Import risk analysis: Tissue 
culture of  Alstro emeria  spp. from 
India and South Africa  
 
Biosecurity New Zealand Paper No: 2021/….. 
 
 
 
ISBN No:  
ISSN No:  
 
 
Version 1.0  
 
 
[2nd September  2021 ] 
 Disclaimer  
While every effort has been made to ensure the information in this publication is accurate, the Ministry 
for Primary Industries  does not accept any responsibility or liability for error of fact, omission, 
interpretation or opinion that may be present, nor for the consequences of any decisions based on this 
information.  
The material and information contained in the import risk analysis  is preliminary  and will be updated 
based on any feedback received during consultation on any related import health standards or any 
further feedback that may be provided by  internal or external experts.   
 
 
 
 
 
 
 
 
 
 
Recommended citation:  
MPI (20 21) Import Risk Analysis:  Tissue culture of Alstroemeria spp. from India and South Africa . 
Version 1. 0. September  2021. Ministry for Primary Industries, New Zealand.  
 
 
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WELLINGTON  6140  
Email: brand@mpi.govt.nz  
Telephone: 0800 00 83 33  
Facsimile: 04 -894 0300  
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Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, July 2021  • i  
 
 
Import risk analysis: Tissue culture of Alstroemeria spp. from India and South Africa   
 
Version 1 .0 
 
September  2021  
 
Approved for general release  by: 
Associate Director, Animal and Plant Health Directorate  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
© Crown Copyright - Ministry for Primary Industries  
   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • ii Version information  
Version number  Comments  Date of approval  
1.0 Approved by Associate Director, Animal & Plant Health  2nd September 2021  
    
New Zealand is a member of the World Trade Organisation and a signatory to the Agreement on the 
Application of Sanitary and Phytosanitary Measures (“The Agreement”). Under the Agreement, 
countries must base their measures on an International Standard or an  assessment of the biological 
risks to plant, animal or human health.  
This document provides a scientific analysis of the risks associated with the importation o f 
Alstroemeria tissue culture.  It assesses the introduction of pests and pathogens associated with 
Alstroemeria tissue culture  imported from India and South Africa  and assesses the potential impacts 
of those organisms should they enter and establish in New Zealand.  The document has been 
reviewed by subject matter experts from the Risk Assessment Group and the Plant Health and 
Environment Laboratory (PHEL ) and  is now released publicly  for feedback . Any significant new 
science information received that may alter the level of assessed risk will be included in a review , and 
an updated version released.   
 
   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, July 2021  • iii Executive summary  
Background  
This import risk analysis (IRA) was initiated following a request from importers to add India and South 
Africa to the approved countries listed in the Alstroemeria schedule of the nursery stock import health 
standard . The request was prompted by the fact that m any global plant breeders have moved their 
plant production operations to developing countries, such as India and South Africa .  
This (IRA) assesses the biosecurity risks associated with the importation of  tissue cult ure of 
Alstroemeria  for propagation  and planting  from India and South Africa . The IRA covers species of 
Alstroemeria listed on the plant biosecurity index (PBI)  that are  approved for importation as nursery 
stock to New Zealand: Alstroemeria aurea , A. gayana, A. haemantha, A. hookeri, A. ligtu, A. 
pelegrina, A. psittacine, A. pulchella, A. pulchra.  
Pathways and c omm odities covered  in this IRA are provided in Table 1. 
Table 1: List of  pathways and commodities assessed in this IRA  
Commodity type  Pathway description  
Plants for planting (Tissue culture)   Tissue culture, or plants in vitro , of Alstroemeria 
species eligible for import to New Zealand , 
sourced from India or South Africa. The tissue 
culture must meet the requirements under 
‘standard entry conditions for tissue cultures’, 
section 2.2.2 in the MPI nursery stock standard.    
 
Objectives  
Biosecurity New Zealand’s objectives in developing an IRA  are to : 
1. Identify pests and diseases that present a  level of risk to New Zealand on the commodity 
and pathway included in the scope . 
2. Evaluate the effect  of risk management measures on the level of  risk identifie d. 
Completion of 1 and 2 above will ensure that the  risk managers have the information they need to 
recommend appropriate and effective risk management measures . 
IRA Scop e 
The scope of the IRA considers the following key questions:  
• What are the  risk management questions?  
• What is the detailed commodity and pathway description s? 
• What measures  will be applied that have been justified by existing  risk assessments  
Risk management question s  
Description  Does each assessed pest  or disease : 
1. meet the criteria to be a quarantine pest1, and  
2. meet (or potentially meet) the criteria to be considered for additional 
measures ( i.e., over and above basic measures)?  
For the pests and diseases that  meet or potentially meet the criteria to be 
considered  for additi onal measures, the following questions are considered:  
                                                      
1 A quarantine pest is an organism that is not present in New Zealand (or is present but still represents a biosecurity risk, e.g., is 
capable of vectoring pathogens that ae not present in New Zealand) and is capable of establishing and causing harm in New 
Zealand.   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • iv What measures/options are used globally to manage these pests and 
diseases on  Alstroemeria tissue culture or tissue culture of other host 
plants ? 
 
Detailed c ommodity description  
Commodity Description  The commodity that is being assessed is: Tissue culture, or plants grown 
in vitro, of Alstroemeria species listed on the PBI and  permitted for import 
into New Zealand , for propagation that have been produced using 
standard methods for tissue culture . The tissue culture must meet the 
‘standard entry conditions for tissue cultures’ required under section 2.2.2 
in the  MPI nursery stock standard. Species covered in this IRA are: 
Alstroemeria aurea  (=A. aurantiaca ), A. gay ana, A. haemantha, A. 
hookeri, A. ligtu , A. pelegrina, A. psittacine, A. pulchella and A. pulchra.   
 
Currently Applied  measures  
Description of applied 
measures  The tissue culture will undergo measures as described under section 
2.2.2 of the MPI nursery stock standard: “Entry conditions for t issue 
cultures ”.  
Under these conditions, there are requirements for labelling and 
cleanliness , but there are no requirements for the plants to be grown in 
post entry quarantine.  
 
 
IRA m ethodology  
The IRA methodology used in this IRA is described in more detail in BNZ Guidance Document for 
Import Risk Analysis Version 1.0 .   
The IRA process involves three principal stages:  
1. Hazard identification  
2. Pest risk assessment  
3. Evaluati on of  risk management options  
1. Hazard identification  
A hazard is a pest  or disease  that: 
• is not present in New Zealand ( or is present but still represents a biosecurity risk, e.g., is 
capable of vectoring pathogens that are not present in New Zealand) ; 
• has the ability to establish and cause harm in New Zealand ; and 
• is associated with the risk goods  intended for import  and the import pathway.  
Hazard identification (hazard ID) is the process where, depending on the scope of the IRA, a list of 
pests and diseases  potentially associated with the commodity is compiled and then assessed again st 
specified risk evaluation criteria , to determine which pests and diseases  require further assessment.  
The risk evaluation criteria  for this IRA  are: 
• The pest or disease is present in India and/or South Africa.  
• The pest or disease is associated with Alstroemeria tissue culture that meets the standard 
conditions for entry of tissue culture under section 2.2.2 of the MPI nursery stock import health 
standard .  
• The pest or disease has the potential to establish and spread in the New Zealand 
environment; and   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, July 2021  • v • The pest or disease h as the potential to  cause harm in New Zealand.  
The r esults of the hazard ID  provide the following : 
• Pests and diseases that require further assessment ; listed in Table 2 and addressed in the 
pest risk assessment section below. Th ey were identified as being associated with the 
commodity, present in at least one exporting country and not likely managed by compliance 
with the commodity description and basic measures.   
• Species  that did not meet the criteria to require pest risk assessm ent. These are  listed  in 
Appendix 1 , along with the rationale for excluding them . 
2. Pest risk assessment  
The purpose of risk assessment is to determine the level of risk that pests and diseases (identified at 
the hazard ID stage as requiring further assessme nt) pose to New Zealand. Specifically, the pest risk 
assessment (PRA) concludes whether the pest or disease meet s the risk evaluation criteria to be 
considered for  additional measures  over and above basic measures.  
Pests and diseases that meet (or potentially meet ) the criteria to be considered  for additional 
measures are those that:  
• are associated with Alstroemeria tissue culture that meets the standard conditions for entry of 
tissue culture under section 2.2.2 of the MPI nursery stock import healt h standard ,   
• are present in India or South Africa , and  
• have the potential to establish and cause harm in New Zealand.  
The PRA addresses the following : 
• The overall risk of the pest or disease  (without the application of risk management measures)  
• Likelihood of entry , which considers : 
o The strength or frequency of the association with the host  
o How the application of basic measures  affects the likelihood of entry   
• Likelihood of exposure and establishment , which considers : 
o The ability of the pest or di sease to move from imported tissue culture  into a suitable 
environment to allow establishment (exposure)  
o The suitability of the New Zealand environment for the pest or disease (including 
climate, host plants and vectors)  
• The potential impacts in New Zealand:  
o Economic impacts on economically  important plants (symptoms on individual plants, 
crop yield, costs of management practices, trade restrictions , etc.) 
o Environment al impacts on native plants and ecologies  
o Human health, sociocultural  
• The overall ris k of the pest or disease after management measures are applied  
 
3. Management considerations  
When a  PRA concludes that a pest or disease meets the criteria to be considered  for additional 
measures, information relevant to management options, where available in the literature, have  been 
evaluated . This information pertains to options such as: 
• Pest-free areas  (PFAs) or pest -free places of production  (PFPPs)  
• Diagnostic testing , e.g., molecular testing using Polymerase chain reaction (PCR)  
• Growing season inspecti on in post entry quarantine  (PEQ)   
 
Summary of IRA conclusions  
A summary of the  pests and diseases  for which PRAs were carried out, and the PRA conclusion with 
respect to potential measures options, is provided in  
  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • vi  
Table 2. 
 
 
 
 
Table 2: Summary of IRA conclusions based on pest or disease groups or species for which 
PRAs were carried out . 
Pest /disease  group  Species requiring PRAs  Overall Level of assessed 
risk to New Zealand  Management 
considerations2 
Bacteria  ‘Candidatus phytoplasma 
asteris’  Moderate  PFA, PFPP , heat 
treatment and PCR  
testing  
Clover phyllody 
phytoplasma  Low PFA, PFPP, heat 
treatment and PCR 
testing  
Viruses  Broad bean wilt virus 2  Moderate  PFA, PFPP, PCR 
testing  
 
  
                                                      
2 See definitions of abbreviations in [e.g., Appendix 2 ]   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, July 2021  • vii Import Risk Analysis  
 
Contents  Page 
 
1. Risk analysis process  8 
1.1 Overview of the risk analysis process  8 
1.2 Hazard identification  10 
1.3 Risk assessment  11 
1.4 Risk assessment criteria  11 
1.5 Assessment of uncertainties  11 
1.6 Review and consultation  12 
1.7 References for Chapter 1  12 
2. IRA scope and information  13 
2.1 Descriptions of the commodity and pathway  13 
2.2 General information related to likelihood of entry  14 
2.3 General information related to  likelihood of exposure and establishment  14 
2.4 General information related to impacts of pests and diseases  18 
2.5 References for Chapter 2  19 
3. Hazard identification  23 
3.1 References for Chapter 3  23 
4. Risk Management Options  24 
4.1 References for Chapter 4  25 
5. Pest risk assessments: Bacteria  26 
5.1 ‘Candidatus Phytoplasma asteris’  26 
5.2 Clover phyllody phytoplasma  39 
6. Pest risk assessments: Viruses  52 
6.1 Broad bean wilt virus 2  52 
Appendix 1.  Summary of taxa excluded at hazard identification  69 
Appendix 2.  Glossary and Abbreviatio ns 77  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 8 1. Risk analysis process  
1.1 Overview of the  risk analysis process  
The Biosecurity New Zealand (BNZ) process for undertaking an import risk  analysis (IRA) builds on 
the existing international frameworks for risk analysis under the World Organisation for Animal Health 
(OIE) and the International Plant Protection Convention (IPPC), and extends the scope, under the 
SPS Agreement, to include all of the values required by the Biosecurity Act (1993)3.  
The Biosecurity Act (1993) requires a chief technical officer to begin the process of developing an IHS 
by: “analysing or assessing the risks associated with importing a class or description of goods”4. While 
the Biosecurity Act does not state how the risks are to be assessed or analysed, it does state that the 
chief technical officer must have regard to certain matters when developing an IHS for 
recommendation to the Director -General. A number of thes e are part of an IRA as described by the 
OIE and IPPC:  
• The likelihood that the goods will import organisms5 
• The nature of the organisms that the goods may import  
• The possible effect on human health, the New Zealand environment6, and the New Zealand 
econom y, of the organisms that the goods may import  
• In relation to requirements proposed for inclusion in an IHS, the extent to which the 
requirements reduce or manage the likelihood or impacts of adverse effects from organisms 
that may be imported on or in asso ciation with goods7 
The World Trade Agreement on the Application of Sanitary and Phytosanitary Measures (SPS 
agreement) states that phytosanitary measures must be supported by risk assessment and not 
maintained without sufficient evidence. That is, to require additional measures, MPI must have 
evidence that a pest or pathogen  would not be sufficiently managed by compliance with the 
commodity description . An import risk analysis  is also a relevant factor in how a country meets its 
obligations under ot her agreements such as the Convention on Biological Diversity (CBD) . Under the 
CBD, countries must consider environmental impacts in decision -making and prevent the introduction 
of, and control or eradicate alien species that threaten ecosystems, habitats,  and species.  
The main output of an IRA is summarised scientific evidence that is used to develop  or review an 
import health standard (IHS) under the Biosecurity Act (1993). An IHS specifies the requirements to 
be met for the effective management of risks associated with importing risk goods8. 
The individual steps in the process for developing an IRA are the same for both the OIE and IPPC. 
However , the standards, guidelines , and recommendations for animal health (sanitary) and plant 
health (phytosanitary) measures are developed by different international bodies. This means that 
there are  differences in the detail of how IRA is done for animal health (OIE) and plant health (IP PC). 
The MPI process and methodology for undertaking an IRA is summarised in  Figure 1. The MPI 
                                                      
3Biosecurity Act section 24(4)(b)(iii) “…human health, the New Zealand environment, and the New Zealand economy…” As 
defined in section 2(1), environment includes (a) ecosystems and their constituent parts, including people and their 
communities; and (b) al l natural and physical resources; and (c) amenity values; and (d) the aesthetic, cultural, economic, and 
social conditions that affect or are affected by any matter referring to paragraphs (a) to (c).   
4Section 23(1) Biosecurity Act 1993  
5From Section 2( 1) Biosecurity Act 1993:  “organism —(a) does not include a human being or a genetic structure derived from a 
human being:  (b)includes a micro -organism:  (c) subject to paragraph (a), includes a genetic structure that is capable of 
replicating itself (whether  that structure comprises all or only part of an entity, and whether it comprises all or only part of the 
total genetic structure of an entity):  (d) includes an entity (other than a human being) declared by the Governor -General by 
Order in Council to be an  organism for the purposes of this Act:  (e) includes a reproductive cell or developmental stage of an 
organism:  (f) includes any particle that is a prion ” 
6From section 2(1) Biosecurity Act 1993, “ environment includes — (a) ecosystems and their constituent parts, including people 
and their communities; and (b) all natural and physical resources; and (c) amenity values; and (d) the aesthetic, cultural, 
economic, and social conditions that affect or are affected by any matter referred to in paragraphs (a) to ( c)” 
7Section 23(4)(b) and (d) Biosecurity Act 1993  
8 Section 22(1) Biosecurity Act 1993.  
  
