 
Zealand, as follows:  
a) Plants may be produced under an Export Plan ; 
b) Plants may be produced at an Offshore Facility ;  
5 c) Plants may be produced in any way other than the options listed above.  
(18) When plants are produced at an MPI -approved source using either  of the first two options listed 
above, phytosanitary measures for some (or all) regulated pests listed in the standard will be 
applied prior to export . MPI will recognise agreed- upon measures as meeting some, or all  
requirements of the standard. D epending on what measures are applied prior to export, there will 
be fewer disease screening requirements in New Zealand. This means that the time taken for  
disease scree ning in New Zealand may be shorter, and/or may be done in a quarantine 
greenhouse that provides a lower level of containment than a Level 3B greenhouse . These 
decisions will be made on a case by case basis.  
(19) MPI may require plants produced using one of the first two options to undergo audit testing on arrival in New Zealand to verify the effective application of offshore phytosanitary measures. If this is the case, this testing will be done in a post entry quarantine facility after the plants arrive in 
New Z ealand.  
(20) When plants are produced in any other way, all of the measures described in Part 2.3 of the draft 
standard will need to be applied in post entry quarantine in New Zealand.  
(21) More detail about options for offshore risk management are provided in Part 3.2.1
 of this risk 
management proposal.  
 
   
6 1. Introduction  
 Objective  
(22) MPI’s objective in developing a new import health standard for Prunus  Plants for Planting is to 
ensure that biosecurity risk associated with imported material is managed appropriately  to give 
the New Zealand stonefruit  industry , and any other importers,  ongoing access to new germplasm . 
 Purpose  
(23) The purpose of this risk management propos al is to:  
a) Summarise the known biosecurity risks that may be associated with imported Prunus  plants 
for planting;  
b) Show how the measures proposed in the draft standard  will appropriately  manage 
biosecurity risks,  and are consistent with New Zealand’s domesti c legislation and 
international obligations ; 
c) Provide information to support the consultation on the draft standard.  
(24) The risk management proposal is not itself the subject of consultation. However, MPI will accept 
comments and suggestions on the risk management proposal in order to improve future 
consultations on import health standards.  
 Background  
(25) The existing  import requirements for Prunus  plants for planting were established in the Import 
Health Standard 155.02.06: Importation of Nursery Stock , issu ed in 2004. Before that imports 
occurred under previous versions of that standard.  The import requirements for Prunus  have 
been amended several times since 2004, but have  never been  comprehensiv ely review ed. 
(26) All Prunus  plants for planting must undergo disease screening to verify that they are free from 
regulated pests. This can be done either offshore, or on arrival in New Zealand, or a combination 
of both.  
(27) Prunus  germplasm is one of the most commonly imported genera  for use in the production of 
high value crops  in New Zealand . 
a) All consignments imported since 2009 have been from MPI -accredited offshore facilities ; 
b) Under the existing  import health standard, t he minimum quarantine period for plants from 
accredited facilitie s is nine months of active growth in a Level 2 post entry quarantine 
greenhouse, spread over two growing seasons . As an alternative, plants may be transferred 
to a Level 1 post entry quarantine site after six months continuous active growth in Level 2. If this is done, the minimum quarantine  period is extended to a to tal of 12 months active 
growth;  
c) Plants that are not from an MPI accredited facility must undergo quarantine in a Level 3B 
post entry quarantine greenhouse.  In this case, t he existing  standard s pecifies a minimum 
quarantine period of  24 months  active growth.  
(28) Because t he New Zealand stonefruit  industry relies on ongoing imports of new Prunus  
germplasm to remain competitive, and in recognition of the fact that  the existing  import 
requirements have not been reviewed since 2004, MPI has prioritised revising and re- issuing 
phytosanitary import requirements for this commodity .  
7 
 Commodity description 
(29) The draft standard applies only to eligible  members of the Prunus  genus (including apricot, 
cherry, p each, plum , nectarine and ornamental cultivars ) that are currently listed in the MPI  Plants 
Biosecurity Index  (PBI)  with an import specification of “ L2, L3 see 155.02.06 under Prunus ”. 
Interspecific hybrids will be eligible for import , provided that every species in the parentage is 
identified with the full scientific name (genus and species)  and is listed as eligible in the Plants 
Biosecurity Index . 
(30) The following plant parts will be eli gible for import:  
a) Dormant cuttings;  
b) Tissue cultures derived from aerial plant parts.  
i. The draft standard defines tissue cultures as ‘plants in vitro  that have been prepared as 
tissue culture from one parent by asexual reproduction (clonal techniques) under sterile 
conditions’;  
ii. “Plants in vitro ” is defined as ‘a commodity class for plants growing in an aseptic 
medium in a closed container’ (in ISPM 5: Glossary of phytosanitary terms ); 
iii. Tissue cultures must be derived from aerial plant parts. The standard will not specify the type of aerial plant parts that may be used, but this can include tissue cultures 
derived from stems, shoots, leaves, terminal and axillary buds, flowers, petiole 
segments, anthers, pollen, seeds, embryos and endosperm;  
iv. Tissue cultures deri ved from root or basal stem tissues close to the soil level will not be 
eligible for import.  This is because these types of material were excluded from the 
scope of the MPI risk analysis for this commodity.  
(31) Reference is made to ‘ Prunus  plants for planting’  throughout this document. When this phrase is 
used, it applies only to dormant cuttings and tissue culture s. In the context  of this document , the 
phrase does not apply to any other types of Prunus  germplasm  (such as whole plants, pollen, or 
seeds).  
 Scope of this risk management proposal  
(32) This risk management proposal includes:  
a) Background information about MPIs approach to managing risk from plants for planting;  
b) A description of generic disease screening measures that will be applied to all Prunus  plants 
for planting imported into New Zealand to maximise the likelihood of inducing symptoms of 
infection by known regulated pests and by unknown risk organisms;  
c) A description of specific testing that is proposed to give assurance that imported germplasm 
is free from regulated pests that may not display visible disease symptoms in post entry 
quarantine;  
d) A discussion on the feasibility and practicality of the proposed risk management measures.  
(33) This risk management proposal does not:  
a) Identify all regulated species of fungi and oomycetes which MPI considers will be detected 
by the generic measure of growing season inspection during the proposed minimum 
quarantine period of 21  months  in a Level 3B quarantine greenhouse  (as described in Part 
4.2 of this risk management proposal);  
b) Identify any species of insects or mites that may be associated with the commodity;   
8 c) Identify individual species of phytoplasma that may be associated with P runus  plants for 
planting.  
(34) Information in this risk management proposal is based on the MPI risk analysis: budwood/ 
dormant cuttings of Prunus  spp. (available on the b iosecurity consultations page  of the MPI 
website) . Unless a specific reference is included in the text of this risk management proposal, all 
information is drawn from the content of the risk analysis and all primary references can be found 
in that document . 
 Format of the  draft standard 
(35) MPI has prepared the draft standard as a stand- alone document that only contains  phytosanitary 
import requirements for Prunus  plants for planting.  This is intended to  help ensure that 
requirements are easy to understand. The format  is similar to the  format used when developing 
import requirements for Actinidia plants for planting, which were the subject of formal public 
consultation in 2018 , but has been updated to reflect current generic MPI templates for import 
health standards . 
(36) Rather than using the term ‘nursery stock’, the commodity type is referred to as ‘plants for 
planting’. This change has been made to be consistent with the terminology used in the International Standards for Phytosanitary Measures (ISPM’s) as follows.  
a) ‘Plants for planting’ is defined in ISPM 5: Glossary of phytosanitary terms  as ‘Plants 
intended to remain planted, to be planted or replanted’ ; 
b) ‘Planting’ is defined as ‘Any operation for the placing of plants in a growing medium, or by grafting or similar operations, to ensure their subsequent growth, reproduction or 
propagation’.  
(37) Parts 1 – 3 and the Schedules  to the draft standard  set out all biosecurity requirements for 
importing Prunus plants for planting. The Introduction to the draft standard, and any information 
contained in guidance boxes, does not form part of the legal requirements, and is intended to 
provide general information about  the draft standard.  
(38) The draft standard identifies all priority regulated pests  associated with Prunus  plants  for planting 
that could have a significant  adverse impact on stonefruit , other crops  and/or the New Zealand 
environment. For example this includes species such as Plum pox virus  and Xylella fastidiosa, as 
well as the genera Phytophthora spp. and ‘Candidatus Phytoplasma’  spp.. The draft standard 
also identifies regulated pests that may  have a more restricted impact , but that require specific 
testing to verify their absence.  This applies to pests that may not induce visible symptoms on 
plant s in quar antine (for example including certain species of regulated virus that are restricted to 
the Prunus  genus). All of these pests , and the required testing measures,  are listed in Schedules 
1 and 2 of the draft standard.  
a) A full list of regulated pests is ident ified in BORIC [note: the full list will eventually  be listed in 
the new PIER (Plant Import and Export Requirements) tool, currently being developed by 
MPI]; 
i. If detected in imported Prunus  plants for planting, MPI will identify the causal agent of 
disease symptoms and confirm their regulatory status by reference to the 
MPI 
Biosecurity Organisms Register for Imported Commodities (BORIC)  database, not the 
import health standard;  
ii. If symptoms are caused by an organism that is not listed in BORIC , the MPI Chief 
Technical Officer (CTO) will make a decision on the regulatory status of that organism, 
and will update BORIC  accordingly;  
iii. This reflects the approach taken in the risk analysis, where MPI undertook a ‘selected hazard identification’ for fungi and oomycetes. The hazard identification did not attempt  
9 to identify all known fungi and oomycetes which should be regulated pests of Prunus . 
This is because the generic disease screening measures proposed in the draft standard 
are considered sufficient to manage risk from many fungi and oomycetes  in accordance 
with MPI’s appropriate level  of protection, regardless of whether the organism is listed 
in the standard.  
b) A risk assessment cannot identify all possible pests of concern because unexpected pest 
associations occur. This is one of the reasons plants for planting require post entry 
quarantine . Therefore, regulated pests unlikely to display visible signs or symptoms unless 
plants are screened for disease in post entry quarantine, are not generally listed in the 
standard, but are instead listed in BORIC. In particular, this applies to most  species of fungi 
and oomycetes.  These pests will be effectively contained within a Level 3B quarantine 
greenhouse. Similarly insects and mites, for which generic treatments are applied to 
manage the risk, are very unlikely to be associated with plants for  planting, so are also not 
listed in the standard but are listed in BORIC . If insects or mites are observed during 
inspections by an exporting country NPPO, their regulatory status should be determined by 
reference to BORIC . 
(39) Not all pests on plants for planting can be identified by an exporting country NPPO using 
standard phytosanitary certification procedures (if  they do not display visible signs and 
symptoms ). Therefore, unlike goods which receive clearance on arrival (e.g. fresh produce) and 
that are covered by a phytosanitary certificate which includes a declaration of pest freedom, in an 
import health standard for plants for planting MPI generally requires additional measures to be 
applied before granting biosecurity clearance (i.e. screening for disease in post entry quarantine).  
Disease screening and post entry quarantine requirements  proposed for Prunus plants for 
planting are identified in Parts 2.3 and 2.4 of the draft standard.  
2. Context  
 Domestic 
(40) Maintaining plant health is a key outcome of New Zealand’s biosecurity system. The system is 
regulated by MPI, through the Biosecurity Act 1993. Section 22 of the Act describes an import 
health standard and outlines the types of matters that should be considered in an import health standard.  
(41) The biosecurity system in New Zealand operates as a series of components ( pre-border, border 
and post border) that together provide a high level of assurance that regulated pests  are unlikely 
to establish in New Zealand. No one part of the system is able to achieve the necessary protection on its own.  
(42) No biosecurity system can  reduc e risk to zero. This is not feasible, and nor is it desirable. The 
objective of New  Zealand’s system  is to reduce to an appropriate level the likelihood of unwanted 
impacts occurring. Within this system, the objective of an import health standard is to effectively 
manage the risks associated with imported goods in order to reduce to an appropriate level the 
likelihood of introduction ( entry and establishment ) of regulated pest s (including pests, diseases 
and weeds).  
(43) An organism is ‘regulated’ by MPI if it could cause unacceptable consequences (i.e. likely to cause unacceptable economic, environmental, soc io-cultural or human health impacts in New 
Zealand) if it were to enter and establish in New Zealand, provided the organism is:  
a) Not present in New Zealand; or  
b) If present in New Zealand is under official control ; and  
10 c) Is able to establish and spread in New Zealand.  
(44) Organisms that are present in New Zealand may also be regulated,  when found in association 
with imported goods, if they are known vectors of regulated pest s.  
(45) When managing biosecurity risks associated with plants for planting a period of time may  be 
required to examine plants for  signs and symptoms of regulated pests, or to complete specific 
testing, before plants can be cleared for entry into New Zealand. Therefore, if specified in an 
import health standard, plants for planting must  be screened in quarantine to ensure that they are 
free from regulated pest s. An import health standard may allow such screening to be done either 
offshore, or after th e plants arrive in New Zealand.  
(46) MPI monitors the pathway performance related to each import health st andard to ensure 
biosecurity risks are effectively managed . This is achieved through verification and inspection 
activities at the border and, where necessary, audits of offshore production systems.  
(47) MPI is committed to the principles of transparency and evidence- based technical justification for 
all new and amended phytosanitary measures  imposed on importing pathways.  
 International  
(48) Where possible, phytosanitary import requirements are aligned with international standards, guidelines, and recommendations
1 as per New Zealand’s obligations under Article 3.1 of the 
World Trade Organisation (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures; WTO, 1995 (SPS Agreement).  
(49) The SPS Agreement sets in place rules that protect each country’s soverei gn right to take the 
measures necessary to protect the life or health of its people, animals, and plants while at the 
same time facilitating trade. It embodies and promotes the use of science- based risk 
assessments to manage the risks associated with the i nternational movement of goods.  
(50) In keeping with New Zealand’s obligations under the SPS Agreement and the IPPC (International 
Plant Protection Convention ), phytosanitary measures must:  
a) Be scientifically justified and only for regulated pests. The strength of any phytosanitary 
measure will depend on an  assessment of risk, with an emphasis on the consequences of 
the pest establishing in New Zealand;  
b) Not discriminate unfairly between countries or between imported and domestically produced 
goods;  
c) Not be more tr ade restrictive than necessary ; 
d) Be based on international standards wherever possible, but WTO members can adopt a 
measure that is more stringent than an international standard, provided the measure is 
scientifically justified.  
 Strength of measures 
(51) Measures are required for regulated pests where the ‘probability of introduction (entry and 
establishment) and spread’ on a pathway is unacceptable (i.e. if a regulated pest  is able to enter 
through the pathway, find a suitable host, and establish and spread in New Zealand).  For plants 
for planting proposed for import, the probability of entry  is difficult to assess  because the IHS 
covers a wide diversity of material  from all  countries , including that from commercial facilities with 
established pest management practices as well as wild -collected plants. However the strength of 
                                                           
 
1 Note that international standards, guidelines or recommendations referred to in the WTO agreement are those of Codex, OIE (World Organisation for 
Animal Health) and the IPPC.   
11 association  is noted  in the commodity assoc iation section of the risk analysis and can be taken 
into account in the decision.  Exposure (transfer to a suitable environment) is assessed as a high 
likelihood for all associated regulated pests based on previous import risk analyses for plants for 
planting.   
(52) Risk is an assessment of both likelihood (of establi shment) and consequence (impact). While 
measures can only reduce the likelihood of establishment (i .e. do not affect consequence), t he 
greater the risk posed by a pest that will establish and cause unwanted harm, the greater the 
level of assurance MPI requ ires that the pest is managed in a consignment.  The required strength 
of a measure depends on the risk posed by a particular regulated pest  on a particular pathway  
and is  determined by a combination of the consequences the pest may cause if it was introduc ed 
into New Zealand and the likelihood that the pest will enter and establish from a pathway.   
(53) Plants for planting  is one of the high est risk pathway s for the introduction of pests and diseases to 
new areas  (for example as per ISPM 32: Categorisation of commodities according to their pest 
risk). Part of the reason for this is that plant pests can survive in living plant material that does not 
show any signs of infection/infestation , and the living plant material increases the likelihood of 
pest survival and hence the likelihood of introduction. Because plants imported for planting may 
be multiplied and/or widely distributed throughout the country , including in key areas of 
commercial production, the likelihood of pests surviving and being transferred to suitable  
domestic hosts is higher than for many other import pathways. This is why, if required in an 
import health standard, plants for planting  must be screened for regulated pests before they are 
cleared for entry into New Zealand.  
   