9 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  process is equivalent to the process for plant health ris k analysis in the relevant International 
Standards for Phytosanitary Measures (ISPM s) under the IPPC9 (the main differences being in 
terminology).  
 
 
Figure 1: BNZ process and methodology for undertaking an import risk analysis  
  
                                                      
9ISPM2: Framework for Pest Risk Analysis 
https://www.ippc.int/static/media/files/publication/en/2019/05/ISPM_02_2007_En_Framework_PRA_2019 -04-
30_PostCPM14_InkAm.pdf an d ISPM 11: Pest Risk Analysis for Quarantine Pests 
https://www.ippc.int/static/media/files/publication/en/2019/05/ISPM_11_2013_En_PRA_QPs_2019 -04-
30_PostCPM14_InkAm.pdf.  
 
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 10 1.2 Hazard identification10 
Hazard identification is the process for identifying pests and diseases  that are associated with 
imported risk goods and which have the ability to cause harm to New Zealand. The process consists 
of compiling a list of potential hazar ds and then assessing them against criteria to see whether they 
warrant further consideration. The ha zard identification answers two different questions:  
• Does the species meet the criteria to be considered a biosecurity risk for New Zealand?  
• Is the species potentially associated with the commodity that is being assessed?  
The criteria for a quarantine pest for New Zealand are derived from the Biosecurity Act and the IPPC 
and OIE . These criteria are:  
• Is the pest or disease absent from New Zealand ? 
• OR if the pest or disease present in New Zealand , does it meet one of  the following criteria?  
o The species is under official control . 
o The species is a vector of a quarantine pest or disease . 
o There are subspecific taxa (subspecies, varieties, strains , etc.) within the pest 
species that are an increased risk to New Zealand compared with those already 
present . 
o There are other factors that would mean that the pest or disease may still be of 
concern in associated with imported goods ( e.g., increased exposure to people 
through imported goods11). 
• AND does the pest or disease have the potential to establish in New Zealand and harm 
“human health, the New Zealand environmen t, and the New Zealand economy12”? 
Association with the commodity is based on: 
• association with the commodity species or genus ; 
• association with the specific parts of the commodity ; and 
• whether a particular pest or disease will stay associated with a commodity during preparation 
and/or transit to New Zealand  – for example , a larg e flying insect is unlikely to stay on a piece 
of fruit when it is picked.  
For the hazard identification:  
a) A list of potential  hazards must be compiled using the methods documented in the IRA 
plan. 
b) Potential  hazards must be assessed against criteria which m eet relevant international 
standards and the requirements of the Biosecurity Act 1993 . 
c) The hazard identification conclusions must be documented and supported by suitable 
evidence . 
Different approaches may be  adopted  for compiling  and presenting  the list of potential hazards , 
depending on the information needed for  pests or diseases  in each pest/disease  group . The approach 
for each group may be  determined in the project plan , once the risk management question s and risk 
evaluation criteria have be en established. The specific approaches to hazard identification used in 
this import risk analysis are discussed further in section 3.  
  
                                                      
10 Under the IPPC, the hazard identification process is known as pest categorisation in  ISPM 2 and ISPM 11.  
11 One example is venomous spiders on fresh fruit. Even if present in a country, there may be a higher likelihood of people 
getting bitten if the spiders are associated with fruit sold at a supermarket.  
12 Biosecurity Act 1993   
11 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  1.3 Risk assessment  
At the end of hazard identification, a list of hazards that require risk assessment is compiled . A risk 
assessment evaluates the likelihood of introduction (entry, exposure and establishment) and 
consequence for a particular hazard, as well as the uncertainty in the conclusions. The SPS 
agreement describes the factors to consider  when assessing risk . These factors include:  
• available scientific evidence;  
• relevant processes and production methods;   
• relevant inspection, sampling and testing methods;  
• prevalence of specific diseases or pests ; 
• relevant ecological and environmental conditions ; and 
• potent ial damage in the event of the entry, establishment or spread of a pest  or disease . 
A qualitative approach is suitable for the majority of import risk analyses and is currently the most 
common type of assessment undertaken to support the development and re view of import 
requirements.  
The risk assessment stage of the IRA process:  
a) must be documented and supported by suitable evidence , and  
b) must answer the risk management question by following agreed definitions or criteria.  
1.4 Risk assessment criteria  
For each of  the likelihoods of entry, exposure, establishment, and the level of consequences, the 
ranking scales listed in the table below  will be used .  
Scale  Criteria  
Very High  Well above the normal or average level  (used for consequences and final risk score 
only)  
High Extending above the normal or average level  
Moderate  Around the normal or average level  
Low Less than average, coming below the normal level  
Very low  Close to insignificant  
Negligible  Not worth considering; insignificant  
 
1.5 Assessment of uncertainties  
The SPS agreement states that measures must be applied only to the extent necessary  and must be 
supported by  sufficient scientific evidence13. If there is insufficient evidence indicating that a n 
organism  meets the criteria for requiring additional measures (the risk evaluation criteria),  then the 
lack of evidence suggests that it does not meet the criteria  to be a hazard  (see section 1.3.5) . 
However, in some cases there may be good reason to consider a pest or disease  even when 
evidence is insufficient (e.g. similarity to known pests or diseases ), and that pest or disease  may be 
assessed further . If there is insufficient evidence but significant uncertainty, then  the decision maker 
may appl y measures, but under those circumstances , the measures are provisional and further  
conditions  may be required14.  
Therefore , documenting significant uncertainty is an essential part of a risk assessment. Uncertainties 
due to  contradictions in the evidence or a lack of evidence are documented in the IRA. Where the risk 
                                                      
13 SPS Agre ement 1995 Article 2.2  
14 SPS Agreement 1995 Article 5.7   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 12 assessment identifies significant uncertainty affecting the conclusion, this is indicated in the wording 
of the conclusion  for each likelihood and consequence. In this IRA, uncertainty and the  rationale for 
the uncertainty rating will be stated in the text as follows:  
Scale  Criteria  
High • Scarce or no data available; evidence provided in unpublished reports of unknown 
authenticity; or  
• Few observations and personal communications; and/or  
• Authors’ or experts’ conclusions vary considerably  
Moderate  • Some or only incomplete data available; evidence provided in small number of 
references; authors’ or experts’ conclusion vary; or  
• Limited evidence from field/lab observations; or  
• Solid and complete data available from other species that can be extrapolated to 
the species being considered  
Low • Solid and complete data available; strong evidence in multiple references with 
most authors coming to the same conclusions; or  
• Considerable and consistent experience from field observations  
 
1.6 Review and consultation  
Expert  review is a fundamental component of a risk analysis to ensure the analysis is based on the 
most up -to-date and credible information available.  
The IRA is reviewed internally to check that it is based on the best available and most credible 
information, that the document is clear and logical, that assumptions are valid and that conclusions 
are consistent with the evidence, and with relevant conclusions in other assessments. External review 
may be done if suitable experts are not available within MPI.  
1.7 References for Chapter  1 
FAO (1995) Guidelines for pest risk analysis . International Standard for Phytosanitary Measures No. 
2. Published by FAO on behalf of the Secretariat of the International Plant Protection Convention 
(IPPC); Rome, Italy.  
FAO (2013) Pest risk analysis for quarantine pests . International Standard for Phytosanitary 
Measures No. 11. Published by FAO on behalf of the Secretariat of the International Plant Protection  
Convention (IPPC); Rome, Italy.  
WTO (199 5) World Trade Organization (WTO) Sanitary and Phytosan itary Measures Agreement 
(SPS). www.wto.org/english/tratop_e/sps_e/sps_e.htm . 
   
13 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  2. IRA scope  and information  
This import risk analysis (IRA) has been developed in response to a request to add India and South 
Africa to the list of approved countries  in the import health standard for nursery stock (IHS 155.02.06) , 
from which tissue culture of Alstroemeria  species can be imported into New Zealand . The purpose of 
the IRA is to identify and assess biosecurity risks associated with tissue culture of Alstroemeria  
species permitted for import into New Zealand , and to analyse risk management options t o inform 
decisions on risk management.  
The objective of the IRA is to:  
a. identify pests and diseases  which are associated with the commodity and may require 
measures ; 
b. assess these pests and diseases  using a method that provides sufficient evidence about the 
biosecurity risks for a robust and transparent decision on whether measures are required to 
manage these pests  and diseases; and  
c. assess options for managing the identified risks to an appropriate level.  
For any parti cular risk good15, there is a commodity definition  used in an IRA ; that is, the physical 
parts that make up the commodity, and  the commodity description (the condition  under which it is to 
be imported ). The commodity description is important as many pests a nd diseases may not be 
associated with a commodity that is defined in a certain way (e.g. more pests may potentially be 
associated with a commodity definition of fresh beans for consumption than a commodity definition of 
frozen beans for consumption).  
2.1 Desc riptions of the c ommodity and pathway  
This risk analysis considers the effects on the New Zealand economy, environment , society  and 
human health16 from organisms potentially associated with the importation of Alstroemeria tissue 
culture from India  and South  Africa . A detailed description of the commodity and pathway is provided 
in Table 3 . 
Table 3: Detailed description of the commodity and the pathway(s) of entry to New Zealand  
Commodity description  
The Alstroemeria species assessed are those permitted entry to New Zealand, as listed in the MPI Plant Biosecurity 
Index (PBI). At the date of publication, these species are as follows:  
Alstroemeria aurea                                         Alstroemeria pelegrina  
Alstroemeria gayana                                       Alstroemeria psittacina  
Alstroemeria haemantha                               Alstroemeria pulchella  
Alstroemeria hookeri                                     Alstroemeria pulchra  
Alstroemeria ligtu  
 
The commodity is defined as: tissue culture/plants in vitro of approved Alstroemeria species derived from aerial plant 
parts only , which meet the ‘entry conditions for tissue culture’ under section 2.2.2 of the MPI nursery stock IHS (MPI 
standard 155.02.06 ). These may include stems, shoots, leaves, terminal and auxiliary  buds, flowers, petiole segments, 
seeds, embryos , and endosperm. Organisms that are only known to be associated with other plant parts (e.g. root or 
basal stem tissue have not been assessed.   
 
Pathway  description  
                                                      
15 Regulated article under IPPC  
16 Specifically, this IRA covers sections 23(4)(b)(i), (ii) and (iii) of the Biosecurity Act:  
(i) the likelihood that the goods will import organisms:  
(ii) the nature of the organisms that the goods may import:  
(iii) the possible effect on human health, the New Zealand environment, and the New Zealand economy of the organisms that 
the goods may import   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 14 Alstroemeria tissue culture/plants in vitro from India and South Africa, which meet the ‘entry conditions for tissue culture’ 
under section 2.2.2 of the MPI nursery stock IHS (MPI standard 155.02.06) . The entry conditions include requirements 
for labelling and an accompanying phytosanitary certificate, however there is no requirement for the plants to be grown 
and observed in post entry quarantine. The container of plantlets is also inspected on arrival  at the New Zealand border.  
 
 
2.2 General information related to likelihood of entry  
The following aspects of the commodity and pathway description affect the likelihood that pests or 
diseases will enter New Zealand .  
The transfer of plants into tissue culture, and the subsequent multiplication of these plants in vitro , is 
considered to reduce the likelihood of insects or mites being present on plants in tissue culture to an 
acceptable level for the following reasons:  
• Minute invertebrates such as mites or thrips may be present in mother plant material 
(Bhagwat & Lane 2003), but the selection of small amounts of healthy tissue and its 
subsequent processing ( e.g., surface sterilisation) will minimise the likelihood of inse cts or 
mites being transferred into tissue culture;  
• debris (frass, moult skins etc.) associated with invertebrate activity, or the movement of 
invertebrates themselves onto the tissue culture medium, are likely to result in the growing 
medium becoming visu ally contaminated with bacteria or fungi (Bhagwat & Lane 2003 ; van 
Epenhuijsen & Koolaard 2004), and these cultures are likely to be discarded as a normal part 
of plant in vitro management;  
• Invertebrates and invertebrate damage are usually visually detectable, and plants are 
required to be inspected for visually detectable regulated pests.  
 
Depending on the individual characteristics of the species, f ungi and oomycetes may be associated 
with tissue culture. If the mother plant is infected with b acter ia, phytoplasmas,  or viruses , these 
pathogens may be associated with the resulting tissue culture and , therefore , have the potential to 
enter on the commodity.   
2.3 General information related to likelihood of exposure and establishment  
2.3.1 Potential for exposure   
When a pest or disease  arrives in a new area, it usually needs to find or come into contact with a host 
in order to establish. This is termed “exposure” in BNZ risk assessments.  
In the case of germplasm , imported plant material is  maintained in a habitat  favourable  for plant 
growth and is likely to be multiplied up to substantial numbers . Promoting the survival and persistence 
of the plant material also promotes the survival and persistence of the associated pathogens.  
2.3.2 Climate requirements for Alstroemer ia  
Alstroemeria species are native to South America, originating from Argentina, Chile and Brazil 
(Missour i Botanical Garden undated ; POWO 2021 ). They are summer -flowering, herbaceous 
perennials in temperate forests (Aizen 2001).  The genus is now grown around the world as an 
ornamental species (POWO 2021).  Alstroemeria is commercially grown throughout New Zealand 
(NZPPI pers. comm .).   
In the Australian state  of Victoria,  which has a similar climate to New Zealand,  Alstroemeria species 
have become succes sful weed s in numerous locations, particularly in shady, damp sites such as 
gullies (Agriculture Victoria 2020). Modelling , based on climate and land use , suggests that the 
potential distribution is much larger (Agriculture Victoria 2020).      
15 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  2.3.3 New Zealand climates  
New Zealand , in general , exhibits a mid -latitude oceanic temperate climate ( Cfb temperate with 
maritime climate in the Köppen classification (Köppen 1936 ; Rubel and Kottek 2010) ). Annual 
precipitation varies substantially due to topography, from d ry eastern and inland areas to very high 
precipitation (on a global scale) in west coast areas17. The driest New Zealand climates barely reach 
a conventional water deficit on average (although they can do so in extreme years and months).  The 
New Zealand climate ‘space’ can be visualised  as a three -dimensional simplified climate niche ( Figure 
2). This represents the average monthly temperature and precipitation for each month of the year for 
42 New Zealand climate stations.  
 
Figure 2.  Climate niches of N ew Zealand. Thin grey lines: average monthly temperature (1981 –2010) for 
42 New Zealand climate stations (data from NIWA (2020) ). Each polygon is composed of the 12 months of the 
year. Small black ellipse: average conditions for those 42 sites. Large ellip se: 95% inclusive ellipse.  
 