12 3. Risk management approach  
(54) This Part of the risk management proposal includes a description of the information used to 
develop the draft standard, and describes the types of risk management measures that may be 
applied to plants for planting that are imported into New Zealan d. 
 Source information 
(55) This risk management proposal is based on information in the MPI risk analysis: budwood/ dormant cuttings of Prunus  spp.. Where information has been used that is not included in the risk 
analysis, citations are given as footnotes to this risk management proposal . 
 Risk management measures 
(56) Risk management measures that are  considered when developing an import health standard for 
plants for planting are discussed in this section. These measures can be applied either before  
export (i.e. p re-border) or at the New Zealand border  (including in post entry quarantine) . 
(57) Because plants for planting present a high biosecurity risk  (as noted in paragraph (53) ), greater 
emphasis is put into measures that are applied at the border (including post entry quarantine) than for other commodity types  (e.g. fresh produce for consumption) . Reasons for this include the 
following (taken from ISPM 36 : Integrated measures  for plants for planting):  
a) Some pests do not cause distinct visual symptoms, particularly at low pest incidence;  
b) Symptoms of infestation may be latent or masked at the time of inspection (e.g. as a result 
of pesticide use, nutrient imbalances, dormancy of plants at time of dispatch, presence of 
other non- regulated pests or by removal of symptomatic leaves);  
c) Small insects or eggs may be hidden under bark or scales of buds etc.;  
d) The type of packaging, size and physical state of the consignment can influence t he 
effectiveness of inspection;  
e) Detection methods for many pests, particularly pathogens, may not be available.  
3.2.1 Pre-border measures  
(58) Generic  pre-border risk management measures that may be applied include:  
a) Commercial production to reduce pest prevalence;  
b) Treatment for regulated insects  and mites;  
c) Official pre -export inspection and phytosanitary certification by the NPPO of the exporting 
country  to verify that pre- export measures have been undertaken and were effective , and 
that the consignment is free from visibly detectable regulated pests . 
(59) As well as  the generic risk management measures , specific measures may  be applied  offshore to 
manage risk associated with some, or all regulated pests that may be associated with plants for 
planting.  
a) The option for measur es to be applied offshore is included in Part 1. 6 of the draft standard, 
which allows Prunus  plants for planting to be produced according to an Export Plan, or at an 
Offshore Facility (see Parts 3.2.1.1 and 3.2.1.2  of this risk management proposal ). 
b) When specific measures are applied offshore, the plants for planting are likely to  have fewer 
requirements for screening for regulated pests on arrival in New Zealand :  
13 i. This can be advantageous to importers because plants may be able to be held in a 
lower level of quarantine facility on arrival in New Zealand, and/or have a shorter 
quarantine period (in recognition of measures that are applied offshore). This may result in lower import costs  and more rapid clearance of goods.  
ii. The requirements for screening for regulated pests on arrival i n New Zealand, along 
with the level of post entry quarantine and the length of the quarantine  period will 
depend on the number and type of phytosanitary measures that are  applied offshore;  
iii. These measures will be evaluated when an Export Plan  is agreed, or when an Offshore 
Facility  is approved;  
iv. Phytosanitary measures  that must be applied in New Zealand will be identified in the 
import permit for each consignment  (as discussed in Part 5.1
 of this risk management 
proposal ). 
(60) Audit testing may be required after plants arrive in New Zealand to verify the effective application of phytosanitary measures  that were applied prior to export . If audit testing is required, plants may 
need to be held in post entry quarantine until testing is completed. Any audit testing requirements will be identified when MPI agrees on an Export Plan  or approves an Offshore Facility . 
3.2.1.1  Production according to an Export Plan  
(61) An Export Plan is an agreement between MPI and the NPPO of the exporting country  that 
describes all activities that support the effective application of phytosanitary  measures that are 
applied prior to export.  
a) An Export Plan will not be agreed upon until a CTO is satisfied that it  meets New Zealand’s 
expectations for biosecurity;  
b) An Export Plan must be agreed before imports can commence;  
c) Any countries with an Export Plan  for Prunus  plants for planting will be identified in  the MPI  
online system ; 
d) There are no Export Plans  in place for Prunus  plants for planting at the time of writing this 
risk management proposal.  
(62) A combination of the following measures may be included in an Export Plan  to manage 
biosecurity risk associated with some, or all, of t he regulated pests associated with Prunus  plants 
for planting:  
a) Country freedom , where a CTO  is satisfied that a country has country freedom status in 
relation to a particular pest. To ensure country freedom, measures described in ISPM 8: 
Determination of pest status in an area  and ISPM 4: Requirements for the establishment of 
pest free areas  must be applied by the exporting country ; 
b) Production in a pest free area, using systems to establish and maintain freedom as 
described in ISPM 4: Requirements for the establishment of pest free areas ; 
c) Pest free place of  production under the supervision of the NPPO of the exporting country, as 
described in ISPM 10: Requirements for the establishment of pest free places of production and pest free production sites ; 
d) The use of Integrated measures for plants for planting under the supervision of the NPPO of 
the exporting country, as described in ISPM 36:  Integrated measures for plants for planting . 
3.2.1.2  Production in an MPI approved offshore facility : 
(63) MPI can approve an Offshore Facility  to undertake some (or all) of the testing  for regulated pests 
that would otherwise be done in post entry quarantine in New Zealand;   
14 (64) Offshore facilities must be accredited to the MPI Standard PIT -OS-TRA-ACPQF: Accreditation of 
Offshore Plant Quarantine Facilities and Operators . Note that  this standard is currently under 
review and MPI expects to consult on a revised version soon ; 
(65) More information about offshore facilities can be found on the MPI website at 
http://mpi.govt.nz/news -and-resources/resources/registers -and-lists/offshore/ . 
3.2.2 Measures and verification activities at the border 
(66) Measures and verification activities undertaken at the border include:  
a) Inspecting  documents to verify that the phyt osanitary certificate , and other associated 
documents, comply with the requirements of the standard;  
b) Inspecting  plants  at the place of first arrival  to verify freedom from visible  pests . For 
horticultural crops,  it is expected that all plants will be inspected on arrival at the border ; 
c) Remedial action (for example treatment) if a regulated pest is detected during the on-arrival 
inspection, or if any required treatments were not applied prior to export;  
d) Screening plants in post entry quarantine, using  some or all of the following measures:  
i. Inspecting  for signs and symptoms of regulated pests;  
ii. Diagnostic testing to verify whether a regulated pest is present in plants showing signs 
or symptoms of diseases;  
iii. Grow ing pl ants under environmental conditions conducive to disease development  (see 
part 3.2.2.1 ); 
iv. Mandatory  testing  (for example using biological indexing, microbial culturing, or 
polymerase chain reaction [PCR])  to detect asymptomatic regulated pests . 
(67) The following factors are  considered when determining the disease screening measures that will 
be applied, the length of the quarantine period, and/or  the type of post entry quarantine facility in 
which the plants must be held:  
a) Likelihood of entry of a regulated pest on a particular  import pathway:  
i. Whether a particular regulated pest is likely to be associated with the plant parts being 
imported (for ex ample tissue cultures vs. cuttings  vs. whole plants);  
ii. Presence or absence of the quarantine pest in the exporting country  (for example if a 
CTO is satisfied that a country has country freedom status in relation to a particular pest  
and this can be endorsed on a phytosanitary certificate in accordance with the relevant 
ISPM ); 
iii. Whether material is produced under an Export Plan  or at an Offshore Facility ; 
iv. Available treatment methods (for example insecticide or miticide  before plants enter 
quarantine).  
b) Pathogen biology:  
i. Mode of transmission;  
ii. Whether vectors are present (or likely to be present) in New Zealand;  
iii. Whether vectors are likely to be present in close proximity to the quarantine facility;  
iv. Whether the same (or related) species as the imported plants , or ot her known host 
species,  are likely to be present in close proximity to the quarantine facility ; 
v. Epidemiological characteristics .  
15 c) Available disease screening methods (for example growing season inspection, biological 
indexing, PCR);  
d) Likelihood of establishment of a quarantine pest via an import pathway;  
e) Potential environmental , economic , human health and /or socio -cultural consequences  of 
establishment.  
3.2.2.1  Risk management options  for bacteria, fungi  and oomycetes in post entry quarantine  
(68) When developing  new import requirements for Prunus plants for planting, MPI considered 
whether similar measures  to those in the existing standard will manage risk from bacteria, fungi 
and oomycetes to an appropriate level , or whether alternative measures could be applied to 
provide a higher level of  risk management . 
(69) Risk management options for bacteria, fungi and oomycetes were considered in detail here 
because, under the existing import health standard,  these classes of organism generally have  
less stringent disease scr eening requirements  in post entry quarantine than other classes of 
regulated pest (such as phytoplasmas, viroids and viruses) . This means  that the level of 
protection may be inconsistent between different classes of regulated pest . Three risk 
management options were considered, as follows:  
a) Maintaining the status quo, with similar measures  to those in the existing Prunus standard;  
b) Applying specific environmental conditions in post entry quarantine to increase the likelihood of detecting various  regulated p ests; 
c) Maintaining the status quo, but with more comprehensive mandatory testing requirements . 
(70) The risk management options  identified above are discussed in the following sections . Specific 
measures proposed for Prunus plants for planting  are described in P art 4
 of this risk management 
proposal . 
(71) Risk management options for other classes of regulated pest ( for example including 
phytoplasmas, viroids and viruses) have not been considered in this part of  the risk management 
proposal. This is because,  for these classes of organism , existing measures are considered to 
manage the risk  to an appropriate level (as discussed elsewhere in this risk management 
proposal ). 
(72) Taking into consideration information in t he following sections, MPI is seeking specific feedback 
on the following:  
a) Whether existing risk management measures for bacteria, fungi and oomycetes  (as 
described in Part 3.2.2.1.1 ) manage risk to an appropriate level . 
When considering this, it is noted that there is no evidence of any regulated pest incursions in New Zealand being attributed to imports of plants for planting imported under  measures  in 
the existing Import health standard for importation of nursery stock
; 
b) If existing measures do not manage risk to an appropriate level, what alternative measures 
should be considered to achieve a higher level of risk management . 
When considering the alternative options identified in Parts 3.2.2.1.2 and 3.2.2.1.3 , 
feasibility and cost may need to be taken into account. In addition to options presented here, 
MPI will welcome any alternative suggestions on how risk associated with bacteria, fungi 
and oom ycetes could be managed in a way that will provide a level of protection consistent 
with that for other regulated pests . 
(73) It is very important to note that the level of protection established for Prunus plants for planting  is 
likely to  be applied when MPI reviews import requirements for other genera of plants for planting 
that have a similar risk profile to Prunus (for example including other high value crop species). As  
16 such, MPI is seeking feedback on this matter from all interested stakeholder groups, and not just 
those directly affected by the proposal for Prunus plants for planting . 
3.2.2.1.1  Option 1: Maintaining the status quo 
(74) Since the existing Prunus import schedule was issued in 2004, risk associated with bacteria, fungi 
and oomycetes has been managed predomi nantly by a requirement for plants to be regularly 
inspected throughout the post entry quarantine period in New Zealand . 
a) Under the existing standard, all plants must be inspected for signs of pest s and disease by 
the operator of the post entry quarantine facility at least twice per week during periods of 
active growth and once per week during dormancy. Plants are also inspected a minimum of 
five times by an MPI inspector  over the duration of the quarantine period.  Whilst in 
quarantine, Prunus plants for planting imported into New Zealand are generally contained in 
greenhouses with limited climate control, and plants are maintained under conditions 
cons idered optimal for plant growth;  
b) Three particular ly high risk pests  of Prunus  (i.e. Ceratocystis spp., Phytophthora ramorum 
and X. fastidiosa)  also require testing by PCR and/or plating of samples  on suitable isolation 
medium . Additional m easures for C eratocystis spp. and P. ramorum were  introduced within 
the las t five years, with  reliance on growing season inspection before that . Testing 
requirements for X. fastidiosa have been in place since the standard was issued in 2004;  
c) The existing standard also requires asymptomatic leaf samples from each imported plant to 
be plated on potato dextrose agar to help manage risk from regulated fungi. Culture -based 
detection using leaf samples taken from healthy plants is now considered unlikely to be an 
effective detection technique. This method is not propose d as a risk management measure 
in the revised standard, for the following reasons:  
i. Culturing using a generic culture medium (such as potato dextrose agar) may reveal the 
presence of a particular organism, or class of organi sm within an asymptomatic plant. 
However , this does not provide any information about whether that organism is 
pathogenic towards a particular host species;  
ii. Culturing generally has low specificity and sensitivity and c an produce inconclusive 
results:  
- When culturing samples taken from asymptomati c plants in post entry 
quarantine, staff at the MPI Plant Health and Environment Laboratory (PHEL) 
have mainly isolated endophytic or saprophytic organisms. These organisms are 
ubiquitous, relatively unstudied and extremely diverse, often meaning that it i s 
not possible to identify to the species level;  
- These ubiquitous  types of organism would not meet the definition of a quarantine 
pest as defined under ISPM 5: Glossary of phytosanitary terms . As such, when 
used for mandatory testing on asymptomatic samples, culturing is now seen as 
being of very  limited value when making regulatory decisions;  
- Culturing will not effectively detect regulated pests that are un- culturable and/or 
very slow growing, or that are not suited to grow ing on generic culture media.  
iii. Culturing leaf samples will not detect regulate d pests  growing in woody parts of the 
plant , and vice versa ; 
iv. False negative results will be obtained if regulated fungi or oomycetes are unevenly 
distributed throughout the plant and are not contained within t he sample selected for 
testing  (as is the case with any diagnostic test) .  
17 (75) There are no known instances of any regulated pests being introduced to New Zealand in Prunus 
plants imported according to the requirements of the existing standard, and no records of any major  bacterial, fungal or oomycete regulated pests being detected on Prunus  plants in 
quarantine  in New Zealand . 
a) As noted in paragraph (26) , all imported Prunus plants for planting over the past ten years 
have  been from MPI -accredited sources. Plants obtained from approved sources are grown 
in screenhouses at the pre- export production site and are regularly inspected for signs of 
disease  prior to export . Fungicide treatments are applied if symptoms of fungal disease are 
identified and/or as part of a regular fungicide spray programme (depending on the particular production facility). Aside from that, specific measures are not generally applied to 
manage risk from regulated fungi prior to export.  Some offshore facilities explicitly state that 
plants they produce are not guaranteed to be free of fungi ( or other pests ). 
(76) Based on the above  information, existing risk management measures may be seen as being 
appropriate to manage risk on this pathway , particularly for Prunus  sourced from MPI -approved 
offshore facilities , given the long history of trade and compliant consignments.  
a) It is noted that using  growing season inspection as the sole method to manage risk from 
most bacteria, fungi and oomycetes is not as sensitive as methods used to detect other 
regulated pests of Prunus  that may have a similar adverse impact on plant health. Likewise, 
this method is less sensitive than techniques proposed to detect regulat ed pests with a 
similar risk profile on other plant genera (such as Actinidia ), as described in the following 
section ). 
3.2.2.1.2  Option 2: Applying s pecific environmental conditions in post entry 
quarantine  
(77) MPI has recently proposed new measures, focussed on growing plants under conditions known 
to be conducive to disease development, to better manage risk from various classes of regulated 
pest including bacteria, fungi, oomycetes and viroids that may otherwi se be difficult to detect. 
These measures were  proposed for  both Actinidia  (as per the import health standard published in 
2018) and Citrus (measures proposed in 2016, but not yet adopted
2). As discussed in the 
following sections, this option will provide a higher level of protection than existing measures, but 
is likely to result in more cost to importers and may take some time to implement.  
a) Growing plants under conditions conducive to disease development is listed as a general requirement that may be consi dered for post entry quarantine facilities in ISPM 34: Design 
and operation of post -entry quarantine stations for plants , and is recognised as a risk 
management measure in ISPM 36: Integrated measures for plants for planting;  
b) This measure was recommended f or further investigation in a report to the Germplasm 
Advisory Committee (Germac) in 2011,  as summarised by Johnson (2014)
3, to increase the 
possibility of detecting regulated pests  that may be present on imported plant material  and 
to further reduce overall biosecurity risk ; 
c) In 2018 MPI proposed growing Actinidia plants for planting4 under conditions conducive to 
disease development to help manage biosecurity risk from certain classes of regulated pest 
including high risk bacteria, fungi and oomycetes. Thi s included regulated pests such as 
                                                           