As a consequence of being a small landmass in a large ocean, New Zealand has  relatively low diurnal 
and seasonal temperature fluctuations (equable climate). Rainfall is close to evenly distributed 
between summer and winter. Thes e feature s are similar in equatorial climates.  However, there can be 
relatively rapid variations between days , as large weather systems alternate over the oceans. 
Although such variations may also occur in continental climates, a key difference for organis ms is the 
proximity of these variations to biological thresholds (such as frost).  
Unlike many Northern Hemisphere continental climates with reliable lengthy warm and cold periods, a 
small temperature variation in a mild oceanic climate means a more significant change in the number 
of days crossing threshold degrees , which may in some cases restrict the ability of some organisms to 
establish. This feature is also common to smaller land masses and mountains of the Southern 
Hemisphere, which is why , globally, some of the most similar climate conditions to New Zealand are 
in the montane regions of the Andean Yungas cloud forests and grasslands (Halloy et al. 2008) . This 
is reflected in high morphological similarities of adaptations (Halloy & Mark 1996) . 
                                                      
17 This summary is written with crop pests and diseases in mind, focusing  on the climate in inhabited and cultivated areas of 
New Zealand. Rainy outliers (e.g. Milford and Mt Cook) and high mountain climates are not considered, as they represent 
extremes with relatively low human and agricultural activity  
050100150200250300
-10 0 10 20 30precipitation, monthly (mm)
temperature, average monthly (oC) 
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 16 Together with tussock grasslands, temperate rainforests are the global biome  climate types most 
represented in New Zealand. The northernmost areas of New Zealand approximate subtropical 
temperature conditions, with an ability to grow a range of subtropical  plants.  
The northern part of New Zealand is the most climatically suitable for the establishment of new pests 
and diseases  coming from a subtropical/tropical climate. The area includes Kaitaia, Kerikeri, 
Whangarei, Auckland (New Zealand’s largest city) an d Tauranga. The latter two cities both contain 
large active seaports . 
The climate overlap between New Zealand and where a p est or disease has been reported can be  
assessed using the tool described in Phillips et al. (2018).   This tool is based on the compo site (or 
climate ) match index (CMI) CLIMEX -MCR of CLIMEX version 3.3. The tool allows the comparison of 
New Zealand’s general climate or climate of specific New Zealand locations , with areas where a p est 
or disease occurs overseas. The higher the CMI, the more similar the climate of the region  to which 
the CMI pertains and the New Zealand climate. A CMI of 0.7 or more , between the New Zealand 
climate and the existing range of the p est or disease , would  indicate a high likelihood of climatic 
suitability for that pest or diseases to establish in New Zealand  (Phillips et al. 2018).  
For many of the pests or diseases assessed, this tool is adequate to determine if New Zealand ’s 
climate is suitable for the pest or disease to establish.  A whole-world map with CMI data from Phillips 
et al. (2018)  is provide d in Figure 3 . When using the tool, the map can be enlarged to show more 
detail at a regional level.  
 
Figure 3: Climate match index (CMI). World climate similarities with all of New Zealand (Phillips et al. 
2018) . 
2.3.4 Shifting New Zealand climates with climate change  
The global climate is warming rapidly and will continue to warm even faster as a result of greenhouse 
gas emissions (IPCC_WGI 2013 ; Allen et al. 2018 ; WMO 2019) . Severa l stud ies have examined the 
effects of these changes on the New Zealand climate (NIWA 2017 ; MfE 2018) . Warming 
temperatures and changing precipitation patterns will affect existing biodiversity, pests and diseases, 
and will change the likelihood of establishment  of new arrivals  (Gerard et al. 2013 ; Kean et al. 2015) . 
 
17 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  However, climate change is not just a scenario for the future. Average New Zealand temperatures 
have risen substantially over the last century, with concomitant but more variable changes in 
threshold  and extreme conditions (including frosts, heatwaves, droughts, tropical storms, etc). Sea 
surface temperatures (SSTs) around New Zealand are closely correlated with atmospheric warming, 
and in recent decades (since 1981) , have been  rising in the order of 0.1–0.3°C per decade (Sutton & 
Bowen 2019) . This would equate to 1 –3°C per century, close to the modelled predictions for 2100. 
Such trends are , to some degree , hidden by inter -annual variability, but are already significant for the 
biota, agriculture , and human occupation.  
These ‘shifting goal posts’ may lead to some confusion when reading climate change scenarios. 
Climate scenarios are expressed as degrees of change up to 2100, for example , a 2°C increase. 
However , the baseline for that increase may n ot be explicit to the reader. The baseline is sometimes 
referred to as ‘conditions pre -industrial age’, or ‘beginning of 20th century’. Other times , it may be the 
‘1961 –1990 average’, or more recently , the ‘1981 –2010’ average. Because of the continuous cha nge 
since the pre -industrial period, the first baseline would lead to a 2 °C increase by 2100. However, 
adding the same 2 °C to a 1981 –2010 baseline would mean ~3 °C increase by 2100 in respect to pre -
industrial conditions.  
In New Zealand, some of the last few years have already approximated a 2 °C increase on pre -
industrial levels. Although cool years will still occur, for an organism , some conditions in some years 
already approximate some models for 2100.  Model scenarios for temperature increases for 2100 
depend on many factors, but most scientists now expect there is little chance of  keeping the  increases 
below 2 °C (Wallace -Wells 2019) . To illustrat e, exploring a conservative 2 °C average increase (as in 
NIWA scenarios18) and a 10 -mm monthly increase in precipitation allows us to investigate the 
consequences without making any judgement as to which is more likely.  
We can then consider the likelihood of such scenarios. To give an idea of how conservative a +2°C is, 
consider that  the average temperature in the last century has already climbed >1 °C above pre-
industrial values. As averages shift, so do the extremes of the distribution and the thresholds for 
frosts, degree days, etc. Note , for example , that the m idpoint of July 2009 –2018 is where extreme 
warm y ears were in 1928 –1937; the extreme has already  become the norm ( Figure 4)19. Moreover, 
the pace of increase is accelerating, greenhouse gas emissions are still rising, and a series of 
potential tipping points may soon be breached. Due to prolonged lag time s, the abrupt decline in 
emissions triggered from March 2020 due to the Covid-19 pandemic are not likely to affects trends in 
the next decades. If such declines were to continue , they could reduce the centennial temperature 
increase.  
                                                      
18 2°C is an 'in betwee n' of the 0.7 °C to 3 °C range of scenarios in NIWA: https://niwa.co.nz/our -science/climate/information -and-
resources/clivar/scenarios, 20171221. However, in more detail, https://ofcnz.niwa.co.nz/#/localCharts shows an increase to 
2100 of 2 °C (RCP 6) to 3 °C (RCP 8.5) annual mean (for six -model average) for Christchurch. Annual precipitation remains 
almost the same. Spring °C and mm follow the same pattern. Summer (DJF) increases less (1.5 °C to 2.3 °C). For rainfall, 
possible increases are around 10 mm; however , there will be considerable geographic variation, and this is only illustrative.  
19 Note that climatologists typically prefer to use 30 years to represent a climatic period. Decadal periods are, however, usefu l 
for biological systems, as a decade is a long  enough time to determine whether an organism can perish, establish or invade.   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 18  
Figure 4: Schematic normalised frequency distribution of mean monthly temperatures for July (left) 
and January (right) for Wellington, New Zealand. The blue line is 1928–1937, the orange line  2009–
2018. Calculated from NIWA National Climate Database ( https://cliflo.niwa.co.nz/ ). Note that actual 
frequency distributions tend to skew further right.  
As a result of such shifts, in future scenarios, frost s decrease substantially, by 30% (RCP 2.6) to 50% 
(RCP 8.520) for the y ear 2040 (MfE 2018) . 
2.4 General information related to impacts of pests and diseases  
2.4.1 Potential for spread  
Alstroemeria are relatively hardy plants ; tolerating drought, most soil types and able to overwinter in, 
temperate countries,  outdoors once established (RHS 2021). Therefore, plants may be grown in a 
range of areas in New Zealand, under different climatic conditions and in contact with many  other 
plant species.  Furthermore , Alstroemeria spp. are commonly grown by home gardeners, who are 
likely to be growing other plants that may be suitable hosts for any associated pathogens.  Therefore, 
climate and distribution within New Zealand are unlikely to restrict the potential spread and distribution 
of associated pests and diseases.   
Com mercially, Alstroemeria  plants are largely grown in New Zealand for cut flower  production , which  
are often grown under cover . The controlled climatic conditions may aid the establishment of some 
pathogens from warmer climates . However , growing under cover may also slow  the spread of any 
associated pests to other host plants  outside the protected environment .   
2.4.2 Potential impacts on related species  
There are no economic, socially , or culturally significant plant species related to Alstroemeria present 
in New Zealand. Furthermore, there are no native New Zealand species in the genus Alstroemeria 
(Breitwieser et al. 2010 ). There is one member of the family Alstroemeriaceae, Luzuriaga parviflora, 
that is native to New Zealand, however it is not a t hreatened species (Breitwieser et al. 2010 ).  
                                                      
20 In the latest IPCC report, RCPs (representative concentration pathways) are used to indicate emission scenarios, where 2.6 
and 8.5 are the lowest and highest (e.g. (IPCC_WGI 2 013; MfE 2018) ).  
 
19 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  2.4.3 Potential for economic impacts to the Alstroemeria industry  
 
Alstroemeria tissue culture is imported into New Zealand for the domestic nursery plant market as well 
as for cut flower produc tion.  
 
Data on the va lue of the domestic Alstroemeria plant trade  is not readily available . Numbers provided 
by New Zealand Plant Propagators Inc. (NZPPI ) suggest that for the large nursery producers, 
Alstroemeria accounts for around $1  million per year, with smaller nurseries valuing the crop at 
around $100,000.  
 
The production of Alstroemeria  for cut flowers has increased in New Zealand over recent years and is 
expected to continue to increase. The volume of Alstroemeria stems imported into New Zealand has 
decreased, with the production gap being met by New Zealand growers (NZPPI pers. comms.). The 
expected production of Alstroemeria plants is approx. 200 stems per square meter (Van Lier Nurseries 
Ltd. 2015 ). Therefore, the  approx imate  stem production in New Zealand would be around 5.6 million 
(200 stems x 28, 00m2). In New Zealand a five-stem bunch of Alstroemeria flowers retails for a 
wholesale value of $9.95 ( wholesaleflowers undated).  
 
Export phytosanitary certificate d ata from MPI, between 2011 and 2018, shows that Alstroemeria spp. 
have been exported  as cut flowers  to: American Samoa, Canada, Cook Islands, Fiji,  French 
Polynesia,  Guan , Japan, New Caledonia, Samoa, Singapore, USA, Vanuatu.  
2.5 References for Chapter 2  
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limes and lemons revealed by cytoplasmic and n uclear markers. Annals of Botany , 117(4): 565 –583. 
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23 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  3. Hazard identification  
A hazard is a pest or disease that is associated with imported risk goods and import pathways , and 
that has the ability to cause harm to New Zealand. Hazard identification (hazard ID) is the process 
where , depending on the scope of the IRA,  a list of pests and diseases  potentially associated with the 
commodity is compiled . Each  pest or disease is then assessed against specified criteria, in order to 
determine which species may not be managed by compliance with the commodity descri ption . The 
objective for hazard identification in this IRA is  to identify all pests and diseases  that meet the risk 
evaluation criteria for requiring additional measures , based on assessment against the risk evaluation 
criteria .  
For this IRA, the hazard i dentification focused on the following risk evaluation criteria:  
• Association with the commodity (tissue culture of Alstroemeria ); and  
• present in at least one exporting country (India and South Africa)  
The organisms considered were limited to bacteria (including phytoplasmas), viruses , fungi , 
oomycetes  and leaf infecting nematodes . Due to the points described in section 2.2, invertebrates 
(insects, mites and root infecting nematodes) are not considered to be associated with tissue culture 
derived from a erial plant parts. Therefore, they are not considered to require management measures 
beyond meeting the commodity description , and were excluded from the hazard ID.  
Hazard identification for this project used the following sources:  
• Google Scholar  
• Google  
• CABI C rop Protection Compendium (June 2021)  
• MPI emerging risk system database  
• EPPO global database  
• Relevant textbooks  
 
A list of species identified at the hazard identification stage is provided in Table 4. They were 
determined to be  associated with the commodity, present in India and/or South Africa,  and potentially 
not likely to be  managed by compliance with the commodity description ; therefor e requirin g further 
assessment (a Pest Risk Assessment) , The list of species not considered to be hazards is given in 
Appendix 1 .  
Table 4: Pest groups , with species that were progressed to risk assessment following initial  
hazard identification   
Pest or disease group  Pest s or diseases requiring Pest Risk Assessments  (PRAs)  
Bacteria  ‘Candidatus  Phytoplasma asteris’ 
Bacteria  Clover phyllody phytoplasma  
Virus Broad  bean wilt virus 2  
3.1 References  for Chapter 3  
CABI Crop Protection Compendium. Information on crop pests. https://www.cabi.org/cpc/  
EPPO Global Database. European and Mediterranean Plant Protection Organization (EPPO) 
database for all pest -specific information that has been produced or collected by EPPO. 
https://gd.eppo.int/  
   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 24 4. Risk Management Options  
The following risk management options are avai lable for consideration to manage  the pests and/or 
diseases identified by risk assessment as requir ing additional measures . 
Molecular testing -Polymerase chain reaction (PCR)  
Molecular diagnostic tests, such as PCR tests, are available for a range of pathogens  and are a 
reliable method for identifying specific pathogens in plant material. The success of  such methods may 
be reduced when sampling asymptomatic tissue, or if the pathogen is unevenly distributed, or of 
uneven titre throughout the plant  (International Plant Protection Convention 2016 ). To ensure 
sufficient titre, mother plants or tissue cultur e grown up in PEQ should be tested, rather than the 
tissue culture itself.    
Assurance of pest free area (PFA)  
The International Standards for Phytosanitary Measures  (ISPM)  number 4: Requirements for the 
establishment of pest free areas  (ISPM No 4) descri bes the requirements for the establishment and 
use of PFAs as a risk management option for meeting phytosanitary requirements for the import of 
plants. The standard identifies three main components or stages that must be considered in the 
establishment and  subsequent maintenance of a PFA:  
o Systems to establish freedom, and  
o phytosanitary measures to maintain freedom, and  
o checks to verify freedom has been maintained.  
Normally PFA status is based on verification from specific surveys such as an official delimi ting or 
detection survey. It is accepted internationally that organisms or diseases that have never been 
detected in, or that have been detected and eradicated from, an area should not be considered 
present in an area if there has been sufficient opportuni ty for them to have been detected. When 
sufficient information is available to support a PFA declaration, this phytosanitary measure is usually 
considered to provide a very high level of protection.  
Assurance of pest free place of production  (PFPP)  
Pest f ree place of production (PFPP) The International Standards for Phytosanitary Measures (ISPM) 
number 10: Requirements for the establishment of pest free places of production and pest free 
production sites  (ISPM No 10) describes the requirements for the establishment and use of pest free 
places of production as a risk management option for meeting phytosanitary requirements for the 
import of plants. A pest free place of production is defined in the standard  as a “ place of production in 
which a specific pest does not occur as demonstrated by scientific evidence and in which, where 
appropriate, this condition is being officially maintained for a defined period ”. Pest freedom is 
established by surveys and/or gr owing season inspections and maintained as necessary by other 
systems to prevent the entry of the pest into the place of production. When sufficient information is 
available to support a PFPP declaration, this phytosanitary measure is usually considered to  provide 
a high level of protection depending on the epidemiological characteristics of the organism or disease 
in question.  
Growth in  post entry quarantine  (PEQ ) 
Growing plants in PEQ, under prescribed conditions for a set growing period in order  to obser ve the 
development of any symptoms , is utilised as a measure on many nursery stock pathways (MPI 
standard 155.02.06).  For tissue culture material, plants are removed from the media flask and 
replanted into pots. The plants are then  grown under greenhouse c onditions throughout the year and 
inspected frequently by the facility operator for signs of regulated pests and diseases. Plants must be  
25 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  held in a greenhouse of an appropriate PEQ level in order to contain any potentially associated pests 
and diseases.   
4.1 References for Chapter 4  
International Plant Protection Convention (2016) ISPM 27 Diagnostic protocols for regulated pests DP 
12: Phytoplasmas . IPPC, FAO, Rome.  
ISPM No 4 (1995) International Standards for Phytosanitary Measures number 4: Requirements for 
the establishment of pest free areas  
ISPM No 10 (1999) International Standards for Phytosanitary Measures number 10: Requirements for 
the establishment of pest free places of production and pest free production sites  
MPI Standard 155.02.06 Importation of Nursery Stock https://www.mpi.govt.nz/dmsdocument/1152 -
Nursery -Stock -Import -Health -Standard  Accessed 1 July 2021  
 
 
   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 26 5. Pest risk assessments: Bacteria  
5.1 ‘Candidatus Phytoplasma asteris ’ subgroup B  
‘Candidatus Phytoplasma asteris’, and related phytoplasmas, affect plants by causing extensive 
abnormalities in plant growth and development, suggestive of a profound disturbance in the plant 
hormone balance. Typi cal symptoms on herbaceous plants include leaf yellowing, stunting and 
proliferation of auxiliary shoots (witches’ -broom) virescence of flowers (abnormal green colouration in 
shoots and leaves) and sterility, as well as small and deformed leaves.  
5.1.1 Taxonomic description  
Scientific name: ‘Candidatus Phytoplasma asteris’  subgroup B  
Order/Family: Acholeplasmatales/Acholeplasmataceae  
Other names include:  16SrI subgroup B, 16SrI -B, aster yellows subgroup B   
Taxonomic notes : Phytoplasmas form a distinct clade in the Class Mollicutes. The phytoplasma 
clade has been proposed to represent at least a genus, with each subclade (16S rRNA group) 
proposed to represent at least one species (Gundersen et al. 1994). The ‘ Candidatus  Phytoplasma 
asteris’ group (16SrI)  is the largest of these groups, but it has also been divided into subgroups (A, B, 
C, D, E and others ) Lee et al. 2004; Zhao et al. 2010.  
The species concept is defined within the phytoplasmas (IRPCM 2004), but the appropriate level at 
which to conduct a  risk assessment is often unclear. Since the subgroups of the ‘ Ca. P. asteris’ 16SrI 
group phytoplasmas appear to represent distinct phylogenetic lineages, differing in distribution and 
host range, Lee et al. (2004) suggest that for quarantine purposes it would be appropriate to consider 
them separately.  
Subgroup B is widespread and diverse. There are dozens of isolates within this subgroup, described 
from different hosts in different regions (Lee et al. 2004). It is unclear whether any of these also diffe r 
in host range, distribution or other properties that may affect a risk analysis. It is assumed here that 
they do not differ to any significant degree, but further information characterising variation within ‘ Ca. 
P. asteris’ subgroup B may affect the resu lts of this risk analysis.  
5.1.2 Summary of IRA conclusions  
The following table contains a summary of risk assessment against the risk assessment criteria : 
Criteria  Rating Uncertainty  
The l ikelihood of entry on the commodity , given the pathway description  Low High 
The likelihood of transferring  from the imported commodity onto a suitable host  High Low 
The likelihood of establishing in the New Zealand  environment  Moderate  Moderate  
Impacts on the New Zealand economy, environment, health and society  Moderate  High 
Overall Level of assessed risk to New Zealand  Moderate  Moderate  
 
Given the arguments and evidence presented : 
• ‘Candidatus Phytoplasma asteris’  subgroup B  meets the criteria to be a hazard for New 
Zealand  on imported Alstroemeria tissue culture  because  it: 
o is not present in New Zealand,  
o has the potential to establish and spread in New Zealand ,   
27 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  o has the potential to  cause harm to New Zealand , and  
o has been isolated from Alstroemeria sp. and has biological characteristics which 
mean it has the potential to be associated with the commodity.  
• ‘Candidatus Phytoplasma asteris’  subgroup B poses a n overall  moderate  risk on Alstroemeria 
tissue culture  imported to New Zealand because  it: 
o has a low likelihood  of entering New Zealand on Alstroemeria tissue  culture  from 
India and South Africa  (with moderate  uncertainty) as: 
- hosts infected with ‘ Ca. P. asteris’ subgroup B can be asymptomatic and may 
be used for the production of tissue culture.  
- phytoplasmas systemically infect plants, and micropropagation (tissue 
culture) is a known method by which phytoplasmas are transmitted.  
- there is only one report of the phytoplasma being associated with 
Alstroemeria  sp., and therefore, Alstroemeria  does no t appear to be a 
common host of the phytoplasma.   
 
o has a high likelihood  of transferring  from Alstroemeria tissue culture  to an appropriate 
host in New Zealand  (with low uncertainty) as: 
- nursery stock is maintained in a manner favourable for plant growth,  and is 
likely to be multiplied up to substantial numbers  
- promoting the survival and persistence of the plant material also promotes 
the survival and persistence of the associated pathogens.  
 
o has a moderate  likelihood  of establishing in New Zealand  (with moderate  uncertainty) 
as: 
- ‘Ca. P. asteris’ subgroup B can systemically infect a host plant as long as the 
plant remains alive  and,  
- it infects species that are commonly grown in New Zealand .   
- a large portion of imported Alstroemeria plants are sold to home gardeners 
and, therefore , would likely be planted near other host plants.    
- although known vectors are not present in New Zealand, insects that may be 
able to act as vectors are present.  
 
o may cause moderate  overall impacts on New Zealand  (with high uncertainty) as: 
- hosts of the phytoplasma include economically significant crops including 
grapes, apples, onions and potatoes.  
- typical symptoms of the pathogen affect flowers, which are likely to have 
significant impacts to the cut flower, seed and ornam ental industries.  
- phytoplasmas have been associated with diseased environmental plants in 
New Zealand, therefore there is the potential for environmental impacts.  
- the extent of impacts, and hosts  that may be affected , depends on the 
vectors present in New Zealand, their host range and their ability to transmit 
the phytoplasma.  
 
• The following measures reduce the overall risk of ‘Candidatus  Phytoplasma asteris’  subgroup 
B on Alstroemeria tissue culture : 
o PCR testing  of mother plants , or tissue culture grown in post entry quarantine,  would 
reduce the overall risk to low with low uncertainty as , although PCR testing of  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 28 asymptomatic plants reduces the overall risk of phytoplasmas entering on nursery 
stock, there is the potential for false negatives. Therefore, PCR testing does not 
reduce the risk to negligible.   
o Heat treatment of mother plants, followed by PCR testing would reduce the overall 
risk to negligible with moderate uncertainty, due to the lack of Alstroemeria spp. or 
‘Ca. P. asteris ’ specific data.   
o Assurance of pest free area  would reduce the overall risk to negligible with low 
uncertainty.  
o Assurance of pest free place of production would reduce the overall risk to negligible 
with low uncertainty.    
o Growth of  the plants in post entry quarantine is insufficient to reduce the overall risk 
of ‘Ca. P. asteris’ due to the potential for asymptomatic infection.    
5.1.3 Hazard  identification  
• ‘Candidatus Phytoplasma asteris’  subgroup B  is not known  to be present in New Zealand:  
o ‘Ca. P. asteris’  subgroup B  is not listed in Veerakone et al. (2015) or PPIN (2021).  
o ‘Ca. P. asteris’ is a regulated pest (ONZPR 2021) . 
• ‘Candidatus Phytoplasma asteris’  has the potential to establish and spread  in New Zealand:  
o ‘Ca. P. asteris’ subgroup B infects species that are commonly grown in New Zealand, 
therefore suitable host would be present in the New Zealand environment.  
o Although known vectors  are not present in New Zealand, insects within a known 
vector genus are present and may be able to vector the phytoplasma.  
• ‘Candidatus Phytoplasma asteris’  subgroup B  has the potential to cause harm  in New 
Zealand:  
o It has a broad host range, including commercially important crops in New Zealand.  
o Symptoms  induced by the phytoplasma  are likely to reduce yields of crops, resulting 
in losses.  
• ‘Candidatus Phytoplasma asteris’  subgroup B  has the potential to be associated with 
Alstroemeria tissue culture :  
o ‘Ca. P. asteris’ subgroup B has been isolated from Alstroemeria plants, including from 
micro -propagated shoots (Bertaccini et al. 1996).  
o Phytoplasmas are systemic pathogens and can be associated with all types of 
nursery stock.   
o Therefore, the pathogen may be associated with the host and commodity.   
Given the arguments and evidence above, ‘Ca. P. asteris’  subgroup B meets the criteria to be a 
hazard  on Alstroemeria tissue culture  imported to  New Zealand  
Risk assessment  
5.1.4 Biology and epidemiology of ‘Candidatus Phytoplasma asteris’  subgroup B  
Phytoplasmas are phloem -limited bacteria that lack cell walls and cannot be cultured (Lee et al. 2000, 
Bertaccini 2007). They are associated with a wide range of symptoms affecting all plant parts; typical 
symptoms include ‘little leaf’, abnormal root grow th, overall stunting, shoot proliferation, leaf yellowing, 
flower phyllody (abnormal development of flowers into leafy structures) and virescence (abnormal 
green coloration in shoots and flowers), as well as a general decline that is sometimes fatal (Agrio s  
29 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  2005). However, it is not uncommon for them to be associated with asymptomatic plants (Bertaccini 
and Lee 2018).   
Transmission  
There are two main mechanisms of transmission known for phytoplasmas: propagation or grafting of 
infected material, and transm ission by phloem -feeding insect vectors. Experimentally, phytoplasmas 
can be transmitted between plants via the vascular connection formed by dodder ( Cuscuta  spp.). 
Phytoplasmas are not reported to be spread by mechanical transmission (Lee et al. 2000).  
Phloem -feeding insects in the families Cicadellidae , Cixiidae, Flatidae, Psyllidae and Aphrophoridae  
(e.g. leafhoppers, planthoppers, psyllids and spittlebugs)  are the main vectors of ‘ Ca. P. asteris’  
subgroup B  (MPI 2021). All of these families are present in New Zealand (NZOR 2021). Therefore, it 
is considered that suitable vectors for the ‘ Ca. P. asteris’ subgroup B would be present in New 
Zealand.   
The subgroups vary in the specificity of their relationships  with insect vectors; subgroup B is reported 
to have a low vector specificity (Lee et al. 1998). Insect vectors have been identified for relatively few 
phytoplasma diseases and typically when new phytoplasma diseases are discovered, little is known 
about t he disease epidemiology (Weintraub and Beanland 2006).  
Host range  
‘Candidatus  Phytoplasma  asteris’ subgroup B infects a wide range of hosts including food crops, 
trees, ornamentals and weeds (Lee et al. 2004). The wide host range of subgroup B appears to be a 
result of the large number and polyphagous nature of its insect vectors, rather than the specificity of 
the phytoplasma itself. Recorded hosts for subgroup B (from Lee et al. 2004, unless indicated) 
include, amongst others, Allium cepa  (onion), Apium graveolens  (celery), Brassica  spp., Daucus 
carota  (carrot), Hydrangea macrophylla  (hydrangea), Solanum lycopersicum  (tomato), Malus 
domestica  (apple) (Jomantiene and Davis 2005), Medicago sativa  (alfalfa), Nasturtium microphyllum  
(watercress), Olea europae a (olive), Plantago major  (broad -leaved plantain), Populus nigra  ‘Italica’ 
(Lombardy poplar), Pyrus communis  (pear), Rosa  spp. (rose) (Kamińska et al. 2006), Salix  spp. 
(willows), Solanum tuberosum  (potato), Trifolium  spp. (clover), Vitis spp. (grape) (Alm a et al. 1996), 
Zea mays  (maize), Citrus spp. (Chen et al. 2009).  
Geographic distribution  
‘Candidatus  Phytoplasma  asteris’ has been reported from all continents, except Antarctica and 
Oceania  (Table 5) .  
Table 5: Geographic distribution of ‘ Candidatus  P. asteris’  subgroup B  
Continent  Country  Reference  
Africa  Mauritius  Bellardi et al. 2018  
South Africa  Trivellone 2019  
Tunisia  Angelini et al. 2018  
Asia China  Trivellone 2019  
India  Trivellone 2019  
Iran Bellardi et al. 2018  
Japan  Trivellone 2019  
Jordan  Trivellone 2019  
Lebanon  Trivellone 2019  
Myanmar  EPPO 2020  
South Korea  Bellardi et al. 2018  
Taiwan  Trivellone 2019  
Central America and the 
Caribbean  Bermuda  EPPO 2020  
Costa Rica  EPPO 2020  
Cuba  Bellardi et al. 2018   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 30 Guatemala  EPPO 2020  
Mexico  Trivellone 2019  
St Vincent and the 
Grenadines  EPPO 2020  
Europe  Austria*  Fiore et al. 2018  
Belarus  EPPO 2020  
Belgium*  EPPO 2020  
Croatia  Trivellone 2019  
Czech Republic  Trivellone 2019; EPPO 
2020  
Denmark*  EPPO 2020  
France*  Trivellone  2019  
Germany*  EPPO 2020  
Greece*  Bellardi et al. 2018  
Hungary  EPPO 2020  
Italy*  Trivellone 2019  
Lithuania  Fiore et al. 2018  
Netherlands*  Trivellone 2019  
Poland  Kamińska et al. 2006  
Portugal*  Bellardi et al. 2018  
Romania  EPPO 2020  
Russia  Trivellone 2019; EPPO 
2020  
Serbia  Trivellone 2019  
Slovenia  Angelini et al. 2018  
Spain*  EPPO 2020  
Turkey  Fiore et al. 2018  
Ukraine  Marcone et al. 2018  
UK* Kumari et al. 2019  
North America  Canada*  Trivellone 2019  
USA* (Hawaii)  Trivellone 2019  
South America  Argentina  EPPO 2020  
Bolivia  Trivellone 2019  
Brazil  Bellardi et al. 2018  
Chile  Trivellone 2019  
Colombia  EPPO 2020  
Peru  EPPO 2020  
*indicates countries that are on the list of approved countries for the importation of Alstroemeria nursery stock  
Symptoms  
The main symptoms associated with the aster yellows group of phytoplasmas are abnormalities in 
plant growth and development. The symptoms on herbaceous hosts include leaf yellowing, stunting, 
excessive branching of auxiliary shoots ( witches’ -broom), bunching at the ends of stems, virescence 
(greening) of flowers, flower malformation, elongation of internodes, small and deformed leaves, leaf 
yellowing and phyllody (development of floral parts into leaf -like structures). In woody plants , 
symptoms are predominantly yellowing, decline, sparse foliage, and dieback (CABI 2021).  
In Alstroemeria,  ‘Ca. P. asteris’ subgroup B was isolated from plants with green and malformed 
flowers (Bertaccini et al. 1996).  
Disease latency  
‘Candidatus  Phytopla sma asteris’ has been isolated from asymptomatic roses (Kamińska et al. 2006), 
mandarin (Chen et al. 2009), ashleaf maple (Kamińska and Śliwa 2005), and asymptomatic 
grapevines in Canada (Olivier et al. 2009).  
Kamińska et al. (2006) showed that phytoplasma  infection occurs in roses that are asymptomatic of 
disease, i.e. that latent phytoplasma infection occurs. This finding applied to at least two categories of 
plants that were symptomless: 1) plants that had recovered and then showed no clear symptoms; 2)  
31 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  older plants that had no symptoms, but where the younger plants had had flower proliferation. Chen 
et al. 2009 detected ‘ Ca. P. asteris’ by PCR in asymptomatic mandarin (MPI 2016).  
 