 
2 2 Risk management proposal for Citrus nursery stock available at https://www.mpi.govt.nz/dmsdocument/14137 -risk-management -proposal -import -health-
standard- ihs-155-02-06-importation -of-nursery -stock- schedule- of-special -conditions -for-citrus -including- citrus -fortunella -and-ponc irus-from-all-countries -
draft- for-consultation . This import health standard has not yet been re- issued.  
3 Johnson, N. (2014). Barriers to importation of plant germplasm. https://www.mpi.govt.nz/dmsdocument/6949 -barriers -to-importation -of-plant -germplasm . 
4 Import health standard for Actinidia plants for planting available at https://www.biosecurity.govt.nz/document -vault/29894 .  
18 Pseudomonas syringae pv . actinidiae (Psa), Ceratocystis fimbriata  and Phytophthora spp. 
The measures include growing plants at 21°C to 25°C and 25°C to 30°C with high humidity 
(70-80%), because these conditions are known to be conducive to development and/or 
symptom expression of multiple regulated pests, including those listed above. Likewise, 
under the proposed new import health standard for Citrus plants for planting5, that has not 
yet been issued, imported Citrus  plants must be grown at 18°C to 25°C for 5 months and 
28°C to 32°C for 3 months, to increase the likelihood of detecting various Liberibacter  and 
viroid species.  
(78) Growing plants under  conditions conducive to disease development is likely to  provide a higher 
level of protection for various species of regulated bacteria, fungi and oomycetes  on Prunus 
plants for planting because:  
a) Symptoms are more likely to become visible  on plants that ar e infected with regulated pests  
when plants are grown under conditions suitable for disease development : 
i. Disease development usually occurs when environmental conditions favour 
development of the pathogen (for example as discussed in Agrios, 20056 and Moore et 
al., 20117); 
ii. Disease s ymptoms are much less likely to  develop when conditions are optimal for 
plant growth6,7; 
iii. Conditions known to be conducive for disease development for certain regulated 
bacteria, fungi and oomycetes on Prunus plants for planting are identified in Parts 4.3.1  
and 4.3.2  of this document.  
b) Even if symptoms do not become visible, growing plants under conditions conducive to 
disease  development is likely to increase the pathogen titre and hence increase the 
likelihood of detection by other methods  (for example when using PCR to detect  pathogens 
that require mandatory testing) ; 
c) Growing plants under conditions  that are  known to be conducive to development of a wide  
range of pathogens is more likely to  result in symptom expression from  any unknown or 
emerging regulated pests for which specific diagnostic tests are not available.  As such, 
there will be more effective management of unknown risk.  
(79) Examples of high impact regulated pests associated with Prun us plants for planting  that are likely 
to be more effectively managed by growing plants under defined environmental conditions include Phytophthora spp., Spiroplasma citri , and X. fastidiosa.  Other regulated pests  are also considered 
more likely to display  symptoms under such conditions, as noted in Part s 4.3.1 and 4.3.2
 of this 
document.  This approach is also considered more likely to result in the detection of regulated 
pests of Prunus  that are not specifically identified in the standard, and for which the only required 
risk management measure is plant health inspections throughout the quarantine period.  
(80) The approach described above would represent a change in the level of protection from certain 
species of bacteria, fungi and oomycetes  associated with Prunus plants for planting . This will 
more closely align the level of protection for these types of organism with that for other pests  
regulated by MPI , including those with a high impact  (for example including phytoplasmas and 
various species of viroid and virus ). 
                                                           
 
5 Risk management proposal for Citrus nursery stock available at https://www.mpi.govt.nz/dmsdocument/14137 -risk-management -proposal -import -health -
standard- ihs-155-02-06-importation -of-nursery -stock- schedule- of-special -conditions -for-citrus -including- citrus -fortunella -and-poncirus -from-all-countries -
draft- for-consultation . This import health standard has not yet been re- issued.  
6  Agrios, G.N., 2005. Plant Pathology. 5th eds. Department of Plant Pathology. University of Florida. United States of America.   
7 Moore, D., Robson, G.D. & Trinci, A.P.J. (2011). 21st Century Guidebook to Fungi . Cambridge, UK: Cambridge University Press.   
19 a) A similar level of protection should be required for different classes of regulated pest that are 
likely to have a similar environmental and/or economic impact, where  this is feasible;  
b) Different plant genera may have a similar risk profile, and may be infected by the same 
regulated pests, or genera of regulated pests . In such cases, a similar  level of protection 
should be provided across different genera  of plants for planting. The approach described 
above will help to ensure that this is the case because:  
i. The proposed screening is consistent with measures recently consulted on for the new 
import health standard for Actinidia plants for planting  to manage risk from various 
bacteria, fungi, oomycetes and viruses ; 
ii. The proposed screening is similar to measures proposed in 2016 (but not yet adopted) 
to manage risk from temperature sensitive bacteria on  Citrus plants for planting;  
iii. The proposed screening is more consistent with existing requirements for detecting 
regulated phytoplasmas, viroids and viruses  on high value crops , where samples for 
PCR testing must be collected when plants have been grown under seasonal  conditions 
known to be optimal for pathogen development . 
(81) The level of risk from regulated bacteria,  fungi and oomycetes on the plants for planting pathway 
has not necessarily changed since the Prunus , and  other nursery stock import schedules , were 
original ly issued. However, there is now recognition that measures applied prior to export, and in 
post entr y quarantine in New Zealand,  may not give the desired level of protection for  this 
commodity type.  This proposed approach takes into account the greater recognition , by industry 
and government organisations, of the threat posed by regulated pests such as  the Ceratocystis 
and Phytophthora genera  (both of which are associated with Prunus  plants for planting), and 
regulated pests in general, since the Prunus  schedule last underwent significant revision (in 
2004).  
(82) MPI recognises that there may be operational im plications if such measures  are applied in post 
entry quarantine, as discussed below:  
a) The proposed conditions  may encourage the growth of non- regulated pests , either of local 
origin  or introduced in association with the imported plants. This may result in increased 
costs, for example if these organisms need to be identified by a diagnostic facility and/or if 
treatments must be applied to symptomatic plants.  However:  
i. When plants are contained in a Level 3B post entry  quarantine greenhouse, 
contamination with local origin organisms in the first growing season will be minimised 
because all incoming air must be filtered through fine dust filters (which will exclude 
most , or all,  disease propagules);  
ii. MPI has discussed possible impacts of the proposed measures on plant health with 
staff who operate the Australian government post entry quarantine greenhouse. Similar 
environmental conditions are required for plant genera including Actinidia and Prunus  
imported into Australia, where plants must be grown at high humidi ty for at least six 
weeks (for example at temperatures between 19°C to 25°C)  on arrival at the facility . 
These conditions have not caused any significant increase in symptoms from non-regulated pests, or had a significant adverse impact on plant health on plants at the 
Australian Mickleham facility. However, this facility has  been constructed in a way that 
will minimise adverse effects on plant health (e.g. by having high ceilings and high air 
exchange rates). This may not be the case in an existing greenhou se that was not 
designed with a view to applying such environmental conditions . 
b) While it remains possible that the environmental requirements may have some  adverse 
effect on plant health, growing plants under conditions  conducive to regulated pest 
development will be an important measure to help ensure that imported germplasm is free  
20 from regulated pests . This is particularly important when growing season inspection is the 
sole method used to screen for disease , given that symptoms  may not develop when plants 
are grown under conditions optimal for plant growth;  
c) Although there may be increased costs associated with applying such conditions, if the 
requirement for mandatory testing by plating leaf samples on agar is removed, this will  
remove some costs associated with importing plants under the existing Prunus standard.  
These testing costs can be considerable if fungi are isolated that require DNA sequence 
analysis to identify them;  
d) Because the environmental conditions may not be optim al for plant growth, an extra period 
of growth may be needed  during the first growing season to develop plants to a stage where 
this treatment will not have an unacceptable adverse effect on plant health, or to allow resumption of growth after the conditio ns have been applied;  
e) It is noted that additional  plants , derived from  plants that will be  exposed to the specified 
environmental conditions , can be multiplied during the quarantine period. These plants 
would not need to be grown under the conditions speci fied in the draft standard . As such, if 
desired by the importer, imported material can be grown under conditions optimal for plant 
growth whilst the parental material is being screened for disease. These plants would need 
to be held in the same type of pos t entry quarantine facility as the parental material, and 
would become eligible for biosecurity clearance at the same time as parental plants. It is noted that  there may be barriers, or higher costs to taking this approach, if additional 
quarantine greenhouse space is needed;  
f) Additional equipment  (e.g. fogging systems)  may be needed to effectively maintain high 
humidity  and temperature regimes  in existing greenhouses . There is a greater load on 
heating systems at high humidity (because increasing humidity h as a cooling effect ). This 
means that existing HVAC  systems may struggle to maintain the proposed conditions , and 
more significant changes may need to be made to facility infrastructure to reliably apply such conditions to plants in post entry quarantine on an ongoing basis.   
(83) Based on the  above information, under  this risk management option, a prolonged lead in time 
may be needed to allow facilities to implement the new requirements . If introduced with 
immediate effect this would present a barrier to impor t because, based on conversations with 
staff from post entry quarantine facilities in New Zealand, MPI is not aware of any existing facilities who would be able to apply the proposed high humidity regime without making changes 
to the facility structure. Th ere may be considerable capital costs to upgrade existing facilities to a 
level where they could reliably apply the proposed conditions. Given the long term nature of 
bookings at post entry quarantine facilities, sufficient time will also need to be given  to allow 
facilities to implement such changes without significantly impacting day -to-day operations.  
(84) Taking into account the above information it is suggested that  if this proposal is adopted  there 
should be a staged implementation. As an interim option,  imported Prunus plants for planting 
could be held at the required temperature ranges from the time the import health standard takes 
effect, but the proposed humidity requirements could become mandatory at  a later date.  
a) Holding plants at the required temperature ranges is likely to result in more effective 
management of some high risk regulated pests (for example including S. citri and X. 
fastidiosa) . There are some existing post entry quarantine facilities that would be able to 
apply these conditions without any need for facility modification;  
b) Because of t he potential significant costs and logistical implications associated with 
upgrading a facility it is proposed that under this option, a three year  lead- in time should be 
given before compliance with the proposed humidity regimes is mandatory. This is considered appropriate in the case of Prunus plants for planting given the long history of 
trade under existing import conditions .   
21 3.2.2.1.3  Option 3: Maintaining the  status quo, with more comprehensive testing 
requirements  and no requirement for plating on agar   
(85) In addition to growing season inspection as required under the existing standard (i.e. without 
manipulating environmental conditions) , additional PCR testing  could be done  to provide further 
assurance that certain regulated pests are not present in imported plants. This could apply to 
particularly high risk regulated pests, as well as regulated pests where there is evidence that symptoms may not develop unless plants are exposed to specific climatic conditions.  
(86) Relying solely on PCR testing of asymptomatic material  taken from plants growing in post entry 
quarantine  may not effectively manage risk from all bacteria, fungi and oomycetes because:  
a) It may not be poss ible to collect representative samples for testing, especially when 
asymptomatic plants are tested. This is because pests such as fungi and oomycetes may have a restricted distribution within an infected plant. False negative results will be obtained 
if pests are unevenly distributed throughout the plant and not contained within the sample(s) 
selected for testing;  
b) Although PCR can be highly sensitive and specific, and is likely to be more sensitive and 
specific than culturing, it still relies on the target pest being present in the sample selected 
for testing , and at levels high enough to be reliably detected;  
c) This is in contrast to when PCR is used to test for organisms such as phytoplasmas and 
viruses that are likely to be systemically distributed throughout a plant , or where there is 
specific epidemiological information about sampling strategies that can be  used  to provide a 
very high degree of certainty that a particular pest is absent . This is precisely why greater 
reliance is placed on growing season inspections for detecting fungi and oomycetes than for detecting some other classes of organism ; 
d) Given the large number of regulated fungi associated with Prunus plants for planting, it 
would not be possible to test plants growing in post entry quarantine for all regulated 
species. As such, there will still be reliance on growing season inspection to manage risk from many species.  
(87) To increase the likelihood of detecting some regulated pests , in addition to testing  samples from 
plants growing in post entry quarantine, destructive sampling and PCR testing  could be done 
using the originally imported budsticks  (which are discarded after buds are grafted onto 
rootstocks in post entry quarantine).  
a) Destructively testing the originally imported stem material  (once buds have been grafted 
onto local origin rootstocks)  may allow for  more representative sampling of imported 
material . This could  help give greater certainty of freedom from targeted regulated pests ; 
i. The testing would be used to provide greater certainty that regulated pests that may have an uneven distribution, and that may be difficult to reliably detect in asymptomatic 
samples, are not present in imported material . Additional destructive testing would not 
be used to test for regulated pests that are likely  to be systemic and /or reliably detected 
using samples taken from plants growing in post entry quarantine.  
ii. It would not be feasible to do PCR testing for all regulated pests that may be present on 
Prunus plants for planting, in particular given the large number of regulated fungi that 
may be associated with this commodity . This measure would need to be targeted at 
particularly high risk pests, and/or other regulated pests where there is evidence that 
growing season inspection in post entry quarantine may not be reliable. Growing season inspection, as required under the existing import health standard (discussed in 
Part 3.2.2.1.1
), would still be used  to manage risk from regulated pests with no 
requirement for specific testing;   
22 iii. This type of testing would be only useful for detecting wood- inhabiting regulated pests 
(for example including Ceratocystis spp. and Phytophthora spp.). Regulated pests such 
as bacteria, that tend to be located in bud tissue, w ould not reliably be detected using 
this approach.  
b) Validated PCR  diagnostic tests may not be available for all regulated pests for which testing 
is needed under this option. Hence a lead in time may be necessary to allow tests to be 
developed,  and funding and resources would need to be provided to develop the tests.  
(88) As well as needing to develop new tests,  sampling methods will need reviewing to ensure the 
maximised likelihood of detecting target regulated pests if they are present in imported plants. 
The most suitable tissue type and sampling regime should be decided for each regulated pest for which testing is needed . 
(89) If this o ption is chosen , in order to allow ongoing trade, there will need to be a staged 
implementation with additional tests added as they become available. Introduction of additional tests will depend on resource being set aside to prioritise developing these tests . As such, there 
may be a considerable delay before all necessary tests could be introduced.   
  