5.1.5 Likelihood of entry:  
Phytoplasmas are transmitted from insect hosts to pl ant phloem via inoculation feeding. Once in the 
phloem, phytoplasmas multiply and spread systemically (Namba 2019). Because infection is 
systemic, phytoplasmas can be associated with all types of nursery stock, e.g. cuttings, bud wood, 
tubers, runners and bulbs. Grafting, budding, micropropagation (tissue culture) and other methods of 
vegetative propagation are efficient ways of transmitting phytoplasmas (Caglayan et al. 2019). 
Furthermore, as ‘Ca. P. asteris’ can cause asymptomatic infection of hosts (Kami ńska and Śliwa 
2005; Kamińska et al. 2006; Olivier et al. 2009),  and thus  infected mother plants may unknowingly be 
used to produce tissue culture, thereby transmitting the phytoplasma to the progeny.  
Bertaccini et al. (1996) identified phytoplasmas in mi cro-propagated shoots of Alstroemeria , 
confirming that the phytoplasma can be passed through tissue culture of this host.  
Under existing measures in the nursery stock IHS (and the commodity description), neither PEQ nor 
testing of mother plants/tissue cul ture of Alstroemeria , for phytoplasmas , is required. Given the 
possibility of asymptomatic infections, visual inspection of the commodity does not reduce the 
likelihood of entry. Therefore, if ‘ Ca. P. asteris’ subgroup B was associated with Alstroemeria tissue 
culture, there is  potential  for it to enter New Zealand.  
However, only one report was found of ‘ Ca. P. asteris’ subgroup B being associated with Alstroemeria 
plants (Bertaccini et al. 1996). It is not clear how many plants the phytoplasma was identified from, 
but it was only found in a sample of plants from the Netherlands and was not found in any of the 
plants sour ced from Italy (Bertaccini et al. 1996). No further evidence was found of Alstroemeria being 
a host of ‘ Ca. P. asteris’  subgroup B , but there are also no further examples of Alstroemeria spp. 
being tested for the phytoplasma (Google scholar  search  Alstroemeria Candidatus Phytoplasma 
asteris , search date  August 2021 ). In any case, the evidence suggests that ‘ Ca. P. asteris’ is not 
widespread in Alstroemeria plants. However, there is uncertainty because, unlike significant economic 
crops worldwide, Alstroemeria research is unlikely to be as extensive and, therefore, the extent of the 
association of ‘Ca. P. asteris’ with this host genus m ay not be fully understood.      
Given the arguments and evidence above, the likelihood of ‘Ca. P. asteris’ subgroup B entering New 
Zealand associated with Alstroemeria tissue culture is considered to be low, with high uncertainty.  
5.1.6 Likelihood of exposure:  
When a pest or pathogen arrives in a new area, it usually needs to find or encounter a growing host 
plant in order to establish. The process of a pest or pathogen encountering a growing host plant is 
termed “exposure” in MPI risk assessments and “transfer”  under the IPPC. In the case of nursery 
stock, imported plant material is maintained in a habitat favourable for plant growth, and is likely to be 
multiplied up to substantial numbers. Promoting the survival and persistence of the plant material also 
promo tes the survival and persistence of the associated pathogens.  
Given the arguments above, the likelihood of exposure of ‘ Ca. P. asteris’ subgroup B in New Zealand 
from Alstroemeria tissue culture is considered high, with low uncertainty.   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 32 5.1.7 Likelihood of esta blishment:  
‘Candidatus  Phytoplasma  asteris’ can remain systemically in the plant for as long as the plant remains 
alive. If infected plants are used for propagation of new infected plants that are planted, then the 
phytoplasma can be considered to have est ablished.  
The phytoplasma is known to occur in a range of climates, from tropical to cool temperate regions 
(Table 5). There is no evidence to suggest that establishment of ‘ Ca. P. asteris’ subgroup B is limited 
by climate. Therefore, the phytoplasma is li kely to be able to establish anywhere in New Zealand 
where suitable hosts are grown.  
Alstroemeria spp. are grown throughout New Zealand (New Zealand Plant Producers Inc 2021 pers. 
comm.). Many other reported host plants for the ‘ Ca. P. asteris’ subgroup B  phytoplasmas are 
common in New Zealand as either agricultural, horticultural or amenity species (e.g. maize, barley, 
wheat, tomato, onion, carrots, roses, pear, poplar and willow apple); weeds (e.g. plantain) or garden 
plants (e.g. hydrangea, roses, marig olds). Host plant availability is very unlikely to limit the 
establishment of ‘ Ca. P. asteris’ subgroup B in New Zealand.  
Phytoplasmas are most commonly transmitted by propagation or grafting of infected material, and by 
insect vectors (Lee et al. 2000). Alstroemeria plants that show symptoms of phytoplasma disease are 
unlikely to be propagated. However, hosts can remain asymptomatic, at least initially, meaning that 
asymptomatic plants may be propagated and distributed or shared between home gardeners, 
resulting in inadvertent spread of the phytoplasma. Distribution of infected plants throughout the 
country also increases the spread and exposure to a range of potential vectors. A species of the 
known vector genus Macrosteles, M. fieberi,  is present in New Zealand (NZOR 2021). Given the 
reported low specificity of subgroup B (Lee et al. 1998) and the incomplete knowledge of vectors, it is 
possible that other leafhoppers in New Zealand can transmit the phytoplasma. If suitable vectors are 
present, then vector  transmission is likely to be an important means of spread in New Zealand.  
Given the arguments and evidence above, the likelihood of ‘ Ca. P. asteris’ subgroup B establishing in 
New Zealand is considered moderate , with moderate uncertainty.  
5.1.8 Impacts in New Z ealand:  
Lee et al. (2004) described the typical symptoms of aster yellows (caused by members of subgroups 
16SrI -A and 16SrI -B): virescence (greening of flower petals) and phyllody (development of floral parts 
into leaf -like structures), flower streaking an d malformation, yellowing and upright posture of leaves, 
elongation of and etiolation of internodes, excessive branching of axillary shoots, witches’ -broom and 
general stunting of plants. However, some infected plants may exhibit only some of these symptom s 
and plants infected with mild strains may show no obvious symptoms. The consequences of ‘ Ca. P. 
asteris’ subgroup B in New Zealand will depend on which vectors transmit it. If there are few or no 
vectors, or if the vectors are confined to a limited range  of plants, the impacts will be minimal. If ‘ Ca. 
P. asteris’ subgroup B is transmitted by one of the widespread and common vector species with a 
wide host range, the impacts will be large. There is currently not enough  information about the 
potential vecto rs of ‘Ca. P. asteris’ subgroup B in New Zealand to determine how significant an impact 
this pathogen would have in New Zealand.  
 
a) Economic impacts  
The host range of ‘ Ca. P. asteris’ subgroup B includes  crops that are economically significant to New 
Zealand and, therefore, the pathogen has the potential to cause economic impacts by directly  
33 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  damaging horticultural crops. The host range of the pathogen includes grapes (wine export value: 
$1.8 billion Plant and Food Resear ch 2019), apples (export value: $828.8 million Plant and Food 
Research 2019), onions (domestic sales value: $30 million, export value: $170.3 million Plant and 
Food Research 2019) tomatoes (domestic sales value: $184.5 million, export value: $14.5 million 
Plant and Food Research 2019) and potatoes (export value: $129.4 million Plant and Food Research 
2019).  
Combined value of all potentially affected horticultural industries for 2018/19 is approximately $3 
billion (Plant and Food Research 2019). Even a smal l loss of yield/ marketability for all host crops 
(e.g., 1% a year for 30 years) is approximately $900 million. If economic effects are seen only on one 
or two crops, then the impact to the overall New Zealand economy will be lower, although local or 
indus try specific impacts are likely to still occur.   
The level of impacts would depend on the availability of suitable vectors in New Zealand, their host 
range and how effectively they transmit the phytoplasma.  
The impacts of phytoplasmas are uncertain becaus e symptoms are varied, and there is a tendency 
for infections to become latent and for plants to recover (Kamińska et al. 2006). However, some of the 
typical symptoms of ‘ Ca. P. asteris’ subgroup B infection affect flowers, causing virescence (greening 
of flowers), phyllody (conversion of petals and sepals to more leaf -like structures) and sterility of 
flowers (CABI 2021). These types of symptoms would have severe impacts for seed or ornamental 
crops. In 2019, the export value was $20 million for cut flower s and foliage, $42.9 million for flower 
bulbs, and $87 million for vegetable seeds (Plant and Food Research 2019).  
Given the arguments and evidence above, the potential economic impact of ‘ Ca. P. asteris’ subgroup 
B to New Zealand is considered to be low -moderate , with high uncertainty.  
 
b) Environmental  impacts  
Phytoplasmas are one of the few pathogen groups to have been associated with disease in native 
plant populations in New Zealand (Liefting et al. 2007, Phillips et al. 2008; Veerakone et al. 2015). 
‘Ca. P. asteris’ -infected leafhoppers that feed on native plants may infect those plants. Because the 
host range of ‘ Ca. P. asteris’ subgroup B appears to be largely determined by the specificity of the 
insect vectors, the native plants infected and the level  of damage that occurs will depend on which 
leafhoppers in New Zealand act as a vector and whether or not the plant is susceptible. This is difficult 
to predict , given the limited information on the ability of insects in New Zealand to transmit ‘ Ca. P. 
asteris’ subgroup B. However, given that a phytoplasma interacting with a native polyphagous vector 
produced a serious epidemic in the endemic cabbage tree ( Cordyline australis ) (Beever et al. 2004), 
there is cause for concern about possible  impacts of other phytoplasmas in native ecosystems.  
As above, the level of impacts would depend on the availability of suitable vectors in New Zealand 
and how effectively they transmit the phytoplasma.   
Given the arguments and evidence above, the likely environmental impact of ‘ Ca. P. asteris’ subgroup 
B in New Zealand is considered to be very low -moderate , with high uncertainty.  
 
c) Health  impacts  
There are no known health impacts associated with ‘ Ca. P. asteris’. As such, the health impacts of 
‘Ca. P. asteris’ subgroup B to New Zealand is considered to be negligible , with low uncertainty.   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 34 d) Social/cultural  impacts  
‘Candidatus  Phytoplasma  asteris’ subgroup B is reported to infect amenity plants such as willow and 
poplar. Other reported hosts include roses, hydrangeas, delph iniums, marigolds, tomatoes, carrots 
and potatoes which are commonly grown by home gardeners. If ‘ Ca. P. asteris’ subgroup B affects 
similar species in New Zealand, then it is expected that there will be impacts on amenity and domestic 
plantings. However, these impacts are difficult to quantify.  
The phytoplasma is also associated with leaf yellowing, severe malformation, and crinkling symptoms 
in hopbush ( Dodonaea viscosa ) – a species native to New Zealand, common in home gardens, which 
was historically use d to make weapons and garden implements by Māori.  
Given the arguments and evidence above, the social/cultural  impacts of ‘ Ca. P. asteris’ subgroup B to 
New Zealand is considered to be low, with moderate uncertainty.  
5.1.9 Management considerations  
Molecular testing using polymerase chain reaction (PCR)  
Because phytoplasma infection can be associated with asymptomatic plants, PCR techniques are the 
most reliable way to detect infection, due to their sensitivity. Several universal PCR assays have been 
developed  for the detection of all known phytoplasmas (International Plant Protection Convention 
2016) and are currently used for detection of various phytoplasmas in nursery stock by MPI (MPI 
standard 155.02.06).  
Because phytoplasmas can be unevenly distributed, a nd of uneven titre throughout plants, particularly 
in woody plants, it is best to sample symptomatic tissue to ensure detection. In a PEQ setting, 
however, it is important to detect asymptomatic infections. In asymptomatic plants, thorough sampling 
of vari ous plant tissues within a single plant is necessary to maximise the likelihood of detecting an 
infection and reduce the likelihood of false negatives (International Plant Protection Convention 2016).  
The titre of phytoplasmas in plant tissues (which can be affected by phytoplasma species, host plant 
species, timing of infection and climatic conditions)  affects the reliability of PCR testing. Because the 
location and titre of phytoplasmas within plant tissues may be affected by seasonal changes, the 
timing  of sampling is important for detection. Late summer or early autumn (or conditions simulating 
these periods) is generally regarded as the best time to test for the presence of phytoplasma s 
(International Plant Protection Convention 2016). However, some st udies have shown winter to spring 
to be the best time to sample above -ground plant parts (Garcia -Chapa et al. 2003; Kučerová et al. 
2007). It is likely that the optimal sampling season for detection varies with host species and further 
work is needed to de fine the optimal seasonal conditions for phytoplasma detection in the wide variety 
of hosts being imported.  To ensure sufficient titre, mother plants or tissue culture grown up in PEQ 
should be tested, rather than the tissue culture itself.  
The rate of fal se negative results in asymptomatic plants may be high but has not been thoroughly 
studied. A single study showed that samples of leaves from adult (n=4, 30 leaves per tree) and 
sapling (n=10, 10 leaves per sapling) Citrus aurantiifolia plants, confirmed t o be infected with  ‘Ca. P. 
aurantifolia’,  yielded negative results 38.5% and 46.25% of the time respectively. The same study 
showed that leaf samples from adult cassava ( Manihot esculenta ) plants (n=8, 10 leaves per plant), 
experimentally infected with cas sava witches’ broom phytoplasma (16SrIII -A), yielded negative results 
48.75% of the time (Donkersley et al. 2019). These rates will vary with different combinations of 
phytoplasma type, host species, timing of infection and climatic conditions. Further wor k is needed to 
define within -plant sampling protocols which will reduce the likelihood of not detecting phytoplasma 
infection if it is present.   
35 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  PCR testing can be used to detect phytoplasma infection in asymptomatic tissue and lower the 
likelihood of entry  of ‘Ca. P. asteris’ subgroup B into New Zealand to very low, which would reduce 
the overall risk to New Zealand to low. However, because of the potential for false negative results 
when sampling asymptomatic tissue, PCR testing may not lower the likelihood of entry of a 
phytoplasma to a negligible level.  
Heat treatment plus PCR testing  
Heat treatment is the oldest known method to eliminate viruses, viroids and phytoplasmas from 
vegetatively propagated plants (Zandbergen 1964 cited in Linck et al. 2019).  There is an EPPO 
standard for the control of Grapevine flavescence dorée phytoplasma in Vitis spp. (grapevine) 
propagation material (EPPO 2012). The method is also successfully used to eliminate the 
phytoplasma disease, Grassy shoot disease, from s ugarcane (Viswanathan 2001).  
In Rubus spp. Linck et al. (2019) demonstrated 100% elimination of phytoplasmas using heat 
treatment. In this study, 25 phytoplasma infected raspberry mother plants and 33 infected blackberry 
plants were heat treated over 38 d ays at 16 hours, 39°C and 8 hours at 36°C. It was noted that this 
temperature range was tolerated by Fragaria, Malus, Prunus and Rubus cultivars. Following the 
treatment, 100 raspberry and 65 blackberry plants were generated via tissue culture. All of the 
resulting plants were negative for phytoplasmas, by qPCR, following cultivation.  
This demonstrates that heat treatment of material, followed by confirmatory molecular testing, is a 
very effective method of eliminating phytoplasmas from mother plants  Howe ver, no evidence was 
found of this method being used, or trialled, to eliminate ‘ Candidatus Phytoplasma asteris’ from plant 
material (Google scholar search heat treatment ‘ Candidatus Phytoplasma asteris’, search date Sept 
2021) ; or of heat treatment being  used on Alstroemeria spp. plants (Google scholar heat treatment 
Alstroemeria plants, search date Sept 21).  
Therefore, there is the potential for the use of heat treatment followed by PCR to lower the likelihood 
of entry to New Zealand to negligible, and therefore the overall risk to New Zealand to negligible. 
However, there is moderate uncertainty due to the lack of evidence of this method currently being 
used for ‘ Ca. P. asteris’ or Alstroemeria spp.  
Assurance of Pest free area (PFA)  
A PFA officially co nfirms that the pathogen is not present in the area being considered and includes 
requirements for the use of measures to maintain freedom and to continually verify freedom. 
Therefore, it is considered that a PFA for ‘ Ca. P. asteris’  subgroup B  would reduc e the likelihood of 
entry to New Zealand to negligible. Therefore, the overall risk to New Zealand could be reduced to 
negligible.    
  