23 4. Proposed risk  management  measures for Prunus  plants for 
planting  
(90) This section  of the risk management proposal  includes the following:  
a) A description of the proposed requirements for screening  for regulated pests ; 
b) A description of the proposed requirements for  post entry quarantine including the length of 
the quarantine period and the level of post entry quarantine greenhouse required for Prunus  
plants for pla nting ; 
c) A summary of all regulated pests  for which specific phytosanitary measures are proposed, 
and a description of the disease screening measure( s) that are proposed for each pest.  
(91) All phytosanitary measures described in this section  must be applied in New Zealand unless  
plants are produced under an Export Plan or at an Offshore Facility . Plants that are produced 
using one of these options  will have fewer requirements on arrival in New Zealand  because 
some, or all of the required measures will have been applied prior to export . 
(92) For each consignment of Prunus  plants for planting, the phytosanitary measures that  need to be 
applied in New Zealand will be identified on the import permit , as discussed in Part 5.1 of this risk 
management proposal . 
 Proposed requirements for screening for regulated pests  
(93) All Prunus  plants for planting will be screened for regulated pests as described in Part 2.3 of the 
draft standard.  Proposed s creening will consist of  a combination of some or all of the following 
measures, depending on the characteristics of the regulated pest : 
a) Regular plant health inspections to detect any signs or symptoms of regulated pests;  
b) Exposing plants to specific environmental conditions conducive to disease development;  
c) Specific testing (for example using polymerase chain reaction (PCR) or culture based 
identification for the targeted detect ion of specified regulated pests ). 
4.1.1 Environmental conditions  
(94) Taking into account information in part 3.2.2.1  of this risk management proposal,  and based on 
information about specific regulated pests  in Part 4.3, it is proposed that Prunus plants imported 
into New Zealand should be exposed to specific environmental conditions that will increase the likelihood of detecting regulated pests  either directly (by inducing expression of visible disease 
symptoms), or indirectly (by increasing the titre of an organism before samples are taken for pre-determined testing).  
a) As noted in paragraph (72)  MPI is seeking specific feedback on risk management options 
for bacteria, fungi and oomycetes. Based on existing information, the option which MPI 
consider s will provide a level of protection consistent with the level achieved for other 
classes of regulated pest (i.e. the highest level of protection) is proposed for inclusion in the standard. However, the MPI Chief Technical Officer  (CTO) will consider all information 
provided in submissions  before finalising risk management requirements for these regulated 
pests. This means that measures in the final draft standard may  differ to those proposed 
below;  
b) Proposed conditions , described in the following sections , are included in part 2.3.1 of the 
draft standard;   
24 c) MPI recognises that i t may not be operationally feasible for  any existing post entry 
quarantine facilit ies to apply all conditions identified below with immediate effect . In 
particular this applies to growing plants under high humidity, which may be difficult to do  if 
facilities were not built with this  purpose in mind. Because of this  it is proposed that an  
implementation period should apply . The implementation period will apply only to the 
requirement for plants to be held at high relative humidity ; all other conditions  described 
below  will be expected to be applied from the  date the standard is issued. As discussed 
elsewhere in this risk management proposal, an implementat ion period of three years is 
proposed.  
(95) Post entry quarantine facility operators  will be required to describe how the proposed conditions 
will be applied in the operating manual for each facility, and to maintain records demonstrating 
compliance with the co nditions described in the standard.  
4.1.1.1  Spring- like conditions for three  or four  months  
(96) At the start of the first growing season8, plants must be held for four  months at a daytime 
temperature range between 18°C and 21°C and night time temperatures below 18°C. At the start 
of the second growing season, plants must be held under these conditions for a minimum of three 
months.  
(97) This temperature range is generally considered conducive to the detection of viral diseases 
(either directly when symptoms are expressed, or indirectly by testing using PCR or herbaceous 
indicator plants; see Part 4.3.4 ), given that spring is the optimal time for viral replication.  
(98) The four month period under spring- like conditions  at the start of the first growing season will be 
long enough to ensure that there is sufficient plant growth to enable the first batch of samples to be taken for mandatory testing (see Part 4.1.3
). This is reduced to three months in the second 
growing season because this is considered long enough for sufficient quantities of leaf material to 
become available for mandatory testing.  
4.1.1.2  Sum mer- like conditions for four months  
(99) Following the spring- like conditions, plants must be held for four months at a daytime temperature 
range between 21°C and 25 °C and night time temperatures above  18°C (except when plants are 
being held as described in paragraph (100) ). 
a) These conditions are expected to be broadly conducive to symptom development of certain 
fungal , oomycete and bacterial  diseases. As d iscussed in paragraph (74), it is proposed that 
this requirement will replace the existing requirement for leaf samples to be plated on potato 
dextrose agar (to detect regulated fungi). Summer- like conditions  will also provide conditions 
suitable for maximising the likelihood of detecting phytoplasmas and viroids.  
(100) During the summer -like period in the first growing season, it is proposed that plants should be 
exposed to the following additional environmental conditions:  
a) A continuous 28 day period at a minimum relative humidity of 75% (±5%) (whilst day and 
night time temperatures are maintained at 21°C to 25 °C); 
b) High humidity in conjunction with the above temperatures w ill encourage the expression of 
foliar symptoms of fungal infection (for example including some of the species identified in 
Part 4.3.2  of this risk management proposal) . 
                                                           
 
8 For th e purpose of this risk management proposal , a “growing season” is defined as the period during which plants are exposed to spring- summer - and 
autumn- like conditions.   
25 (101) A continuous 28 day  period with a daytime temperature range between of 25°C and 30°C, and 
night time temperatures above 20°C. Plants must continue to be held at a minimum relative 
humidity of 75% (±5%) during this time:  
a) These conditions are likely to be conducive to symptom expression and/or growth of 
regulated pests  such as Ceratocystis and Phytophthora spp.  (see part 4.3.2 ) and regulated 
bacteria including S. citri and X. fastidiosa (see Part 4.3.1 ); 
b) This regime must be applied after plants have been exposed to conditions described in 
paragraph (100) ; 
(102) The environmental conditions  described in paragraphs (100)  and (101)  can be applied at any time 
during the summer growth period, with consideration given to how plants will best acclimatise and adapt physiologically to these condi tions . 
(103) The high humidity conditions described in paragraphs (100)  and (101)  are only required in the 
first growing season. The proposed temperature regimes will be  required in both seasons.  
4.1.1.3  Autumn- like conditions for two months  
(104) Plants must be held for two months at a temperature range between 15°C and 18° C for the  
autumn- like period of each growing season although lower temperatures may be applied at night 
time.  
(105) It is considered important for plant health to expose plants to autumn- like temperatures prior to 
transitioning into dormancy to mimic the natural seasonal  cycle.  Growing season inspections will 
also be required in autumn to identify any regulated pests that may induce symptoms under these 
conditions.  
4.1.1.4  Dormancy for two months  
(106) Plants must be held dormant for two months at the end of the first growing season t o ensure that 
there is a clear separation between seasons, and to mimic the natural seasonal cycle.  
(107) During dormancy it is expected that plants will be held at temperatures that will provide  sufficient 
chilling hours for leaves and buds to develop normally in the spring of the following growing 
season. If necessary, plants can be transferred to a cool room that is part of the quarantine facility 
in order to reliably apply the required temperatures. For the types of Prunus plants for planting 
imported into New Zealand, it is understood that temperatures between 2°C and 7°C will generally achieve this purpose.  
(108) Temperatures that will be applied during dormancy must be described in the facility operating manual and approved by MPI before use.  
4.1.2 Plant health inspections  
(109) All plants must be  regularly inspected throughout the quarantine period, as described in Part 
2.3.3 of the draft standard, to detect any disease symptoms, and identify any regulated pests, as soon as possible.  
4.1.2.1  Inspections by the post entry quarantine facility operator (or nominated delegate)  
(110) The facility  operator (or a nominated delegate) must inspect all plants for signs and symptoms of 
pests and diseases two times per week for the duration of the quarantine period:  
a) As stated in the post entry quarantine facility standard, if plants are bagged and held in cool 
storage for dormancy, inspections are not required during this time;   
26 b) It is a requirement  of the post entry quarantine facility standard that accurate records must 
be kept of all inspections;  
c) The facility  standard also describes actions that must be taken following the detection of a 
pest or disease in post entry quarantine.  
(111) Information about inspections by the operator is given in part s 3.6.1 of both the MPI Facility 
Standard: Post Entry Quarantine for Plants  and the Guidance Document: Post Entry Quarantine 
for Plants . Part 3.7 of these documents includes information about reporting timeframes and 
actions to be taken by the facility operator if a disease organism is detected in post entry 
quarantine.  
4.1.2.2  Inspections by the MPI inspector  
(112) The MPI inspector  must inspect all plants in the post entry quarantine greenhouse for signs and 
symptoms of regulated pests and disease at regular intervals throughout the quarantine period.  
(113) A total of ten inspections  will be done by the inspector ( five in each growing season):  
a) During the first  growing season, inspections should be completed as follows:  
i. Inspection 1: within 14- 28 days of all plants entering a state of active growth in the 
Level 3B greenhouse;  
ii. Inspection 2: during the final 14 days of  the four month period of spring like growth in 
the first growing season;  
iii. Inspection 3: when plants are being grown between 21° C and 25°C with relative 
minimum relative humidity of 75% (±5%) ;  
iv. Inspection 4: either during the final seven days of the 28 day period at 25°C to 30° C, or 
in the seven days immediately following the completion of this period;  
v. Inspection 5: during the final 28 days of growth under autumn- like conditions.  
b) Inspections  will be done at similar times in the second growing season.  
(114) Information  about inspections by the MPI inspector is given in part 3.6.2 of the MPI Facility 
Standard: Post Entry Quarantine for Plants  and the Guidance Document: Post Entry Quarantine 
for Plants . 
4.1.3 Testing for regulated pests 
(115) All plants will require testin g to verify freedom from regulated pests as follows:  
a) Diagnostic testing:  
i. Diagnostic testing may be undertaken when disease symptoms become evident on a 
plant in post entry quarantine to verify the regulatory status of the organism causing the 
symptoms;  
ii. Depending  on the type of symptoms, samples may be tested for the presence of 
various classes of disease organism, including bacteria, fungi, oomycetes, 
phytoplasmas, viroids and viruses;  
iii. The exact diagnostic test(s) that will be done will be decided on by the MPI inspector, and by staff at the diagnostic  facility. This will depend on the type of disease 
symptom(s) that are present.  
b) Mandatory testing:   
27 i. Mandatory testing is targeted testing that must be done for specified regulated pests 
(identified in Schedules 1 and 2  of the draft standard) , regardless of whether or not the 
plant is showing signs or symptoms of pests or disease;  
ii. Mandatory  testing is required  to provide additional assurance that a consignment is free 
from particularly  high risk regulated pests, and/or if it is recognised that growing season 
inspection may not effectively manage the risk (e.g. when it is known that a particular 
regulated pest has a prolonged latent period, meaning that infected plants may not show symptoms in post entry quarantine).  
iii. Sampling times, and the type of tests requir ed are given in Schedules 1 and 2 of the 
draft standard.  
(116) All testing must be done  in a diagnostic facility accredited to the 
MPI Standard 155.04.03: A 
standard for diagnostic facilities which undertake the identification of new organisms, excluding 
animal pathogens . 
 Proposed requirements for post entry quarantine 
(117) On arrival in New Zealand, all Prunus  plants for planting will require post entry quarantine in a 
greenhouse accredited to the MPI Facility Standard: Post Entry Quarantine for Plants , as 
described in Part 2.4 of the draft standard. The purpose of this is to ensure that any regulated 
pests that are imported in association with Prunus  plants for planting do not escape into the wider 
environment whilst plants are being screened for these pests . 
a) The facility  standard sets the operational and structural requirements for post entry 
quarantine facilities;  
b) All facilities are regularly audited by MPI to ensure ongoing compliance with all relevant standards.  
(118) The quarantine period and level of post ent ry quarantine are discussed in the following sections.  
4.2.1 Quarantine period  
(119) Prunus  plants for planting will require 2 1 months post entry quarantine before they can become 
eligible for a biosecurity clearance ( this requirement may differ when plants are produc ed under 
an Export Plan or obtained from an Offshore Facility , as discussed  in Part s 3.2.1  and 5.2 of this 
risk management proposal).  
a) This is the minimum amount of time that will be needed to screen plants for regulated pests;  
b) During this time the plants will have two complete growing seasons, and one period of dormancy in between the first and second growing seasons;  
c) Factors that were considered when determining the length of the quarantine period are 
discussed below.  
(120) The quarantine period must be long enough to ensure that, when combined with other risk 
management measures, risk will be appropriately  managed before a  biosecurity clearance is 
issued.  
a) The two growing season period combined with applying defined environmental conditions 
and doing mandatory testing for specified regulated pests is intended to maximise the likelihood of detecting pests identified in the draft standard, and hence minimise biosecurity risk associated with these pests;  
b) Mandatory t esting over two growing seasons is considered necessary to manage risk from 
certain high risk p ests, as identified in Part 4.3
 of this risk management proposal;   
28 c) As well as managing known risk, post entry quarantine is an important measure by whic h 
new risk organisms or new host associations are identified on the plants for planting 
pathway. There are multiple examples of new host associations being identified in plants in post entry quarantine in New Zealand. This highlights the need for plants to be grown under 
conditions known to be broadly conducive to disease symptom expression, and for the quarantine period to be long enough to allow organisms which may be at very low concentrations, and for which specific testing is not required, to build up sufficiently to induce symptoms. Two growing seasons is considered an appropriate amount of time to 
achieve this goal.  
(121) The proposed quarantine period is shorter than the previous requirement (which was for all 
Prunus  plants to be in a state of active growt h for a minimum 24 month period). The combination 
of measures proposed in the draft standard is considered likely to manage risk at least as 
effectively as previous requirements, and is consistent with the level of protection previously 
established for hig h value plants for planting, including as part of the recent public consultation on 
risk management measures for Actinidia  plants for planting (in 2018).  
(122) MPI accept that there is a high level of uncertainty to consider when setting a post entry 
quarantine period. The proposed quarantine period of 2 1 months is intended to provide a high 
likelihood of detecting any regulated pests  that are present in imported plants for planting, while 
at the same time being a balanced approach in terms of not imposing overly  restrictive quarantine 
requirements.  
4.2.2 Level of post entry quarantine  
(123) The level of post entry quarantine is determined  by the pests of concern identified for any given 
plant genus,  and the specific containment features required to contain these pests.  
a) For Prunus  plants for planting from non- approved sources , it is proposed that plants  should 
be held in a Level 3B quarantine greenhouse for disease screening in the first growing 
season. In the second growing season, the importer may elect to transfer plants t o a Level 
3A greenhouse for the remainder of the  quarantine period. If transferred to a Level 3A 
greenhouse, this can be done at the time plants enter dormancy, after all leaves have 
dropped;  
b) For Prunus plants for planting from offshore facilities  (or obta ined under an Export Plan),  
Part 5.2, paragraph (185) , explains that if material from an approved source needs residual 
screening on arrival in New Zealand, this will likely require quarantine in a Level 3A 
greenhouse, not  a Level 3B  greenhouse.  
4.2.2.1  Level 3B post entry quarantine greenhouse  
(124) A Level 3B post entry  quarantine greenhouse is the most secure level of quarantine facility  under 
the MPI Facility Standard: Post Entry Quarantine for Plants . This level o f facility can provide 
containment of  highly mobile spore- dispersed organisms, as well as mite -vectored organisms, 
which is considered particularly important in the first growing season. This is because plants will 
be of an unknown phytosanitary status (as ide from being visually inspected by the NPPO of the 
exporting country prior to export) and will be exposed to environmental conditions in post entry 
quarantine that may be conducive to the production of dispersal structures such as windborne 
spores.  
(125) In pa rticular, t he first growing season will be used to verify freedom from the highest risk 
regulated pests  (such as Phytophthora spp., phytoplasmas, Plum pox virus  and X. fastidiosa ). 
These types of organism require containment in a Level 3B greenhouse because of their means 
of dispersal, and/or because of their  potential high impact.   
29 4.2.2.2  Level 3A post entry quarantine greenhouse  
(126) Quarantine in a Level 3A greenhouse for the second growing season  (and for the period of 
dormancy between the first and second seasons)  is considered to correspond with the level of 
residual risk associated with Prunus  plants for planting for the following reasons:  
a) Screening for highly mobile and particularly high risk regulated pests , along with mandatory  
testing  for other regulated  pests , will have been done in the first growing season, so the 
plants will no longer be of unknown phytosanitary status;  
b) Plants will have been regularly inspected for disease symptoms  over the previous ten 
months, with remedial action (e.g. treatment) tak en if any regulated pests are identified;  
c) Risk associated with water -borne regulated pests will be effectively managed in a Level 3A 
greenhouse given the requirement for all waste water to be treated before exiting the facility . 
(127) Although risk will be lower  in the second growing season, it is recognised that sporulating 
organisms (which may not be contained within a Level 3A greenhouse based solely on the 
physical requirements for this level of facility) could still be present in the imported plants. However , the following operational measures are considered sufficient to manage this risk during 
the second season:  
a) Regular plant health inspections (twice per week) must be completed by the post entry  
quarantine facility operator in order to detect any disease s ymptoms as soon as practical;  
b) Contingency plans must be developed to describe actions that will be taken to contain any  
spore- borne disease organisms within the facility in the event that disease symptoms are 
observed;  
c) Operational restrictions must be appl ied to minimise the likelihood of spores being dispersed 
outside the PEQ facility. In particular, overhead irrigation will be prohibited; this will minimise the chances of fungi which are aerially dispersed (e.g. by rain splash) from escaping from 
the faci lity. 
(128) Level 3A post entry quarantine greenhouses must be fitted with a heating and cooling system  that 
has sufficient capacity to  maintain  relevant environmental conditions throughout the growing 
season.  
(129) If a request is made to transfer plants to a Level 3A greenhouse  in the second growing season, 
this will only be allowed if:  
a) All environmental conditions were applied as required in the first growing season;  
b) All mandatory  testing was completed during the first growing  season;  
c) Remedial actions were taken to manage  the risk associated with any regulated pests that 
were detected in the first growing season, including verification that any remedial actions 
were effective.  
 Summary of regulated pests 
(130) This part of the risk management  proposal summarises regulated pests of Prunus  plants for 
planting which require specific phytosanitary measures to be applied in post entry quarantine.  
(131) Pests identified in this section are those which the MPI risk analysis concluded should be 
regarded as regulated. Information about entry, establishment and impact is included in the risk analysis, but not repeated here.  
(132) Growing season inspection throughout the quarantine period is a general requirement that must be applied to help manage risk from all regulated pests that may be associated with plants for planting imported into New Zealand. This may be considered sufficient to appropriately manage  
30 risk from some regulated pests, for example where there is evidence where disease symptoms 
will be expressed in  the post entry quarantine greenhouse,  or where pests are likely to have a 
limited impact. For other pests, where there is greater risk and/or evidence that symptoms will not be seen in quarantine, additional measures (for example specific testing using PC R) may be 
required. The combination of measures proposed to manage each regulated pest  are identified in 
this section.  
4.3.1 Bacteria  
(133) The MPI hazard identification recognised  seven  species  or pathovars  of bacteria as regulated 
pests on Prunus  plants for planting:  
a) Pseudomonas amygdali , Pseudomonas cerasi, Pseudomonas syringae pv. avii, 
Pseudomonas syringae pv.  cerasicola  and Xanthomonas prunicola . All of these  species are 
expected be detected during growing season inspection over  the proposed 21 month period 
of post entry quarantine under environmental  conditions described in Part 4.1.1 . As such, 
risk management measures  other than growing season inspection are not considered 
necessary for these species, for the following reasons : 
i. Visible symptoms of infection with P. amygdali on  Prunus  dulcis (almond) are 
expressed  in the spring following infection (which generally occurs in autumn).  
- Impor ted plants will undergo two periods of growth under spring- like conditions 
during the 21  month period of post entry quarantine;  
- No records  were found of P. amygdali  causing asymptomatic infections ; 
- No reports were  found of P. amygdali affecting any Prunus  spp. other tha n P. 
dulcis . 
ii. There is n o specific information about how long it would take for symptoms of infection 
with P. cerasi  (first identified in 2016)  to become visible . However, t his species is likely  
to display similar characteristics to other memb ers of the genus, including those 
assessed here;  
iii. Visible symptoms of infection with P. syringae pv. cerasicola  became evident between 
two weeks and 90 days after inoculation of actively growing Prunus  spp., depending on 
the host species.  
- After inoculation , plants were held at temperatures between about 20°C and 
30°C; 
- Plants will be held within this temperature range during the summer -like 
conditions  in post entry quarantine.  
iv. Visible symptoms of infection with P. syringae pv. avii became visible within months of 
experimental inoculation of plants;  
v. Visible signs of infection with X. prunicola became visible within five days after artificial 
inoculation on plants held at 30°C with a 16 hour photoperiod.  
b) Spiroplasma citri and Xylella fastidiosa. Both of these species  were identified  as requiring 
specific phytosanitary measures in post entry quarantine,  in addition to growing season 
inspection,  as discussed below.  
4.3.1.1  Spiroplasma citri  
(134) Specific phytosanitary measures in post entry quarantin e, namely testing using PCR, are justified 
and sufficient to manage the risk from S. citri on Prunus  plants for planting for the following 
reasons:   
31 a) S. citri has the potential to cause economic impacts if introduced into New Zealand9. 
i. S. citri causes stubborn disease of citrus, a high impact disease which can be a 
significant restraint on citrus production. The domestic value of the New Zealand citrus 
industry was $61 million in 2017;  
ii. S. citri also causes disease on other hosts, including purple leaf of carrot.  
b) S. citri may not be detected by visual inspection of Prunus  plants for planting.  
i. There are reports that S. citri is associated with Prunus  spp. that do not display any 
symptoms of infection.  
c) S. citri is likely to be able to establish in New Zealand.  
i. Known host plants are present in New Zealand;  
ii. The New Zealand climate is likely to be suitable for establishment;  
iii. The bacterium may be spread by the propagation of infected planting material.  
d) There is the potential for S . citri  to be transmitted t o other plant hosts if it were to arrive in 
New Zealand.  
i. S. citri is transmitted by phloem feeding leaf hoppers in the genera Circulifer, 
Scaphytopius and Neoaliturus . 
- Although these genera are not present in New Zealand, they are in the family 
Cicadellida e, subfamily Deltocephaline, which is well represented in New 
Zealand;  
- Another species in the same subfamily, Macrosteles fascifrons , is an 
experimental vector . One member of this genus  is present in New Zealand, so 
may be able to act as a vector . 
e) PCR is likely to detect S. citri in Prunus  plants for planting.  
i. Detection of S. citri by PCR is very sensitive, fast and more reliable than woody 
indexing and culturing10; 
ii. It is considered import ant to grow plants under conditions likely to be conducive to the 
disease, even when using PCR for detection, based on information that, in Citrus , S. 
citri may be unevenly distributed and present at very low levels, as described by Shi et 
al., 201411. Similarly, as identified in the risk analysis, sampling of Prunus  avium 
orchards showed that the number of trees in which S. citri could be detected varied 
between seasons and years.  
(135) The optimal  temperature range for S. citri  to multiply and produce symptoms is  between 28°C 
and 35°C (in Citrus )10. As such it is proposed that samples for PCR should be collected following 
the four week period of growth between 25°C and 30°C,  described in Part 4.1.1 . Because of 
variation observed between seasons, it is proposed that mandatory testing for S. citri  should be 
done in both growing seasons.  
                                                           
 
9 Although recorded in some international databases as being present in New Zealand, MPI has no records of S. citri occurring here. The int ernational 
records are seen as unreliable and MPI consider this pathogen to be absent from New Zealand. MPI is working to remove these r ecords from international 
databases.  
10 MPI (2016) Risk Management Proposal: Import health standard (IHS) 155.02.06: Impo rtation of Nursery Stock, schedule of special conditions for Citrus  
(including Citrus , Fortunella, and Poncirus ) from all countries. https://www.mpi.govt.nz/dmsdocument/14137 . 
11 Shi, J., Pagliaccia, D., Morgan, R., Qiao, Y., Pan, S., Vidalakis, G., & Ma, W. (2014). Novel diagnosis for citrus stubborn disease by detection of a 
Spiroplasma citri -secreted protein. Phytopathology, 104(2), 188- 195.  
32 4.3.1.2  Xylella fastidiosa  
(136) Specifi c phytosanitary  measures in post entry quarantine, namely quantitative PCR (qPCR) 
testing over two growing seasons  using samples taken from plants growing under summer -like 
conditions,  are justified and sufficient to manage the risk from X. fastidiosa on Prunus  plants for 
planting for the following reasons:  
a) X. fastidiosa has the  potential to cause economic, environmental and social impacts if 
introduced into New Zealand.  
i. X. fastidiosa  causes devastating diseases in crops which are important to the New 
Zealand economy, including grapes and citrus;  
ii. X. fastidiosa causes phony peach disease, which can be a major factor limiting peach 
production;  
iii. X. fastidiosa is known to be capable of infecting native New Zealand plant genera including iconic speci es such as pōhutukawa and kauri .  
b) X. fastidiosa  is likely  to be able to establish in New Zealand.  
i. Known host plants are present in New Zealand;  
ii. The New Zealand climate is likely to be suitable for establishment.  
c) There is the potential for X. fastidiosa  to be transmitte d to other hosts if it were to arrive in 
New Zealand.  
i. At least one known vector of X. fastidiosa is present in New Zealand. Many other insect 
species in the same family as the known vector are present in New Zealand, and are potential vectors of X. fastidiosa . 
d) X. fastidiosa  may not be detected by visual inspection  of Prunus  plants for planting.  
i. Symptoms vary between Prunus  spp. and cultivars, and may not be reliable to diagnose 
infection by X. fastidiosa ; 
ii. Asymptomatic infections frequently occur in m any hosts, often for a long time after 
inoculation.  
e) Molecular  diagnostic techniques are known to be a reliable and sensitive method for 
detecting X. fastidiosa . 
(137) It is proposed that samples  for qPCR testing should be taken following a four week period of 
growth between 25°C and 30°C to maximise the likelihood of detecting X. fastidiosa , for the 
following reasons:  
a) The optimal  temperature range for  growth of  X. fastidiosa is between 25°C and 32°C, based 
on in planta and in vitro experiments
12. Low temperatures may limit disease progression and 
higher temperatures may limit survival of X. fastidiosa12; 
b) There is evidence that the bacterium  does not move into the new season’s  growth until the 
middle of summer13. For deciduous plant species including Prunus  spp., X. fastidiosa could 
be detected in leaves collected during summer , but not in a symptomatic leaves collected 
earlier in the season.  
                                                           
 
12 Feil, H., & Purcell, A. H. (2001). Temperature -dependent growth and survival of Xylella fastidiosa in vitro and in potted grapevines. Plant Disease, 85(12), 
1230- 1234.  
13 Anon (2016). PM 3/82 (1) Inspection of places of production for Xylella fastidiosa.  Bulletin OEPP/EPPO 46(3) , 407– 418  
33 (138) There is some evidence that early infections may lead to false negative results14, and there are 
still significant knowledge gaps around the latency period of X. fastidiosa . Some observations 
from recent conferences suggest latent periods may  range from 3 -14 months depending on 
strain and host , although there is  some evidence that symptoms may develop relatively rapidly  in 
susceptibl e Prunus cultivars15. Hence, testing must be done in both growing seasons to provide a 
very high degree of certainty that plants are free from X. fastidiosa . 
4.3.2 Fungi  and oomycetes 
(139) Twenty one species of fungi  and oomycetes  were considered as regulated pest s on Prunus  
plants for planting in the MPI risk analysis.  
a) As noted in paragraph (33), only a limited number of fungi, identified using major literature 
sources, were considered as part of th e hazard identification and risk assessment.  
b) This means that some species of regulated fungi  and/or oomycete , in particular those where 
risk will be managed by the generic measures  of the draft standard (for example growing 
season inspection) may not be li sted in the standard. If such species are identified on 
Prunus  plants for planting, their regulatory status will be assessed with reference to the MPI 
BORIC  database.  
(140) The risk analysis showed that risk from some of the fungi and oomycetes considered as regulated 
pests would be appropriately  managed in post entry quarantine without any risk management 
measures  other than growing season inspection. This is because visible symptoms are expected 
to become evident over  the proposed 21 month period of post entry quarantine under 
environmental conditions described in Part  4.1.1 , based on information in the risk analysis . 
a) This applies to the following species:  
i. Apiosporina morbosa  (disease symptoms reported as developing rapidly in spring with 
no evidence symptoms will not become evident within two growing seasons);  
ii. Blumeriella jaapii (infections established in a greenhouse- controlled environment held 
at 26 (±3)°C in daytime and 20 (± 3) °C at night time with 70 –90% relative humidity);  
iii. Naganishisa usbekistanensis  (limited evidence about the pathogenicity and impacts of 
this species, with only a single record from Prunus , additional measures not justified) ; 
iv. Passalor a circumscissa  (disease development favoured by temperatures of 20°C to 
25°C and high humidity, rain and dew ); 
v. Phomopsis vexans (no specific information provided in the risk analysis regarding 
conditions required for disease development on Prunus  spp., but additional measures 
not considered justified) ; 
vi. Phytophthora palmivora (disease symptoms on cherry and apricot visible within three 
months when plants incubated between 20°C to 30° C); 
vii. Phytophthora parsiana (maximum disease inci dence on almond at 25°C to 32°C and,  
in a separate study, symptoms visible on almond within 4 months . No disease 
symptoms were observed in almond seedlings grown at 18°C to 2 5°C); 
                                                           