Assurance of Pest Free Place of Production (PFPP)  
As the pathogen is known to occur asymptomatically, growing season in spection may not be sufficient 
to demonstrate and maintain freedom from ‘Ca. P. asteris’  subgroup B . Other systems used in 
conjunction with observing the plants (i.e. PCR testing) would be suitable to inform a PFPP status. 
Given that tissue culture is produced indoors and usually under laboratory like conditions, it should be 
possible to prevent an incursion of ‘ Ca. P. asteris’ subgroup B into the facility. Furthermore, 
considering the extent of handling that mother Alstroemeria plants would undergo, any symptoms that 
did develop are likely to be seen. Therefore, it is considered that sourcing Alstroemer ia tissue culture  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 36 plants from a PFPP for ‘ Ca. P. asteris’  subgroup B , where the mother plants are confirmed free of the 
pathogen, would reduce the likelihood of entry to negligible. It is considered that a confirmed PFPP 
would reduce the likelihood of entr y, more than PCR testing alone, as the tests are repeated in order 
to maintain the PFPP status and the plants are produced under such controlled conditions.  
Growth in post entry quarantine (PEQ)  
Due to the potential for asymptomatic infections, growing in  PEQ and symptom observation is not 
considered a n adequate  management option for this pathogen. However, it could be used in 
combination with testing with the universal PCR primers, as used for other schedules in the nursery 
stock IHS ( MPI standard 155.02. 06). Therefore, growth in PEQ alone may not reduce the likelihood of 
entry to very low or negligible. Uncertainty would still be moderate due to the uncertainty around how 
frequently infection in Alstroemeria is asymptomatic.  
5.1.10  References  
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Alma, A; Davis, R E; Vibio, M; Danielli, A; Bosco, D; Arzone, A; Bertaccini, A (1996) Mixed infection of 
grapevines in northern Italy by phytoplasmas including 16S rRNA RFLP subgroup 16SrI -B strains 
previously unreported in this host. Plant Disease  80: 418 –421. 
 
Angelini, E; Constable, F; Duduk, B; Fiore, N; Quaglino, F; Bertaccini, A (2018) Grapevine 
phytoplasmas. In G P Rao; A Bertaccini; N Fiore; L W Liefting (eds) Phytoplasmas: Plant Pathogenic 
Bacteria - I: Characterisation and Epidemiology of Phytoplasma - Associated Diseases.  Springer 
Singapore: Singapore  
 
Beever R E; Andersen M T; Winks C J (2008) Transmission of ‘ Candidatus  Phytoplasma australiense’ 
to Cordyline australis  and Copr osma robusta.  Journal of Plant Pathology  90 (2, Supplement): S2.459.  
 
Bellardi, M G; Bertaccini, A; Madhupriya; Rao, G P (2018) Phytoplasma diseases in ornamental 
crops. In G P Rao; A Bertaccini; N Fiore; L W Liefting (eds) Phytoplasmas: Plant Pathogenic B acteria 
- I: Characterisation and Epidemiology of Phytoplasma - Associated Diseases. Springer Singapore: 
Singapore.  
 
Bertaccini, A; Vibio, M; Bellardi, M G; Danielli, A (1996) Identification of phytoplasmas in Alstroemeria. 
In IX International Symposium on  Virus Diseases of Ornamental Plants 432 : 312 –319. 
 
Bertaccini A (2007) Phytoplasmas: diversity, taxonomy, and epidemiology. Frontiers in Bioscience  12: 
673–689. 
 
Bertaccini, A; Lee, I -M (2018) Phytoplasmas: An update. In G P Rao; A Bertaccini; N Fiore; L W 
Liefting (eds) Phytoplasmas: Plant Pathogenic Bacteria - I: Characterisation and Epidemiology of 
Phytoplasma - Associated Diseases.  Springer Singapore: Singapore.  
CABI (2021) ‘Candidatus Phytoplasma asteris’ (yellow disease phytoplasma)  In: Crop Protecti on 
Compendium  https://www.cabi.org/isc/datasheet/7642 Accessed 28 June 2021  
Caglayan, K; Gazel, M; Škorić, D (2019) Transmission of phytoplasmas by agronomic practices. In A 
Bertaccini; P G Weintraub; G P Rao; N Mori (eds) Phytoplasmas: Plant Pathogenic Bacteria - II: 
Transmission and Management of Phytoplasma - Associated Diseases. Springer Singapore: 
Singapore  
Chen, J; Pu, X; Deng, X; Liu, S; Li, H; Civerolo,  E (2009) A phytoplasma related to ‘ Candidatus  
Phytoplasma asteris’ detected in citrus showing huanglongbing (yellow shoot disease) symptoms in 
Guangdong, P.R. China. Phytopathology  99: 236 –242.  
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reveal a novel and troublesome infection. In S Topolovec -Pintaric (ed) Plant Diseases: Current 
Threats and Management Trends.  IntechOpen.  
EPPO (2012) Hot water treatment of grapevine to control Grapevine flavescence  dorée 
phytoplasma.  EPPO Bulletin , 42: 490 –492. 
EPPO (2020) ‘Candidatus Phytoplasma asteris’ EPPO Global Database   
https://gd.eppo.int/taxon/PHYPAS  Accessed June 2021  
Fiore, N; Bertaccini, A; Bianco, P A;  Cieślińska, M; Ferretti, L; Hoat, T X; Quaglino, F (2018) Fruit crop 
phytoplasmas. In G P Rao; A Bertaccini; N Fiore; L W Liefting (eds) Phytoplasmas: Plant Pathogenic 
Bacteria - I: Characterisation and Epidemiology of Phytoplasma - Associated Diseases. S pringer 
Singapore: Singapore.  
Garcia -Chapa, M; Medina, V; Viruel, M A; Laviña, A; Batlle, A (2003) Seasonal detection of pear 
decline phytoplasma by nested -PCR in different pear cultivars. Plant Pathology 52(4): 513 –520. 
Gundersen, D E; Lee, I M; Rehner , S A; Davis, R E; Kingsbury, D T (1994) Phylogeny of 
mycoplasmalike organisms (phytoplasmas): a basis for their classification. The Journal of 
Bacteriology 176(17): 5244 –5254.  
International Plant Protection Convention (2016) ISPM 27 Diagnostic protocols for regulated pests DP 
12: Phytoplasmas . IPPC, FAO, Rome.  
 
IRPCM (2004) ‘ Candidatus  Phytoplasma’, a taxon for the wall -less, non -helical prokaryotes that 
colonise plant phloem and insects. International Journal of Systematic and Evolutionary Microbiology  
54: 1243 –1255.  
 
Jomantiene, R; Davis, R E (2005) Apple sessile leaf: a new disease associated with a ‘Candidatus 
Phytoplasma asteris’ subgroup 16SrI -B phytoplasma in Lithuania. Plant Pathology  54: 237.  
 
Kamińska, M; Śliwa, H (2005) Detection of ‘Candidatus  Phytoplasma asteris’ in ashleaf maple trees 
with shoot proliferation and decline. Journal of Fruit and Ornamental Plant Research  13: 123 –134. 
 
Kamińska, M; Śliwa, H; Malinowski, T (2006) Occurrence of rose degeneration symptoms in rose 
plants in Poland; p resumed phytoplasmal aetiology of rose proliferation and dieback. Acta 
Horticulturae  722: 163 –174. 
 
Kučerová, J; Karešová, R; Navratil, M; Válová, P (2007) Seasonal occurrence of ' Candidatus 
Phytoplasma pyri' in pear trees in the Czech Republic. Bulletin o f Insectology 60: 263 –264. 
 
Kumari, S; Nagendran, K; Rai, A B; Singh, B; Rao, G P; Bertaccini, A (2019) Global status of 
phytoplasma diseases in vegetable crops. Frontiers in Microbiology 10(1349).  
 
Lee I; Gundersen -Rindal D E; Bertaccini A (1998) Phytopla sma: ecology and genomic diversity. 
Phytopathology  88: 1359 –1366.  
 
Lee I M; Davis R E; Gundersen -Rindal D E (2000) Phytoplasma: phytopathogenic mollicutes. Annual 
Review of Microbiology 54: 221 –255. 
 
Lee, I M; Gundersen -Rindal, D E; Davis, R E; Bottner, K D; Marcone, C; Seemüller, E (2004) 
‘Candidatus  Phytoplasma asteris’, a novel phytoplasma taxon associated with aster yellows and 
related diseases. International Journal of Systematic and Evolutionary Microbiology  54(4): 1037 –
1048.  
 
Liefting L W; Beever R E ; Andersen M T; Clover G R G (2007) Phytoplasma diseases in New 
Zealand. Bulletin of Insectology  60(2): 165 –166. 
  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 38 Linck, H; Lankes, C; Krüger, E; Reineke, A (2019) Elimination of phytoplasmas in Rubus  mother 
plants by tissue culture coupled with heat thera py. Plant Disease , 103(6): 1252 –1255.  
 
Marcone, C; Franco -Lara, L; Toševski, I (2018) Major phytoplasma diseases of forest and urban 
trees. In G P Rao; A Bertaccini; N Fiore; L W Liefting (eds) Phytoplasmas: Plant Pathogenic Bacteria - 
I: Characterisation and Epidemiology of Phytoplasma - Associated Diseases. Springer Singapore: 
Singapore.  
 
MPI (2016) Pest Risk Assessments: Citrus spp. nursery stock. Version 1.0  
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MPI (2021) Scientific and technical advice_Phytoplasmas on nursery stock grouped PRA tables  
 
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Standard Accessed 28 June 2021  
 
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M; Masters, C; Green, M (2009) First report of aster yellow phytoplasmas (‘ Candidatus  Phytoplasma 
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Phillips, C B; Fagan, L L; Vink, C J; Brockerhoff, E G; Kean, J M; Dick, M; Stephens, A E A; Suckling, 
D M; Eve rett, K R; Hosking, G; Snell -Wakefield, A (2008) Review of nonindigenous invertebrates and 
plant pathogens in natural ecosystems.  Unpublished report to Better Border Biosecurity . 
 
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for Plant and Food Research Ltd, Auckland. https://www.freshfacts.co.nz/files/freshfacts -2019.pdf  
 
PPIN (2021) Plant pest information network. Internal MPI database Accessed June 2021  
 
Trivellone, V (2019) An online global database of Hemiptera -Phytoplasma -Plant biological 
interactions. Biodiversity Data Journal  7: e32910.  
 
Veerakone, S; Tang , J Z; Ward, L I; Liefting, L W; Perez -Egusquiza, Z; Lebas, B S M; Delmiglio, C; 
Fletcher, J D; Guy, P L (2015) A review of the plant virus, viroid, liberibacter and phytoplasma records 
for New Zealand.  Australasian Plant Pathology , 44(5): 463 –514. 
 
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shoot disease symptoms in sugarcane.  Sugar Tech , 3(3): 83 –91. 
 
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91–111. 
 
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phytoplasma differentiation, class ification and taxonomy. (Pp. 64 –92.) In: Weintraub, P G; Jones, P 
(eds.) Phytoplasmas: genomes, plant hosts and vectors. CAB International, UK.  
 