 
14 EFSA Panel on Plant Health (PLH). (2015). Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory, with the 
identification and evaluation of risk reduction options.  EFSA Journal , 13(1), 3989.  
15 EFSA Panel on Plant He alth (PLH), Bragard, C., Dehnen ‐Schmutz, K., Di Serio, F., Gonthier, P., Jacques, M. A., ... & Milonas, P. (2019). Update of the 
Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory.  EFSA Journal , 17(5), e05665.   
34 viii. Phytophthora tropicalis (no specific information found about conditions under which 
disease develops. S ymptoms observed on inoculated apricot seedlings within three 
months in screenhouse plants watered to field capacity ); 
ix. Podosphaera clandestina (leaf infections develop around four to six weeks after bud 
break, conidia take four to six days to develop at hi gh relative h umidity (>95%) between 
15°C to 25°C);  
x. Taphrina communis  (symptoms on leaves, shoots and fruit become evident 6- 8 weeks 
after bud break, but leaf and stem symptoms not always conspicuous. Unlikely to be a 
major pathogen so additional meas ures not considered justified);  
xi. Polystigma rubrum  (causes leaf spot leading to partial or complete defoliation, with 
some evidence of overwintering on bark. Given the weak host association with dormant 
cuttings additional meas ures not considered justified).  
4.3.2.1  Ceratocystis spp. 
(141) Specific phytosanitary  measures in post entry quarantine, namely testing using PCR, are justified 
and sufficient to manage the risk from  members of the Ceratocystis genus  on Prunus  plants for 
planting for the following reasons:  
a) C. variosp ora16, and potentially other members of the North  American clade of this genus, 
are pathogenic towards  multiple species of Prunus . In particular, C. variospora causes  
perennial cankers that  can lead to limb or tree death.   
b) Growing season inspection combined with PCR testing is likely to result in effective detection of C. variospora and related species  because:  
i. Disease symptoms  are likely to become evident in post entry quarantine:  
- Almond trees artificially inoculated with C . variospora , displayed visible 
symptoms within 18 months of inoculation
17, with canker development in almond 
being  more rapid at higher temperatures (29°C) than lower (e.g. 21° C and 
24°C)18; 
- All Prunus  plants will be exposed to environmental conditions likely to be 
conducive to expression of symptoms of infection with C. variospora  (described 
in paragraph (101) ). 
ii. Plant samples must be tested for Ceratocystis spp. by PCR using primers that will 
detect all members of the Ceratocystis genus . PCR testing must be done using stem 
samples collected at the end of the first summer growth period, and again at the end of the second summer growth period. This  increases the likelihood of detecting latent 
infections and is considered necessary given the need for MPI to have a very high degree of certainty that  members of the Ceratocystis genus are not present in imported 
plant material.  
c) The proposed measures ar e consistent with those pr eviously consulted on to manage risk 
from C. fimbriata on Actinidia plants for planting.  MPI is currently developing PCR primers 
that will detect members of the Ceratocystis genus  including those recorded as infecting 
Prunus . 
                                                           
 
16 It is noted that the existing standard records C. fimbriata as a regulated pest of Prunus . There is now good evidence that the species which infects Prunus 
is C. variospora, so the revised standard has been updated to reflect this.  
17 Teviotdale, B. L., &  Harper, D. H. (1991). Infection of pruning and small bark wounds in almond by Ceratocystis fimbriata . Plant Disease,  75(10), 1026-
1030.  
18 Moller, W. J., DeVay, J. E., & Backman, P. A. (1969). Effect of some ecological factors on Ceratocystis canker in stone fruits. Phytopathology , 59.  
35 4.3.2.2  Moni linia spp. 
(142) Five species of Monilinia  (M. fructigena , M. kusanoi , M. mumeicola , M. polystroma  and M. 
yunnanensis ) meet  the criteria to be regulated pest s for New Zealand.  
(143) Specific  phytosanitary measures in post entry quarantine, namely testing using PCR or plating 
onto suitable isolation medium are justified and sufficient to manage risk from the named 
Monilinia spp. on Prunus  plants for planting  for the following reasons:  
a) These species are perceived as presenting a significant biosecurity threat to the Ne w 
Zealand stonefruit  industry.  
i. There is some uncertainty  about potential impacts  (because it is unclear how exotic 
species would interact with M. fructicola , which  is already prese nt in New Zealand) ; 
ii. However, given the potential for high impacts  a high degree of certainty is required to 
ensure new members of this genus are not introduced into New Zealand.  
b) Monilinia  spp. are most conspicuous on infected fruit and blossoms, but other plant parts  
including leave s, twigs and branches may also be infected. Plants for planting are a kno wn 
means by which Monilinia spp. can be spread and it is known that buds may be latently 
infected . It is considered possible (although unlikely) t hat visual inspection may not manage 
all risk given that plants will not flower or fruit in post entry quarantine;  
c) Both PCR or plating onto suitable isolation medium are widely accepted as suitable 
diagnostic techniques for members of the Monilinia genus ( for example as summarised by 
the European Food Safety Authority19). 
4.3.2.3  Phaeoacremonium parasiticum and P. minimum  
(144) Specific phytosanitary  measures in post entry quarantine, namely testing using PCR or plating 
onto suitable isolation medium are justified and suf ficient to manage risk from P. parasiticum and 
P. minimum on Prunus  plants for planting  for the following reasons:  
a) These species have a broad host range and are recorded as causing disease on economically significant crops in New Zealand including apple, grapevine and kiwifruit . They  
have also commonly been reported from Prunus  plants showing severe decline symptoms ; 
b) Although there is no evidence of asymptomatic infections in Prunus , these species are 
known to be present as asymptomatic endophytes in other host species, including grapevine and kiwifruit plants;  
c) No evidence was provided about what conditions are conducive to expression of symptoms 
from these species . Exposure to the broad range of conditions proposed in part 4.1.1
 is 
considered likely to maximise the likelihood of symptom expression;  
d) PCR- based detection  or culturing on suitable isolation medium are both recognised as 
appropriate methods  to detect Phaeoacremonium spp., although PCR is likely to be more 
sensitive20,21. 
                                                           
 
19 EFSA Panel on Plant Health (PLH); Pest risk assessment of Monilinia fructicola for the EU territory and identification and ev aluation of risk management 
options. EFSA Journal 2011;9(4):2119. [155 pp.] doi:10.2903/j.efsa.201 1.2119. Available online: www.efsa.europa.eu/efsajournal  
20 Aroca, A., & Raposo, R. (2007). PCR -based strategy to detect and identify species of Phaeoacremonium  causing grapevine diseases.  Appl. Environ. 
Microbiol. , 73(9), 2911 -2918.  
21 Martín, M. T., Cobos, R., Martín, L., & López -Enríquez, L. (2012). Real -time PCR detection of Phaeomoniella chlamydospora and Phaeoacremonium 
aleophilum . Appl. Environ. Microbiol. , 78(11), 3985- 3991.   
36 4.3.2.4  Phytophthora drechsleri  and P. ramorum  
(145) Specific phytosanitary  measures in post entry quarantine, namely testing using PCR or plating 
onto suitable isolation medium are justified and sufficient to manage risk from P. drechsleri and P. 
ramorum on Prunus  plants for planting for the following reasons:  
a) These species have  a very wide host range and cause a range of symptoms including rapid 
tree death. P. ramorum is recognised by MPI as a priority disease of concern to plant health ; 
b) Given evidence suggesting that these two species may not induce visible disease symptoms 
within the proposed 21  month period of post entry quarantine, even when grown under the 
broad range of environmental conditions proposed in part 4.1.1 , relying solely on growing 
season inspection is not considered appropriate as the sole method of diagnosis ; 
c) PCR- based detection or culturing on suitable isolation medium are both recognised as 
appropriate methods to detect Phytophthora spp., for example as identified when MPI 
recently consulted on import requirements for Actinidia plants for planting.  
(146) Note that MPI is currently  conducting a research project to develop PCR primers that will 
effectively detect regulated Phytophthora species  in plant material . 
4.3.3 Phytoplasmas 
(147) Multiple  species of phytoplasma including ‘ Candidatus  Phytoplasma mali’, ‘ Ca. Phytoplasma 
pruni’ and ‘ Ca. Phytoplasma prunorum’  are regulated pests  on Prunus  plants for planting.  
(148) Specific phytosanitary measures in post entry quarantine, nam ely testing using PCR, are justified 
and sufficient to manage the risk from phytoplasmas  on Prunus  plants for planting for the 
following reasons:  
a) Phytoplasmas are known to cause serious  disease of Prunus  spp. and multiple other plant 
genera. As an example,  X-disease (caused by ‘ Ca. Phytoplasma pruni’) is one of the most 
serious diseases known in peach;  
b) Phytoplasmas may not be detected by visual inspection of Prunus  plants for planting given 
that asymptomatic infections may occur;  
c) Universal PCR primers are available to detect all known species of phytoplasma , and are 
known to be highly sensitive.  These primers are likely to detect all species of phytoplasma 
because they have been designed around highly conserved regions of the genome.  The 
primers are regularl y checked against the sequences of all isolates in the public sequence 
database by staff at the PHEL diagnostic facility, to help ensure ongoing effective detection 
of any phytoplasma that may be present in imported plants.  Phytoplasma titre is likely to b e 
higher after plants have been grown under summer -like conditions, so samples for testing 
will need to be taken towards the end of the four month period of summer -like conditions.  
4.3.4 Viruses 
(149) As noted in Chapter  8 of the import risk analysis , the hazard ident ification showed that many 
viruses listed in the existing import health standard are associated with Prunus  plants for planting  
and continue to meet the criteria to be considered regulated pest s for New Zealand . These 
species were not considered further  as part of the risk analysis . For all of these species it is 
proposed that the testing measures  in the revised standard should remain largely unchanged,  
with the exception of woody indicator testing, as  discussed in part 4.3.4.4 . 
(150) Five virus species listed in the existing standard are proposed for removal  from the revised 
standard because they are no longer considered a hazard, namely:  
a) Apricot deformatio n mosaic virus;   
37 b) Cherry line pattern and leaf curl virus;  
c) Cherry rough fruit virus;  
d) Peach yellow leaf virus ; 
e) Prunus  virus S . 
Based on information in the risk analysis, t hese species were not considered further in this risk 
management proposal , and have been removed from the draft standard . 
(151) A targeted pest risk analysis was completed for some other species of virus that are either not 
listed  in the existing standard, or that are listed in the existing standard, but where fu rther 
assessment was deemed necessary . Conclusions from targeted risk analyses  (see Chapter 8 of 
the import risk analysis)  fell into three different categories, as follows:  
a) Viruses meet the criteria to be regulated pest s; 
b) Viruses do not meet the criteria to be regulated pest s; 
c) Viruses may meet the criteria to be regulated pest s. 
(152) Viruses that fell into each of the above categories are discussed in the following paragraphs.  
4.3.4.1  Viruses that meet the criteria to be regulated pest s: 
(153) Three species of virus were considered to meet the criteria to be regulated pest s and have been 
included in the revised standard, as follows:  
a) Apricot latent ringspot virus  
i. The risk analysis concluded that growing season inspection should be considered 
sufficient to manage the risk . 
ii. It is noted that this virus is  also likely to be detected by herbaceous indexing using 
Chenopodium quinoa , which is required for other virus species . 
b) Cherry rusty mottle disease s 
i. The causal agents have not been identified, but there is evidence suggesting these 
diseases are caused by closely related viruses of the family Betaflexiviridae.   
ii. The existing standard lists  Cherry rusty mottle virus as a regulated pest, with a 
requirement for woody indicator testing. As identified in the risk analysis, the recognised 
name for this species is now Cherry rusty mottle associated virus , and this is 
understood to be one of the related Betaflexiviridae viruses responsible for causing 
Cherry rusty mottle diseases.  
iii. The risk analysis conclude d that whilst these diseases should be considered regulated 
pests, they do not meet the criteria for risk management measures other than growing 
season inspection, given the limited potential impact and the likelihood that they are 
only, or predominantly,  graft transmissible.  
iv. Based on the above information, the existing requirement for woody indicator testing has been removed. Risk from these diseases will be managed by growing season 
inspections. It is noted that PCR primers capable of detecting members of  the 
Robigovirus genus are available, which can detect Cherry rusty mottle associated virus . 
c) Prunus  necrotic ringspot virus  (almond calico and cherry rugose mosaic strains ) 
i. The risk analysis concluded that the almond calico and cherry rugose mosaic strains  of 
Prunus  necrotic ringspot virus  are not present in New Zealand and meet the criteria to 
be regulated.  Strains not present in New Zealand are currently listed as regulated in 
BORIC
.   
38 ii. The risk analysis noted that there is a high degree of uncertainty in regards to what 
strains of this vi rus are present in New Zealand, but that, based on pathogenicity 
evidence only mild strains are present, and not the two severe strains identified above.  
iii. Based on existing knowledge, it is not possible to distinguish between severe and mild 
strains using m olecular techniques . It is known that there may be asymptomatic  
infections from Prunus  necrotic ringspot virus . 
iv. Based on the above,  given that the two named strains can induce severe symptoms , 
and taking into account that PCR testing cannot  distinguish be tween strains, it is 
proposed that these strains should continue to be regarded as regulated (because they 
would likely cause increased impacts to the Prunus  growing industry ), with risk 
managed using growing season inspection.  If sever e symptoms were seen on plants in 
post entry quarantine and attributed to Prunus necrotic ringspot virus , a decision would 
be made at the time in regards to the identity of the strain.  
4.3.4.2  Viruses that do not meet the criteria to be regulated pest s 
(154) Fifteen species of virus did not meet  the criteria to be regulated pest s. These species were not 
considered further in this risk management proposal , and are not listed in the standard.  
a) Apple stem pitting virus ; 
b) Apricot vein clearing -associated virus ; 
c) Asian prunus  viruses  1, 2 and 3 ; 
d) Nectarine marafivirus M ; 
e) Peach- associated luteovirus ; 
f) Peach chlorotic leaf spot virus ; 
g) Peach chlorotic mottle virus ; 
h) Peach leaf pitting- associated virus;  
i) Peach marafivirus D ; 
j) Peach virus T ; 
k) Prunus  virus F ; 
l) Prunus  virus T ; 
m) Tobacco necrosis virus;  
n) Tobacco ringspot virus .  
Some of the viruses listed above are recently described and there is very little information about 
potential impacts they may have on Prunus  plants for planting. As such, for some species, there 
was a high degree of  uncertainty in the risk analysis conclusion. These species have not been 
considered further in this risk management proposal, or added to the revised standard. However, if new information becomes available indicating that they may have an impact, their status as regulated pest s will be reconsidered.  
4.3.4.3  Viruses that may meet the requirements to be regulated pest s 
(155) The risk analysis concluded that four  additional species of virus may meet the criteria to be 
considered regulated pest s but that there was significant uncertainty in the conclusions . Risk 
management measures for these species  were considered further in this risk management 
proposal ; proposed risk management  requirements are identified below:   
39 a) Apricot pseudo- chlorotic leaf spot virus . It is proposed that Apricot pseudo- chlorotic leaf spot 
virus  should not be regarded as a regulated pest of Prunus , for the following reasons : 
i. The potential impact of the virus remains unknown.  
- The virus has only been found in mixed infections, especially with  Apple chlorotic 
leaf spot virus, which is  present in New Zealand. This means that it is difficult to 
distinguish the symptoms of  Apricot pseudo- chlorotic leaf spot virus , and it is not 
known what economic impact the virus is likely to have.  Apricot ps eudo- chlorotic 
leaf spot virus has a wide global distribution and has been reported from multiple 
countries since 2005, wit hout evidence of severe impacts;  
- It is noted that the virus is considered unlikely to be detected during growing 
season inspections in post entry quarantine.  If introduced, it is considered to 
have the potential to establish in New Zealand.  
ii. Apricot pseudo- chlorotic leaf spot virus  is unlikely to spread widely if introduced to New 
Zealand.  
- The virus is graft transmissible and mechanical ly transmissible in some 
herbaceous plants . There is no information on other transmissions routes, such 
as insect vectors ; 
- This means that  the virus is unlikely to spread beyond cultivars in which it is 
originally introduced.  
iii. Impacts of the disease would not be felt beyond the stonefruit industry  
- Apricot pseudo- chlorotic leaf spot virus  has only been recorded from Prunus  
species.  
b) Cherry  associated luteovirus . Given the recent identification of Cherry  associated luteovirus , 
and because it has only been recor ded from two countries, a precautionary approach is 
being applied until more information becomes available.  It is proposed that Cherry  
associated luteovirus  is regarded as a regulated pest, with a requirement for growing 
season inspection in post entry quarantine, for the following reasons : 
i. Cherry  associated luteovirus  is a newly described virus, first recorded in 2017.  
- There remains  uncertainty about symptoms and potential impacts from this virus , 
given that it has been found in mixed infection with other important plant viruses ; 
ii. Cherry  associated luteovirus  is considered likely to spread within the stonefruit industry  
if it establishes in New Zealand.  
- The virus is aphid transmitted, and luteovirus transmitting aphids , including green 
peach aphid,  are pr esent in New Zealand and reported from stonefruit;  
- Cherry  associated luteovirus  has only been recorded from Prunus  species, so 
impacts of the disease are unlikely to be felt beyond the stonefruit industry.  
iii. The risk analysis concluded that, if considered a regulated pest, Cherry  associated 
luteovirus  does not meet the criteria for risk management measures other than growing 
season inspection.  
c) Nectarine stem pitting associated virus . It is proposed that Nectarine stem pitting associated 
virus is regarded as a regulated pest, with a requirement for growing season inspection in 
post entry quarantine, for the following reasons : 
i. Nectarine stem pitting associated virus  is a recently identified virus, first detected in 
symptomatic plants in 2015.   
40 - There remains uncer tainty about specific symptoms. The virus has been 
detected in plants displaying various symptoms, although this has been in plants 
in which other viruses were also detected;  
- Given the recent identification of Nectarine stem pitting associated virus , and 
because it has a reasonably limited distribution (only recorded from five 
countries), a precautionary approach is being applied until more information becomes available.  
ii. Nectarine stem pitting associated virus  is considered likely to spread within the 
stone fruit industry if it establishes in New Zealand.  
- The virus is a luteovirus, and these are known to be aphid transmitted. Luteovirus transmitting aphids, including green peach aphid, are present in New Zealan d 
and reported from stonefruit;  
- Nectarine stem pi tting associated virus  has only been recorded from Prunus  
species, so impacts of the disease are unlikely to be felt beyond the stonefruit industry.  
iii. Measures beyond growing season inspection are not proposed based on current 
evidence.  
- It is noted that ther e are some reports of asymptomatic infections of Nectarine 
stem pitting associated virus , meaning that it is possible this virus may not be 
detected in infected plants in post entry quarantine;  
- As described in Part 2.3 of this risk management proposal, the required strength 
of a measure depends on the risk posed by a particular regulated pest on a particular pathway and is determined by a combination of t he consequences the 
pest may cause if it was introduced into New Zealand and the likelihood that the 
pest will enter and establish from a pathway . In this case, given the uncertain 
impacts of Nectarine stem pitting associated virus , additional measures in post 
entry quarantine are not considered justified at present . 
4.3.4.4  Testing measures for viruses  
(156) A combination of some, or all, of the following measures are proposed to manage risk associated 
with regulated viruses listed in the standard:  
a) Growing season inspec tion for signs and symptoms of virus infection;  
b) Mandatory  testing by PCR using leaf samples collected after plants have been grown in 
spring- like conditions for at least two months (see part 4.1.1
 for the proposed conditions ); 
i. For Plum pox virus , it is proposed that two sets of PCR testing should be done (using 
samples collected in spring in both the first and the second growing season) . 
c) Herbaceous indexing using  a combination of the following indicator species:  
i. Chenopodium quinoa , Cucumis sativus, Nicotiana occidentalis and Nicotiana 
benthamiana;  
ii. Viruses for which h erbaceous indexing is required are  identified in Table 1;  
(157) The measures  described above are considered justified, and appropriate,  for the following 
reasons:  
a) Plant viruses have commonly been identified in plants in post entr y quarantine in New 
Zealand during growing season inspections . However because some viruses can cause  
41 latent infections22, growing season inspection will not manage risk  from all regulated virus 
species  to an appropriate level ; 
b) PCR is highly specific and sensitive and is known to be an effective method to detect plant 
viruses that are systemically distributed throughout infected plants , including latent 
infections, provided that primers adequately capture sequence variability amongst different strains ; 
i. Two sets of PCR testing are proposed when testing for Plum pox virus , one in each 
growing season. This reflects the potential high impact of the disease, and the fact that 
detection may not be reliable in shoots that are less than one year old
23. 
c) Herbaceous indexing will provide additional assurance that plants are free from  variant 
strains of mechanically  transmissible viruses that may not be detected using PCR;  
i. Herbaceous indicator species identified in Table 1 are based on information in the 
existing standard and in the MPI Prunus  (Stonefruit) Post -Entry Quarantine Testing 
Manual;  
ii. Herbaceous indexing may also detect new or emerging mechanically  transmissible 
viruses for which  reliable  PCR assays are not yet available.  
(158) The existing standard gives the option for ELISA testing to be used as an alternative to PCR. 
ELISA has not been retained as a testing option because it is generally less sensitive than PCR.  
a) MPI recognise that ELISA may be a highly specific and sensitive method to detect some virus species. As such, where quantitative data is available that gives evidence of sensitivity 
and specificity equivalent to PCR , we would consider a request f or ELISA to be considered 
equivalent to PCR.  
(159) MPI is propos ing removing the option of woody indicator testing as a method to detect viruses  on 
Prunus plants for planting. This is because it is now widely seen as being of limited benefit (for 
example as summarised by Legrand, 2015
24). 
a) The method can provide false negative and inconsistent results. This means that the 
absence of symptoms in indicator plants does not necessarily prove that imported plants are free from the target regulated pests ; 
b) Even when w oody indicator testing returns a positive result, it is recommended that the 
result is verified using another type of test (e.g. PCR).  
(160) Despite its limitations, woody indicator testing continues to be an internationally recognised 
technique for dealing with diseases of unknown aetiology, and MPI acknowledge that it may still 
have the potential to identify new or emerging virus species, or variants of existing species that may not be detected by PCR or herbaceous indexing. However, given the drawbacks identif ied 
above, and the need to verify test results using other test methods, we no longer consider this method appropriate for use as a mandatory test for viruses on imported Prunus plants for 
planting.  
(161) In some  cases in the existing standard, woody indicator t esting was included as an optional test , 
with the alternative being herbaceous indexing. In these  cases, the option for woody indicator 
testing has been replaced with a mandatory requirement for herbaceous indexing. This applies to 
the following species of  virus:  
                                                           
 
22 Maliogka, V., Minafra, A., Saldarelli, P., Ruiz -García, A., Glasa, M., Kati s, N., & Olmos, A. (2018). Recent advances on detection and characterization of 
fruit tree viruses using high- throughput sequencing technologies. Viruses, 10(8), 436.  
23 IPPC (2018). ISPM 27 Diagnostic protocols for regulated pests  DP 2: Plum pox virus.  
24 Legrand, P. (2015). Biological assays for plant viruses and other graft ‐transmissible pathogens diagnoses: a review. EPPO Bulletin, 45(2), 240- 251.  
42 a) Apricot latent virus ; 
b) Carnation Italian ringspot virus ; 
c) Cherry Hungarian rasp leaf virus . 
(162) In some cases where woody indicator testing was previously required, PCR tests are now 
available, or there is sequence information that will allow such tests to be developed. This applies 
to the following species of virus,  for which PCR testing has been added as a requirement :  
a) Cherry rasp leaf virus ; 
b) Cherry twisted leaf associated virus ; 
c) Little cherry virus -2; 
d) Raspberry ringspot virus ; 
e) Stocky prune virus . 
(163) In cases  where woody indicator testing is a mandatory requirement under the existing standard, 
but other test methods are also required (herbaceous indexing and/ or PCR) , the requirement for 
woody indicator testing has been removed, but not replaced with any other testing method.  This 
applies to the following species of virus:   
a) Cherry leaf roll virus  strains not in New Zealand (also has PCR and herbaceous indexing) ; 
b) Cherry mottle leaf virus  (also has PCR and herbaceous indexing) ; 
c) Myrobalan latent ringspot virus  (also has herbaceous indexing);  
d) Peach enation virus  (also has herbaceous indexing);  
e) Peach mosaic virus  (also has herbaceous indexing);  
f) Peach rosette mosaic virus  (also has PCR and herbaceous indexing);  
g) Plum pox virus  (also has two sets of PCR and herbaceous indexing);  
h) Tomato ringspot virus  (also has PCR and herbaceous indexing).  
4.3.4.5  High throughput sequencing as a phytosanitary measure  
(164) MPI has evaluated whether to include a mandatory requirement for testing using high throughput sequencing, either as an additi onal test method to assess the viral phytosanitary status of 
imported material, or as a replacement for herbaceous indexing. The decision was made to retain herbaceous indexing as a test method and not to include high throughput sequencing at present , 
for the following reasons:  
a) Despite known limitations of biological indexing
24, herbaceous indexing remains an 
internationally accepted tool for diagnosing mechanically transmissible plant pathogens 
including certain virus species. It is known to be capable of detecting strains that may not be 
identified by PCR, and/or new and emerging organisms for which molecular data is not 
available;  
b) There are still multiple limitations that need to be resolved before high throughput sequencing can be accepted as a routine test method (for example, as summarised in 
Maliogka et al., 2018
25). In particular, there are still no agreed international standards on 
what is con sidered an acceptable coverage of a virus genome to be considered a reliable 
                                                           
 
25 Maliogka, V., Minafra, A., Saldarelli, P., Ruiz -García, A., Glasa, M., Katis, N., & Olmos, A. (2018). Recent advances on detection and characterization of 
fruit tree viruses using high- throughput sequencing technologies. Viruses, 10(8), 436.   
43 positive, the acceptable number of reads for data to be considered reliable, or the depth of 
coverage that is required across the genome to be considered a reliable positive;  
c) High throughput sequencing is not yet accepted as a routine quarantine diagnostic 
technique by the majority of NPPOs, including those NPPOs with similar biosecurity 
approaches to New Zealand;  
d) MPI is actively evaluating the potential for using high throughput s equencing as a routine 
diagnostic method, including working in collaboration with international trading partners. This 
is because there will be numerous advantages to using this technique, including potential 
greater sensitivity than biological indexing, and more rapid testing. Staff at the MPI PHEL 
diagnostic facility (the only accredited diagnostic facility with current capability to do mandatory testing for Prunus  plants for planting) do not yet have sufficient data, or a 
finalised standard operating procedure for using high throughput sequencing as a technique 
for mandatory testing. It is not considered appropriate to include high throughput sequencing 
as an approved diagnostic technique before it has been fully validat ed and procedures are 
finalised;  
e) As soon as there is sufficient data and established procedures, MPI will update the import 
health standard and consult on proposed changes to testing requirements.  We do not think 
it appropriate to give the option for this type of testing in the standard bef ore this information 
is available. In the meantime, if there is  data showing that high throughput sequencing 
(either alone or in combination with other techniques) would achieve the same outcome as 
the proposed testing measures for viruses (described in paragraph (156) ), MPI would 
consider any requests for equivalence in accordance with ISPM 24. Guidelines for the 
determination and recognition of equivalence of phytosanitary measures . 
 