   
39 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  5.2 Clover phyllody phytoplasma  
Clover phyllody phytoplasma was originally described from Trifolium sativum (clov er) in Canada. 
Typical symptoms include the reversion of floral parts into leaf -like organs. Infected plants may also 
be stunted, chlorotic or bronzed.  
5.2.1 Taxonomic description  
Scientific name: Clover phyllody phytoplasma  
Order/Family: Acholeplasmatales/ Acholeplasmataceae  
Other names include: 16SrI subgroup C, 16SrI -C, phyllody of clover, Clover phyllody MO  
Taxonomic notes:  
Phytoplasmas form a distinct clade in the Class Mollicutes. The phytoplasma clade has been 
proposed to represent at least a genus, with each subclade (16S rRNA group) proposed to represent 
at least one species (Gundersen et al. 1994). The ‘ Candidatus  Phytoplasma asteris’ (Aster yellows) 
group (16SrI) is the largest of these groups, but it has also been divided into subgroups (A, B, C,  D, E 
and others ) Lee et al. 2004; Zhao et al. 2010.  
The species concept is defined within the phytoplasmas (IRPCM 2004), but the appropriate level at 
which to conduct a risk assessment is often unclear. Since the subgroups of the ‘ Ca. P. asteris’ 16SrI 
group phytoplasmas appear to represent distinct phylogenetic lineages, differing in distribution and 
host range, Lee et al. (2004) suggest that for quarantine purposes it would be appropriate to consider 
them separately.  
5.2.2 Summary of PRA conclusions  
The foll owing table contains a summary of risk assessment against the risk assessment criteria:  
Criteria  Rating  Uncertainty  
The likelihood of entry on the commodity, given the pathway description  Low High 
The likelihood of transferring from the imported commodity onto a suitable host  High Low 
The likelihood of establishing in the New Zealand  environment  Low Moderate  
Impacts on the New Zealand economy, environment, health and society  Low High 
Overall Level of assessed risk to New Zealand  Low Moderate  
 
Given the arguments and evidence presented : 
• Clover phyllody phytoplasma  meets the criteria to be a hazard for New Zealand  on imported 
Alstroemeria tissue culture  because it:  
o is not present in New Zealand,  
o has the potential to establish and spread in New Ze aland,  
o has the potential to cause harm to New Zealand , and  
o has been isolated from Alstroemeria sp. and has biological characteristics which 
mean it has the potential to be associated with the commodity.  
• Clover phyllody phytoplasma  poses an overall low risk on Alstroemeria tissue culture 
imported to New Zealand because it:  
o has a low likelihood of entering New Zealand on Alstroemeria tissue culture from 
India and South Africa (with moderate uncertainty) as:  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 40 - hosts infected with phytoplasmas, including the related phytoplasma ‘ Ca. P. 
asteris’, can be asymptomatic and may be used to produce tissue culture.  
- phytoplasmas systemically infect plants, and micropropagation (tissue 
culture) is a known method by which phytoplasmas are transmitted.  
- there is only one report of the phytoplasma being associated with 
Alstroemeria  sp., and therefore, does not appear to be a common host of the 
phytoplasma.   
- Clover phyllody phytoplasma is present in Indi a but is not known from South 
Africa . Therefore , the likelihood of entry on Alstroemeria tissue culture from 
South Africa  is negligible.    
o has a high likelihood of transferring  from Alstroemeria tissue culture to an appropriate 
host in New Zealand (with low uncertainty) as:  
- nursery stock is maintained in a manner favourable for plant growth, and is 
likely to be multiplied up to substantial numbers  
- promoting the survival and persistence of the plant material also promotes 
the survival and persistence of the associated pathogens.  
o has a  low likelihood of establishing in New Zealand (with moderate uncertainty) as:  
- Clover phyllody phytoplasma  can systemically infect a host plant as long as 
the plant remains alive  and,  
- it infects species that are grown in New Zealand but  are not common or 
comm ercially grown.    
- although known vectors are not present in New Zealand, insects that may be 
able to act as vectors are present.  
o may cause low overall impacts to New Zealand (with moderate uncertainty) as:  
- the host range of the phytoplasma does not include commercially significant 
crop species.  
- typical symptoms of the pathogen affect flowers, which are likely to have 
significant impacts to the cut flower, seed and ornamental industries.  
- phytoplasmas have b een associated with diseased environmental plants in 
New Zealand, therefore there is the potential for environmental impacts.  
- the extent of impacts, and on which hosts  they may occur , depends on the 
vectors present in New Zealand, their host range and thei r ability to transmit 
the phytoplasma.  
• The following measures reduce the overall risk of Clover phyllody phytoplasma  on 
Alstroemeria tissue culture : 
o PCR testing  of mother plants , or tissue culture grown in post entry quarantine,  would 
reduce the overall risk to low with low uncertainty as , although PCR testing of 
asymptomatic plants reduces the overall risk of phytoplasmas entering on nursery 
stock, there is the potential for false negatives. Therefore, PCR testing does not 
reduc e the risk to negligible.   
o Heat treatment of mother plants, followed by PCR testing would reduce the overall 
risk to negligible with moderate uncertainty, due to the lack of Alstroemeria spp. or 
Clover phyllody phytoplasma specific data.   
o Assurance of pes t free area  would reduce the overall risk to negligible with low 
uncertainty.  
o Assurance of pest free place of production would reduce the overall risk to negligible 
with low uncertainty.    
o Growth of the plants in post entry quarantine is insufficient to r educe the overall risk 
of Clover phyllody phytoplasma  due to the potential for asymptomatic infection.     
41 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  5.2.3 Hazard identification  
• Clover phyllody phytoplasma  is not known  to be present in New Zealand:  
o Clover phyllody phytoplasma  is not listed in Veerakone et al. (2015) or PPIN (2021).  
o Clover phyllody phytoplasma  is a regulated pest (ONZPR 2021)  
• Clover phyllody phytoplasma  has the potential to establish and spread  in New Zealand:  
o Clover  phyllody phytoplasma  infects species that are commonly grown in New 
Zealand.  
o Although known vectors are not present in New Zealand, insects within a known 
vector genus are present and may be able to vector the phytoplasma.  
• Clover phyllody phytoplasma  has the potential to cause harm  in New Zealand :  
o Clover phyllody phytoplasma  has a broad host range, including species common in 
the New Zealand environment.  
o Symptoms induced by Clover phyllody phytoplasma  are likely to reduce yields of 
crops, resulting in losses.  
• Clover phyllody phytoplasma  has the potential to be associated with Alstroemeria tissue 
culture :  
o Clover phyllody phytoplasma  has been isolated from Alstroemeria plants, including 
from micro -propagated shoots (Bertaccini et al. 1996).  
o Phytoplasmas are systemic pathogens and can be a ssociated with all types of 
nursery stock.   
o Therefore, the pathogen may be associated with the host and commodity.   
Given the arguments and evidence above, Clover phyllody phytoplasma  meets the criteria to be a 
hazard on  Alstroemeria tissue culture imported to New Zealand .  
Risk assessment  
5.2.4 Biology and epidemiology of Clover phyllody phytoplasma  
Phytoplasmas are phloem -limited bacteria that lack cell walls and cannot been cultured (Lee et al. 
2000, Bertaccini 2007). They are associated with a wide ran ge of symptoms affecting all plant parts; 
typical symptoms include ‘little leaf’, abnormal root growth, overall stunting, shoot proliferation, leaf 
yellowing, flower phyllody (abnormal development of flowers into leafy structures) and virescence 
(abnormal green coloration in shoots and flowers), as well as a general decline that is sometimes fatal 
(Agrios 2005). However, it is not uncommon for them to be associated with asymptomatic plants 
(Bertaccini and Lee 2018).   
 
Transmission  
There are two main mechanisms of transmission known for phytoplasmas: propagation or grafting of 
infected material, and transmission by phloem -feeding insect vectors. Experimentally, phytoplasmas 
can be transmitted between plants via the vascular connection formed by dodder (Cuscuta  spp.). 
Phytoplasmas are not reported to be spread by mechanical transmission (Lee et al. 2000).  
Phloem -feeding insects in the families Cicadellidae , Delphacidae , Flatidae, Psyllidae and 
Aphrophoridae  (e.g. leafhoppers, planthoppers, psyllids and spittlebugs) are the main vectors of 
Clover phyllody phytoplasma . All of these families are present in New Zealand (NZOR 2021). 
Furthermore, members of the species Macrosteles  (family Cicadellidae) are known vectors of Clover 
phyllody phytoplasma (MPI 2021). Members of this genus are present in New Zealand (NZOR 2021).   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 42 Therefore, it is considered that suitable vectors for the Clover phyllody phytoplasma would be present 
in New  Zealand.  
Host range  
Recorded hosts for Clover phyllody phytoplasma  (16SrI -C) include Alstroemeria sp. (Bertaccini et al. 
1996), Anemone coronaria (poppy anemone), Celtis australis (European hackberry), Eucalyptus  sp., 
Euphorbia  pulcherrima (poninsettia),  Olea europaea (European olive) (Seem üller et al. 1998), Lilium  
martagon  (Poncarov á-Vorácková et al. 1998), Limonium  sinuatum  (Babaie et al. 2007), 
Rhododendron x  hybridum  (Přibylov á et al. 2013), Salix  babylonica  (weeping willow) (Wei et al. 2009), 
Trifol ium spp. (clover) (Staniulis et al. 2000; Lee et al. 2004; Wu et al. 2010).   
Geographic distribution  
Clover phyllody phytoplasma has a more restricted distribution than ‘Ca. P. asteris’  subgroup B  
(section 5.1.5). Most reports of the phytoplasma are from Europe  (Table 6) .  
Table 6: Geographic distribution of Clover phyllody phytoplasma  
Continent  Country  Reference  
Africa  Mauritius  Martini et al. 2018  
Sudan  CABI 2019  
Asia India  Bellardi et al. 2018  
Japan  CABI 2019  
Iran Trivellone 2019  
Europe  Belarus  CABI 2019  
Belgium*  CABI 2019  
Bulgaria  CABI 2019  
France*  Trivellone 2019  
Germany*  Trivellone 2019  
Hungary  Trivellone 2019  
Ireland  CABI 2019  
Italy*  Trivellone 2019  
Lithuania  Trivellone 2019  
Poland  Martini et al. 2018  
Portugal*  CABI 2019  
Romania  CABI 2019  
Russia  Trivellone 2019  
Serbia  Trivellone 2019  
Switzerland  CABI 2019  
UK* Trivellone 2019  
North America  Canada*  Trivellone 2019  
USA* (Florida)  Trivellone 2019  
Oceania  Australia  CABI 2019  
*indicates countries that are on the list of approved countries for the importation of Alstroemeria nursery stock  
Symptoms  
In Trifolium spp. (clover) characteristic symptom of Clover phyllody phytoplasma infection is the 
reversion of floral parts into leaf -like organs (phyllody). Plants may also be stunted, chlorotic or 
bronzed. Root nodulation may be reduced,  and no seed is produced (CABI 2019; PNWhanbooks 
undated).   
 
 
Disease latency   
43 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  No evidence was found of Clover phyllody phytoplasma being associated wi th asymptomatic host 
plants (Google and Google Scholar search: Clover phyllody phytoplasma asymptomatic). However, it 
is not uncommon for phytoplasmas to be associated with asymptomatic plants (Bertaccini and Lee 
2018). For example, Kamińska et al. (2006) showed that phytoplasma infection occurs in roses that 
are asymptomatic of disease, i.e., that latent phytoplasma infection occurs. This finding applied to at 
least two categories of plants that were symptomless: 1) plants that had recovered and then showe d 
no clear symptoms; 2) older plants that had no symptoms, but where the younger plants had had 
flower proliferation. Chen et al. 2009 detected ‘ Ca. P. asteris’ by PCR in asymptomatic mandarin 
leaves  (MPI 2016).   
 
5.2.5 Likelihood of entry:  
Clover phyllody phyto plasma was isolated from Alstroemeria sp. by Bertaccini et al. (1996), in the 
same study that ‘Ca. P. asteris’ subgroup B was isolated from th is host. Based on the data presented, 
the arguments for the likelihood of entry for clover phyllody phytoplasma is considered the same as 
for ‘Ca. P. asteris’  subgroup B . However, unlike ‘ Ca. P. asteris’  subgroup B , Clover phyllody 
phytoplasma is reported fr om India, but not South Africa.  
Phytoplasmas are transmitted from insect hosts to plant phloem via inoculation feeding. Once in the 
phloem, phytoplasmas multiply and spread systemically (Namba 2019). Because infection is 
systemic, phytoplasmas can be asso ciated with all types of nursery stock, e.g. cuttings, bud wood, 
tubers, runners and bulbs. Grafting, budding, micropropagation (tissue culture) and other methods of 
vegetative propagation are efficient ways of transmitting phytoplasmas (Caglayan et al. 20 19). 
Furthermore, as other phytoplasmas, including the closely related ‘Ca. P. asteris’, can cause 
asymptomatic infection of hosts (Kamińska and Śliwa 2005; Kamińska et al. 2006; Olivier et al. 2009), 
infected mother plants may unknowingly be used to produ ce tissue culture, thereby transmitting the 
phytoplasma to the progeny.  
Bertaccini et al. (1996) identified phytoplasmas in micro -propagated shoots of Alstroemeria , 
confirming that the phytoplasma can be passed through tissue culture of this host (Bertacc ini et al. 
1996).  
Under existing measures in the nursery stock IHS (and the commodity description), neither PEQ nor 
testing of mother plants/tissue culture of Alstroemeria for phytoplasmas is required. Given the 
possibility of asymptomatic infections, vis ual inspection of the commodity does not reduce the 
likelihood of entry. Therefore, if the Clover phyllody phytoplasma was associated with Alstroemeria 
tissue culture, it is likely to enter New Zealand.  
However, only one report was found of Clover phyllod y phytoplasma being associated with 
Alstroemeria plants (Bertaccini et al. 1996). It is not clear how many plants the phytoplasma was 
identified from, but it was only found in a sample of plants from the Netherlands and was not found in 
any of the plants s oured from Italy (Bertaccini et al. 1996). No further evidence was found of 
Alstroemeria being a host of Clover phyllody phytoplasma, but there are also no further examples of 
Alstroemeria spp. being tested for the phytoplasma (Google scholar  search  Alstro emeria Clover 
phyllody phytoplasma  search date August 2021 ). In any case, the evidence suggests that Clover 
phyllody phytoplasma is not widespread in Alstroemeria plants. However, there is uncertainty 
because, unlike significant economic crops worldwide, Alstroemeria research is unlikely to be as 
extensive and, therefore, the extent of the association of Clover phyllody phytoplasma with this host 
genus may not be fully understood.       
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 44 Given the arguments and evidence presented, the likelihood of Clover phy llody phytoplasma entering 
New Zealand associated with Alstroemeria tissue culture, from countries where the pathogen is 
known to occur, is considered to be low with high uncertainty.  
5.2.6 Likelihood of exposure:  
When a pest or pathogen arrives in a new area, it usually needs to find or encounter a growing host 
plant in order to establish. The process of a pest or pathogen encountering a growing host plant is 
termed “exposure” in MPI risk assessments and “transfer” under the IPPC. In the case of nursery 
stock, imported plant material is maintained in a habitat favourable for plant growth, and is likely to be 
multiplied up to substantial numbers. Promoting the survival and persistence of the plant material also 
promotes the survival and persistence of the associa ted pathogens.  
Given the arguments above, the likelihood of exposure of Clover phyllody phytoplasma in New 
Zealand from Alstroemeria tissue culture is considered high, with low uncertainty.  
5.2.7 Likelihood of establishment:  
Clover phyllody phytoplasma can remain systemically in the plant for as long as the plant remains 
alive. If infected plants are used for propagation of new infected plants that are planted, then the 
phytoplasma can be considered to have established.  
The phytoplasma is predominantly repor ted from cool temperate regions with a similar climate to New 
Zealand (Table 6). There is no evidence to suggest that establishment of the Clover phyllody 
phytoplasma is determined by climate. Therefore, the phytoplasma is likely to be able to establish 
anywhere in New Zealand where suitable hosts are grown.  
Alstroemeria spp. are grown throughout New Zealand (NZPPI 2021 pers. comms.). The breadth of 
host plants of the phytoplasma is more limited compared to ‘ Ca. P. asteris’  subgroup B , however 
reported hos ts do include plants that are present in New Zealand, such as Salix babylonica (weeping 
willow), Rhododendron x hybridum  and Olea europaea (European olive) (Wei et al. 2009; P řibylov á et 
al. 2013; Seem üller et al. 1998). However, these are not common comme rcial species and therefore, 
are unlikely to be as abundant as the commercial crops that are hosts of ‘ Ca. P. asteris’. Therefore, 
establishment of Clover phyllody phytoplasma may be limited by host plant availability.  
Phytoplasmas are most commonly trans mitted by propagation or grafting of infected material, and by 
insect vectors (Lee et al. 2000). Alstroemeria plants that show symptoms of phytoplasma disease are 
unlikely to be propagated. However, hosts can remain asymptomatic, at least initially, meanin g that 
asymptomatic plants may be propagated and distributed or shared between home gardeners, 
resulting in inadvertent spread of the phytoplasma. Distribution of infected plants throughout the 
country also increases the spread and exposure to a range of p otential vectors. A species of the 
known vector genus Macrosteles, M. fieberi,  is present in New Zealand (NZOR 2021). If suitable 
vectors are present, then vector transmission is likely to be an important means of spread in New 
Zealand.  
Given the restricte d host range compared to ‘Ca. P. asteris ’ subgroup B , the likelihood of 
establishment for Clover phyllody phytoplasma is considered to be lower than the likelihood of ‘Ca. P. 
asteris ’ subgroup B establishing , which  was rated as moderate.  
Given the arguments and evidence above, the likelihood of Clover phyllody phytoplasma establishing 
in New Zealand is considered low-moderate , with moderate uncertainty.  
  