Table 1: Summary of regulated virus species listed in the revised import health standard and the 
required disease screening measures.  
Virus species  
Growing 
season 
inspection  Herbaceous indexing (indicator 
species)1 PCR 
American plum line pattern virus    (Cq, Cs, No)   
Apple stem grooving virus  [Prunus -
infecting strain]    (Cq)  
Apricot latent virus    (No)  
Apricot latent ringspot virus     
Carnation Italian ringspot virus    (Cq)  
Cherry -associated luteovirus     
Cherry Hungarian rasp leaf virus    (Cs)  
Cherry leaf roll virus [strains not in New 
Zealand]2    (Cq, Cs, Nb)   
Cherry mottle leaf virus    (Cq)  
Cherry rasp leaf virus    (Cq, Cs, Nb)   
Cherry rusty mottle associated virus  
(and related Betaflexiviridae  viruses)     
Cherry twisted leaf associated virus    (No)  
Little cherry virus -2     
44 Myrobalan latent ringspot virus    (Cq, Cs, Nb)   
Nectarine stem pitting -associated virus     
Peach enation virus    (Cq)  
Peach mosaic virus     (Cq)  
Peach rosette mosaic virus    (Cq, Cs, Nb)   
Petunia asteroid mosaic virus     
Plum bark necrosis stem pitting -
associated virus      
Plum pox virus    (Nb)  (two 
sets)  
Prunus  necrotic ringspot virus (almond 
calico and cherry rugose mosaic strains)     
Raspberry ringspot virus2   (Cq, Cs, Nb)   
Sowbane mosaic virus    (Cq)  
Stocky prune virus     
Tomato bushy stunt virus    (Cq, Cs, Nb)   
Tomato ringspot virus    (Cq, Cs, Nb)   
Footnotes  to table : 
1 Herbaceous indicator species are as follows:  
Cq – Chenopodium quinoa  
Cs – Cucumis sativus   
Nb – Nicotiana benthamiana 
No – Nicotiana occidentalis  
At least two plants of each herbaceous indicator species must be used in each test. Tests must 
be carried out using the new season’s growth from imported plants growing under spring- like 
conditions. Plants must be sampled from at least two positions on every plant including a young, 
fully expanded leaf at the top of each plant and an older leaf from a midway position. Herbaceous 
indicator plants must be grown between 18- 25°C and must be kept in darkness  for 16-24 hrs 
prior to inoculation. Post -inoculated indicator species must be held in a glasshouse at 18- 25°C for 
at least 4 weeks and inspected at least twice per week for symptoms of virus infection.  
2 Cherry rosette virus/Cherry rosette disease associated virus is listed in the existing import 
health standard with a requirement for woody indicator testing. This has not been included in the revised standard, based on information that this disease is reported to be a complex of Raspberry  
ringspot virus and Cherry leaf roll virus . Both of these viruses are re gulated on Prunus  plants for 
planting, with a requirement for  mandatory  testing using herbaceous indexing and PCR .  
4.3.5 Viroids 
(165) Two species of viroid are recognised as regulated pests on Prunus  plants for planting, namely 
Apple scar skin viroid and Hop stunt viroid (strains not present in New Zealand) . 
(166) Specific phytosanitary measures in post entry quarantine, namely testing using PCR are justified and sufficient to manage the risk from both species of viroid, for the following reasons:   
45 a) Both species of viroid have the potential to cause economic impacts on Malus  (apple) and or 
Prunus  spp. if introduced into New Zealand.  
b) Relying on growing season inspection for detection may not effectively manage the risk  
because:  
i. There is evidence that Apple scar skin  viroid  may remain latent and symptomless for up 
to five years ; 
ii. Some cultivars of Prunus  are tolerant to Hop stunt viroid, and it is not clear if symptoms 
would be displayed in post entry quarantine.  
c) Specific testing by PCR using leaf samples (including petioles and/or mid- veins) collected 
after plants have been grown in summer- like conditions for at least two months (see part 
4.1.1 ) is expected to reliably detect both species of viroid,  given that they are know n to 
cause systemic infect ion. 
4.3.6 Diseases of unknown aetiology  
(167) The MPI import risk analysis evaluated all 64 dise ases of unknown aetiology that are listed in the 
existing Prunus  standard. Of these, eight  still meet the criteria to be considered as regulated 
pests on Prunus  plants for planting , namely:  
a) Amasya  cherry disease (formerly listed as Amasya cherry disease agent ; suspected to be of 
fungal origin) ;  
b) Cherry chlorotic rusty spot disease (formerly listed as Cherry chlorotic rusty spot agent ; 
suspected to be of fungal origin) ; 
c) Cherry necrotic crook agent ; 
d) Cherry short stem agent ; 
e) Cherry spur cherry agent ; 
f) Peach red marbling agent ; 
g) Peach stubby twig agent ; 
h) Sour cherry pink fruit agent . 
(168) Information about the eight diseases listed above is included in the MPI risk analysis. Some 
diseases of unknown aetiology not listed in t he existing standard were al so evaluated in the risk 
analysis. None of these met the criteria to be considered regulated pest s. 
(169) Previously, to manage risk from diseases of unknown aetiology, MPI has required a combination of growing season inspection and woody indicator testing using various Prunus  cultivars. Similar 
test methods have been (and continue to be) used at offshore testing facilities. This remains the 
internationally accepted method for detecting these diseases , however s ome New Zealand 
industry members have indicated a des ire to remove woody indexing as a testing requirement.  
(170) There is uncertainty around how effective woody indicator testing is to detect all of these 
diseases. This is because for six of the diseases, it is not known what symptoms will develop on indicator species listed in the existing standard. For the other two diseases, there is evidence that 
symptoms develop on Prunus  avium ‘Bing’ (this applies to Cherry short stem agent and Cherry 
spur cherry agent).  
(171) Diseases of unknown aetiology have some specific characteristics that may allow a different risk 
management approach than used in the existing standard, as discussed in the following 
paragraphs. Based on these characteristics, MPI is  proposing to remove woody indicator  testing  
as a mandatory requirement of the standard and to rely on growing season inspections to 
manage risk. MPI is particularly interested in stakeholder submissions on th is proposal .   
46 4.3.6.1  Risk management options for diseases of unknown aetiology of Prunus  
(172) There is o ften limited epidemiological information about diseases of unknown aetiology, however 
these are generally considered to have the following characteristics:  
a) Only mechanically or graft transmissible;  
b) Unlikely to cause impacts beyond the affected industries w hich directly benefit from the 
importation of new germplasm  (i.e. in this case, have a host range that is restricted to 
members of the Prunus  genus) , and unlikely to spread beyond the cultivars in which they 
are imported;  
c) Significant uncertainty around biology, including mode of transmission (i.e. given that the 
causal agent and/or vector has not been identified) and their potential impact under New 
Zealand conditions ; 
d) A high likelihood of establishment if present in plants for planting imported into New Zealand, including in commercial orchards and foundation material;  
e) Potential time -lag before infection or impacts become evident;  
f) Unable to be detected using molecular techniques, given that no nucleic acid sequence information is available.  
(173) Taking into cons ideration the above characteristics, MPI has identified three options that could be 
considered to manage risk from these diseases, as discussed below:  
a) Growing season inspection in post entry quarantine (the method proposed by MPI for 
inclusion in the draft  standard)  
i. Given the restricted host range and the limited potential for these diseases to spread 
other than by mechanical or graft transmission (based on current information), MPI is 
proposing to apply fewer interventions than in the existing standard to manage risk fro m 
diseases of unknown aetiology;  
ii. Under this approach risk management by MPI will be restricted to growing season 
inspection whilst plants are in post entry quarantine;  
iii. Because it is known that many cultivars may not display symptoms, applying growing season inspection as the sole risk management tool may not manage all risk associated 
with the introduction of these diseases. However, symptoms are more likely to be 
displayed on susceptible cultivars, which is where the diseases would have the most impact. Furthermore, if the disease is only graft transmissible, it is unlikely to spread 
beyond the cultivar in which it is originally introduced;  
iv. Under this option,  the eight  diseases of unknown aetiology  identified above  would 
continue to be regarded as regulated pests. This means that, if detected in the wider environment, MPI would need to consider whether it was necessary to initiate a biosecurity response to manage risks associated with the detection. This could have impacts on orchards or nurseries that had been exposed to potentially infected plants, 
especially if there had been large scale multiplication and distribution of imported 
material  before symptoms became evident;  
v. With regards to this option, it is noted that two of the diseases of unknown aetiology 
(Amasya  cherry disease and Cherry chlorotic rusty spot disease) are suspected to be of 
fungal origin. If this is the case, these  diseases  may be able to spread by means other 
than grafting.  
b) Risk management by industry   
47 i. MPI could consider de- regulating all diseases of unknown aetiology and relying on 
industry to mi tigate the risk as they see fit;  
ii. Because there is still considerable uncertainty around the biology and aetiology of many 
of these diseases, including uncertainty regarding modes of transmission (i.e. given that 
the causal agent and/or vector has not been identified), it is possible that a disease 
could spread more widely than expected before it was detected. This could limit the effectiveness of pos t-border management by industry;  
iii. The reason this approach could be considered for diseases of unknown aetiology of 
Prunus  is because spread of diseases that are only graft transmittable is likely to be 
able to be easily managed through the removal of any contami nated lines , and because 
any impacts are only likely to be on the Prunus  industry . It is also noted that, for this 
type of disease, any infected material imported for research and development (e.g. breeding programmes) is less likely to result in significa nt impacts, as disease impacts 
would be resolved before any material is made available for commercial distribution;  
c) Retaining the existing requirement  of growing season inspection and woody indicator testing  
i. This option may provide greater certainty that i mported plants are free from diseases of 
unknown aetiology . This is because  indicator cultivars that may be more susceptible to 
such diseases would be tested before plants are released from quarantine.  This 
approach would be consistent with the current int ernationally recognised approach, and 
with requirements of the existing standard;  
ii. If testing is not done prior to export, it would need to be done on arrival in New Zealand. 
This would rely on the New Zealand diagnostic facility having the resources and 
expertise to do such testing;  
iii. Woody  indicator testing continues to be an internationally recognised approach for 
dealing with diseases of unknown aetiology  of Prunus , despite known limitations with 
this approach, including the following:  
- Even if disease sy mptoms are observed on woody indicators, if the organism 
causing the disease symptoms is unknown (which is the case for all diseases of 
unknown aetiology), there is no practical way to confirm exactly which disease of 
unknown aetiology is present or to val idate the result with a different type of test. 
This may make it difficult to make regulatory decisions, especially if there are no signs of adverse effects on the originally imported plants  (as opposed to the 
indicator species) ; 
- For six of the eight diseases of unknown aetiology listed above, it is not known 
what indicator species should be used for disease detection, or what symptoms would be expressed. This means that while it may be more likely that symptoms 
of infection are observed on woody indicator species, there is no guarantee that this will be the case. For the other diseases , it is known that symptoms may be 
displayed on P. avium ‘Bing’. 
d) Despite known limitations, woody indicator testing remains the only method currently 
available for trying to detect diseases of unknown aetiology  (unlike  when testing for viruses, 
where multiple other test methods are usually available) . This is why woody indicator testing 
is still used internationally as a diagnostic tool . Using  this approach may increase the 
likelihood of detecting any diseases of unknown aetiology  that are present in imported 
plants, especially in cases where there is information indicating that a particular disease of unknown aetiology is likely to induce symptoms on a known indicator species.   
(174) If this proposal is adopted, it is proposed that the same indicators as required under the existing 
standard should be used  for all Prunus  spp. imported into New Zealand , as shown  in the following  
48 table. Inoculated woody indicator plants would need to be inspected for symptoms of infection for 
at least nine months : 
 
Required w oody 
indicator  species  Genus of imported Prunus  plants for planting 
Prunus  
armeniaca  Prunus  avium & 
Prunus   cerasus  Prunus  domestica & 
Prunus  salicina   Prunus  
dulcis  All other 
Prunus  spp. 
Prunus  armeniaca  
‘Tilton ’ x3    x3 
Prunus  avium ‘Bing’  x3    
Prunus  avium ‘Sam’  x3   x3 
Prunus  domestica   
‘Shiroplum ’  x3 x3  x3 
Prunus  persica ‘Elberta ’ 
or ‘GF305’  x4 x4 x4 x4 x4 
Total indicators  10 13 7 4 13 
 
   
49 5. Feasibility and practicality of proposed requirements  
(175) A key new risk management  measure that is proposed in the draft standard is the application of 
environmental conditions that will be conducive to the expression of disease symptoms. In 
particular , this includes exposing plants to high humidity  under  defined temperature regimes in 
the summer -like period of the first growing season.  MPI recognise that there may be barriers to 
implementing all proposed environmental requirements  at existing post entry quarantine facilities 
in New Zealand. This is why, under this option, a three year lead in time has been proposed in terms of applying a high humidity environment. This is intended to allow facilities to make any modifications requi red to apply such conditions.  More information about the feasibility and 
practicality of this measure is provided in Part 3.2.2.1.2
 of this risk manag ement proposal.  
(176) An alternative risk management option is to do additional PCR testing targeted at detecting 
specific high risk regulated pests , as described in Part 3.2.2.1.3 . As noted in that  Part, it may take 
some time to develop all necessary PCR tests and there would need to be a staged implementation under this approach, with new tests added as they become available.  
(177) Plants will remain in post entry quarantine for a minimum of 21  months before they  can become 
eligible for a biosecurity clearance.  
a) As noted above, as with other commodities, Prunus plants for planting can be multiplied 
during the post  entry quarantine per iod. This may be done either in the Level 3B 
greenhouse (if sufficient space is available),  in a Level 3A greenhouse in the second 
growing season, or by multiplying tissue cultures in a Level 3 tissue culture facility.  This 
means that large numbers of plan ts, especially tissue cultures, could be available for release 
by the time  a biosecurity clearance is issued  if desired . In the case of Prunus plants for 
planting, MPI recognise that propagation by tissue culture may not be desirable given the 
potential for genetic drift ; 
b) When plants are obtained  from an Offshore Facility , or in accordance with an Export Plan, 
there may be fewer post entry quarantine requirements on arrival in New Zealand. This 
means that the quarantine period may be shorter, as described in  Part 3.2.1 . 
 Import permit  
(178) As described in Part 1.6 of the draft standard, an import permit will identify:  
a) The regulated pests for which screening is required in New Zealand;  
b) The minimum quarantine period  (based on the regulated pests for which screening is 
required in New Zealand) ; 
c) The level of post entry quarantine greenhouse in which consignments must be held (based 
the regulated pests for which screening is required in New Zealand) . 
(179) Listing these requirements on the import permit is considered the best way to clearly identify  the 
phytosanitary  measures that will be required for each consignment of Prunus  plants for planting  
after they arrive in New Zealand. This is because when plants are produced under an Export Plan 
or are obtained from  an Offshore Facility , some phytosanitary measures will have been applied 
prior to export.  However, the exact measures which are applied will differ between facilities.  
(180) If plants are not obtained from an MPI-approved source, the import permit will indicate  that all 
phytosanitary measures described in the draft standard  must be applied after plants arrive in New 
Zealand, namely that: 
a) Plants must undergo all screening described in Part 2.3 of the draft standard on arrival in 
New Zealand before they can become eligible for a biosecurity clearance;   
50 b) The minimum quarantine period will be 21  months , although this may be extended if 
regulated pests are detected;  
c) Plants must be deflasked and held in  a Level 3B greenhouse for the first growing season;  
d) Plants  may be transferred to a Level 3A greenhouse for the second growing season 
provided that all mandatory  testing has been completed with negative test results returned 
and plants were  effectively treated for any regulated pests that were detected during the first 
growing season (as described in Part 4.2.2.2 ); 
e) The post entry quarantine facility(s) in which the plants must be held will be identified on the 
import permit.  
(181) If plants are obtained under an Export Plan, or from an Offshore Facility , some of the required 
phytosanitary measures will have been applied prior to import. In this case, the import permit will 
identify the residual requirements that must be applied in New Zealand, including:  
a) The requirements of Part 2.3 of the draft standard that must applied in New Zealand;  
b) The m inimum quarantine period;  
c) The level of post entry quarantine greenhouse;  
d) In this case, the length of the quarantine period and type of post entry quarantine 
greenhouse will depend on the specific regulated pests for which phytosanitary measures 
have been applied prior to export . This will be different for each Export Plan or Offshore 
Facility  (see following section) . 
(182) The outcome of including the above details on the import permit will be that for all Prunus  plants 
for planting, regardless of source, all phytosanitary measures described in the  draft standard will 
be applied before plants become eligible for clearance.  
(183) As will be stated on the permit application form, when any permit assessment begins it is 
unknown if or when a permit will be issued. This is because until an assessment is started MPI 
does not know what, if any, circumstances exist that would delay or prevent issuance of a permit. The MPI assessment will include checking the emerging risk register to ensure that any newly 
identified or emerging  risks can be appropriately managed.  
 Plants from an MPI -accredited offshore facility or produced under 
an Export Plan 
(184) The previous import health standard for Prunus  plants for planting required  plants from an 
accredited offshore  facilit y to be held in a Level 2 post entry quarantine greenhouse with  a 
minimum quarantine period of 9 months. In contrast the draft standard does not specify the level 
of quarantine facility, or the duration of the quarantine period, for plants obtained from an accredited f acility.  
a) Quarantine requirements for plants from accredited sources  are not identified in the draft 
standard because the amount of residual risk is likely to  differ between facilities . This means  
that plants from different facilities may have different quarantine requirements  on arrival in 
New Zealand. The requirements  will depend on  multiple  factors including the level of 
containment that is provided at each offshore facility, the specific tests that are done prior to export , and the residual phytosanitary  actions that need to be applied in New Zealand in 
order to meet the requirements of the new standard
26; 
                                                           
 
26 A more detailed discussion about factors considered when establishing the level of quarantine is provided in the M PI Risk Management Proposal for the 
Revision of the Facility Standard: Post Entry Quarantine for Plants .  
51 b) Once  the draft standard is issued the MPI Chief Technical Officer (CTO) will make a risk -
based decision about the post entry quarantine requirements for plants from any accredited 
source . As described in Part 5.1 , this will be identified on the import permit for each 
consignment. MPI will also update online information about  each offshore quarantine facility  
to ensure that this information is readily available.  
(185) Based on the phytosanitary measures applied at offshore facilities accredited to  export Prunus  to 
New Zealand, and the proposed requirements in the dr aft standard, it is anticipated that 
containment in a Level 3A quarantine greenhouse will be the minimum requirement  for this type 
of material . This is based on the following:  
a) Offshore facilities do not generally provide an equivalent level of risk managem ent to that 
required in the draft import health standard for bacterial,  fungal and oomycete regulated 
pests . This means that  risk management measures for these types  of organism will need to 
be applied in a temperature controlled  quarantine facility  after plants arrive in New Zealand.  
i. Most offshore facilities do visual inspections for fungi and oomycetes and apply 
fungicide if these organisms are present , or routinely as part of a regular disease 
control programme. This may supress symptoms, but will not necessarily eradicate the 
disease- causing organism ; 
ii. If specific screening  for fungi , oomycetes  or bacteria is required in New Zealand, this 
will need to be done in a facility with  appropriate structural and operational procedures 
to appropriately manage residual risk from these organisms , and with the ability to  apply 
the required environmental  conditions . As a minimum this is expected to be a Level 3A 
facility.  
b) Facilities that hold Prunus  plants for planting imported into New Zealand have historically 
been located in commercial production areas. This means that disease vectors  are more 
likely to  be present in the locality, and that there is a greater likelihood of regulated pests 
finding a suitable host in the wider environment if there is a breakdown in containment. As 
such MPI now considers that , as a minimum, plants  which need residual screening  on 
arrival in New Zealand are likely to require quarantine in  a Level 3 A greenhouse.  
 Biosecurity clearance 
(186) Meeting the requirements of the standard is necessary  before  imported plants for planting can be 
considered for biosecurity clearance. However, meeting all requirements  does not automatically 
guarantee biosecurity clearance. There are other restrictions on the giving of biosecurity 
clearance, as identified i n sections 27 and 28 of the Act.  
(187) Of particular relevance when considering biosecurity clearance for  consignments of plants for 
planting is section 27(2)(a) of the Act. This section states that an inspector must not give a 
clearance for goods if he or she is aware of any circumstances or documents associated with the goods that makes it unwise for them to be given a biosecurity clearance. As part of verifying that 
no such circumstances apply to high value crops that may have been in post entry quarantine for a prolonged period, MPI will check the emerging risk register before goods are cleared. If any newly identified risks have been identified MPI may require additional phytosanitary measures to be applied to ensure that risk has been appropriately  managed before plants are cleared.  This 
may result in plants having to remain in quarantine for an additional period of time, whilst newly identifi ed risk is managed.