45 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  5.2.8 Impacts in New Zealand:  
 
a) Economic impacts  
Poncarov á-Vorácková et al. 1998 identified C lover phyllody phytoplasma from Lilium martagon plants 
with flattened stems. Lilium spp. are exported from New Zealand as bulbs , with an export value of 
$24.4 million in 2019 (Plant & Food Research 2019). Impacts may be seen both through yield 
reduction an d through increase phytosanitary measures that exporters need to meet.  
The phytoplasma is also reported from Eucalyptus sp., which is a commercial forestry species in New 
Zealand, with 21,777 ha planted (FOA 2019/2020). The main symptoms reported from thi s host are 
unlikely to cause significant i mpacts  for timber production, although smaller leaves may reduce tree 
growth via reduced photosynthetic ability ( Rao et al. 2018 ).  
Clover, which is an important feed crop for the dairy industry , is a recorded host  of the phytoplasma . 
Therefore, there is also the potential for this pathogen to negatively impact the dairy industry (milk and 
cream export value $10 billion). However, it is very difficult to quantify what level of crop loss may be 
caused by Clover phyllody phytoplasma infection, and what reduction in milk yield this may have.   
The full extent of impacts that may be caused to New Zealand  by Clover phyllody phytoplasma , 
depends on the number of suitable vectors in New Zealand and the ir ability to transmit the 
phytoplasma. If there are few vectors, or they do not successfully transmit the phytoplasma, the 
impacts are likely to be much lower. Furthermore, the host range of the phytoplasma in New Zealand 
would be determined by the host r ange of the available vectors. The impacts of phytoplasmas are 
uncertain because symptoms are varied, and there is a tendency for infections to become latent and 
for plants to recover (Kamińska et al. 2006).  
Given the arguments and evidence above, the econ omic impact of Clover phyllody phytoplasma to 
New Zealand is considered to be low, with moderate uncertainty.  
 
b) Environmental impacts  
Phytoplasmas are one of the few pathogen groups in New Zealand to have been associated with 
disease in native plant populat ions (Liefting et al. 2007, Phillips et al. 2008; Veerakone et al. 2015). 
Clover phyllody phytoplasma -infected leafhoppers that feed on native plants may infect those plants. 
Because the host range of phytoplasmas appears to be largely determined by the sp ecificity of the 
insect vectors, the native plants that may be infected and the level of damage that could occur will 
depend on which leafhoppers in New Zealand act as a vector and whether or not the plant is 
susceptible. This is difficult to predict given  the limited information on the ability of insects in New 
Zealand to transmit exotic phytoplasmas. However, given that a phytoplasma interacting with a native 
polyphagous vector produced a serious epidemic in the endemic cabbage tree ( Cordyline australis ) 
(Beever et al. 2004), there is cause for concern about the impacts of other phytoplasmas in native 
ecosystems.  
As with economic impacts,  the level of environmental impacts would depend on the availability of 
suitable vectors in New Zealand and how effectiv ely they transmit the phytoplasma.   
Given the arguments and evidence above, the environmental impacts of Clover phyllody phytoplasma  
in New Zealand is considered to be very low -moderate , with high uncertainty.  
 
  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 46 c) Health impacts  
There are no known health impacts associated with Clover phyllody phytoplasma . As such, the health 
impacts of Clover phyllody phytoplasma  to New Zealand is considered to be negligible , with low 
uncertainty.  
 
d) Social/cultural impacts  
Clover phyllody phytoplasma  is reported to infect the amenity plants Eucalyptus spp. and Salix sp. 
(willow) , and other reported hosts are grown as ornamentals by home gardeners. However, these 
species do not have a particular social or cultural significance.   
Given the a rguments and evidence above, the social/cultural  impacts of Clover phyllody phytoplasma  
to New Zealand is considered to be very low , with moderate uncertainty.  
5.2.9 Management considerations  
Molecular testing using polymerase chain reaction (PCR)  
Because phytop lasma infection can be associated with asymptomatic plants, PCR techniques are the 
most reliable way to detect infection, due to their sensitivity. Several universal PCR assays have been 
developed for the detection of all known phytoplasmas (International Plant Protection Convention 
2016) and are currently used for detection of various phytoplasmas in nursery stock by MPI (MPI 
standard 155.02.06).  
Because phytoplasmas can be unevenly distributed, and of uneven titre throughout plants, particularly 
in woody plants, it is best to sample symptomatic tissue to ensure detection. In a PEQ setting, 
however, it is important to detect asymptomatic infections. In asymptomatic plants, thorough sampling 
of various plant tissues within a single plant is necessary to maxi mise the likelihood of detecting an 
infection if it is present and reduce the likelihood of false negatives (International Plant Protection 
Convention 2016).  
The titre of phytoplasmas in plant tissues (which can be affected by phytoplasma species, host pl ant 
species, timing of infection and climatic conditions)  affects the reliability of PCR testing. Because the 
location and titre of phytoplasmas within plant tissues may be affected by seasonal changes, the 
timing of sampling is important for detection. La te summer or early autumn (or conditions simulating 
these periods) is generally regarded as the best time to test for the presence of phytoplasma 
(International Plant Protection Convention 2016). However, some studies have shown winter to spring 
to be the best time to sample above -ground plant parts (Garcia -Chapa et al. 2003; Kučerová et al. 
2007). It is likely that the optimal sampling season for detection varies with host species and further 
work is needed to define the optimal seasonal conditions for phy toplasma detection in the wide variety 
of hosts being imported.  To ensure sufficient titre, mother plants or tissue culture grown up in PEQ 
should be tested, rather than the tissue culture itself.  
The rate of false negative results in asymptomatic plants may be high but has not been thoroughly 
studied. A single study showed that samples of leaves from adult (n=4, 30 leaves per tree) and 
sapling (n=10, 10 leaves per sapling) Citrus aurantiifolia plants, confirmed to be infected with  ‘Ca. P. 
aurantifolia’,  yielded negative results 38.5% and 46.25% of the time respectively. The same study 
showed that leaf samples from adult cassava ( Manihot esculenta ) plants (n=8, 10 leaves per plant), 
experimentally in fected with cassava witches’ broom phytoplasma (16SrIII -A), yielded negative results 
48.75% of the time (Donkersley et al. 2019). These rates will vary with different combinations of 
phytoplasma type, host species, timing of infection and climatic conditio ns. Further work is needed to  
47 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  define within -plant sampling protocols which will reduce the likelihood of not detecting phytoplasma 
infection if it is present.  
PCR testing can be used to detect phytoplasma infection in asymptomatic tissue and lower the 
likelihood of entry of Clover phyllody phytoplasma into New Zealand to very low, which would reduce 
the overall risk to New Zealand to low. However, because of the potential for false negative results 
when sampling asymptomatic tissue, PCR testing may not lowe r the likelihood of entry of a 
phytoplasma to a negligible level.  
Heat treatment plus PCR testing  
Heat treatment is the oldest known method to eliminate viruses, viroids and phytoplasmas from 
vegetatively propagated plants (Zandbergen 1964 cited in Linck e t al. 2019).  There is an EPPO 
standard for the control of Grapevine flavescence dorée phytoplasma in Vitis spp. (grapevine) 
propagation material (EPPO 2012). The method is also successfully used to eliminate the 
phytoplasma disease, Grassy shoot disease, from sugarcane (Viswanathan 2001).  
In Rubus spp. Linck et al. (2019) demonstrated 100% elimination of phytoplasmas using heat 
treatment. In this study, 25 phytoplasma infected raspberry mother plants and 33 infected blackberry 
plants were heat treated ove r 38 days at 16 hours, 39°C and 8 hours at 36°C. It was noted that this 
temperature range was tolerated by Fragaria, Malus, Prunus and Rubus cultivars. Following the 
treatment, 100 raspberry and 65 blackberry plants were generated via tissue culture. All o f the 
resulting plants were negative for phytoplasmas, by qPCR, following cultivation.  
This demonstrates that heat treatment of material, followed by confirmatory molecular testing, is a 
very effective method of eliminating phytoplasmas from mother plants   However, no evidence was 
found of this method being used, or trialled, to eliminate Clover phyllody phytoplasma (Google scholar 
search: heat treatment clover phyllody phytoplasma, search date Sept 21) from plant material; or of 
heat treatment being used on Alstroemeria spp. plants (Google scholar search: heat treatment 
Alstroemeria plants, search date Sept 21).  
Therefore, there is the potential for the use of heat treatment followed by PCR to lower the likelihood 
of entry to New Zealand to negligible, an d therefore the overall risk to New Zealand to negligible. 
However, there is moderate uncertainty due to the lack of evidence of this method currently being 
used for Clover phyllody phytoplasma or Alstroemeria spp. 
Assurance of Pest free area (PFA)  
A PFA officially confirms that the pathogen is not present in the area being considered and includes 
requirements for the use of measures to maintain freedom and to continually verify freedom. 
Therefore, it is considered that a PFA for Clover phyllody phyt oplasma would reduce the likelihood of 
entry to New Zealand to negligible. Therefore, the overall risk to New Zealand could be reduced to 
negligible.    
  
Assurance of Pest Free Place of Production (PFPP)  
Although no evidence was found of Clover phyllody phytoplasma being associated with asymptomatic 
host plants, other phytoplasmas, including the closely related ‘ Ca. P. asteris’ subgroup B is known to 
cause asymptomatic infection s (Kamińska and Śliwa 2005; Kamińska et al. 2006; Olivier et al. 2009 ). 
Furthe rmore, there is limited literature regarding the nature of Clover phyllody phytoplasma infection.  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 48 Therefore, there is the potential for this phytoplasma to infects hosts without causing symptoms. This 
means that growing season inspection may not be suffici ent to demonstrate and maintain freedom of 
Clover phyllody phytoplasma. Other systems used in conjunction with observing the plants (i.e. PCR 
testing) would be suitable to inform a PFPP status. Given that tissue culture is produced indoors and 
usually unde r laboratory like conditions, it should be possible to prevent an incursion of the Clover  
phyllody phytoplasma.  Furthermore, considering the extent of handling that mother Alstroemeria 
plants would undergo, any symptoms that did develop are likely to be se en. Therefore, it is 
considered that sourcing Alstroemeria tissue culture plants from a PFPP for Clover phyllody 
phytoplasma , where the mother plants are confirmed free of the pathogen, would reduce the 
likelihood of entry to negligible. It is considered t hat a confirmed PFPP would reduce the likelihood of 
entry, more than PCR testing alone, as the tests are repeated in order to maintain the PFPP status 
and the plants are produced under such controlled conditions.  
Growth in post entry quarantine (PEQ)  
Due to the potential for asymptomatic infections  of phytoplasmas , growing in PEQ and symptom 
observation is not considered a n adequate management option for this pathogen. However, it could 
be used in combination with testing with the universal PCR primers, as  used for other schedules in 
the nursery stock IHS ( MPI standard 155.02.06). Therefore, growth in PEQ alone may not reduce the 
likelihood of entry to very low or negligible. Uncertainty would still be moderate due to the uncertainty 
around how frequently i nfection in Alstroemeria is asymptomatic.  
 
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51 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Zhao, Y; Wei, W; Davis, R E; Lee, I M (2010) Chapter 5. Recent advances in 16S rRNA genebased 
phytoplasma differentiation, classification and taxonomy. (Pp. 64 –92.) In: Weintraub, P G; Jones, P 
(eds.)  Phytoplasmas: genomes, plant hosts and vectors. CAB International, UK.  
   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 52 6. Pest risk assessments: Viruses  
6.1 Broad bean wilt virus 2  
The virus species  Broad bean wilt virus  2 (BBWV -2) has a widespread distribution and broad host 
range, infecting hosts in at least 24 plant families. It has been reported naturally infecting 
Alstroemeria , causing symptoms of dwarfing, necrosis, and mosaic (Fuji et al. 2007) .  
6.1.1 Taxonomic description  
Scientific name: Broad bean wilt virus 2  (BBWV -2) Genus: Fabavirus (ICTV 2021)  
Order/Family: Picornavirales: Secoviridae  
Othe r names include: Broad bean wilt virus  serotype II,  plantago II virus,  Patchouli mild mosaic 
virus , Petunia ringspot virus . 
Taxonomic notes:  broad bean wilt viruses were originally considered one species divided into two 
serotypes (I and II), but are now c lassified as two distinct species within the genus Fabavirus ; Broad 
bean wilt virus 1  (BBWV -1) and Broad bean wilt virus 2  (BBWV -2) (Kobayashi et al. 1999) . 
Patchouli mild mosaic virus  (PatMMV) has high sequence identity with BBWV -2 (81 -97%), so likely 
represents a strain of BBWV -2 (Ikegami et al. 2001) . Petunia ringspot virus  is cited as a synonym of 
BBWV -2 in some literature (Virus Taxonomy 2012) , but as BBWV -1 in other sources (Lisa and 
Boccardo 1996; Sastry e t al. 2019) .  
6.1.2 Summary of IRA conclusions  
The following table contains a summary of risk assessment against the risk assessment criteria : 
Criteria  Rating Uncertainty  
The likelihood  of entry on the commodity, given the commodity description  Very low  High 
The likelihood of transferring  from the imported commodity onto a suitable host  High Low 
Suitability of establishing in the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Low Low 
Overall Level of assessed risk to New Zealand  Low Low 
 
Given the arguments and evidence presented : 
• BBWV -2 meets the criteria to be a hazard for New Zealand  because  it (and its strains) : 
o is not present in New Zealand,  
o has the potential to  establish and spread in  New Zealand ,  
o has the potential  to cause harm to New Zealand , and  
o has been isolated from Alstroemeria sp. and has biological characteristics that mean 
it has the potential to be associated with tissue culture . 
• BBWV -2 poses a n overall  moderate  risk on  Alstroemeria tissue culture  imported to New 
Zealand because  it: 
o has a very low likelihood  of entering New Zealand on Alstroemeria tissue culture from 
South Africa and India  (with high uncertainty) as:  
- the virus has not been widely reported infecting Alstroemeria ,  
53 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  - there appears to be a low prevalence of the virus in South Africa , 
- the virus is not reported to be present in India . 
- while only symptomatic infection ha s been reported in Alstroemeria , 
symptoms  are variable  and may not be observable  on tissue  culture . 
o has a high likelihood  of transferring  from Alstroemeria tissue culture  to an appropriate 
host in New Zealand  (with low uncertainty) as:  
- Alstroemeria  tissue culture will be held in a favourable environment for plant 
growth, thereby promoting the proliferation of the virus.  
- the virus is transmitted by aphids in a non -persistent manner (vector will 
retain the virus for several minutes up to a few hours),  which would result in 
the transmission of the virus from the initial source to new hosts in a nursery 
setting.  
o has a high likelihood  of establishing in New Zealand  (with low uncertainty) as:  
- the virus has a widespread distribution which suggests that ther e would be no 
climatic barriers preventing establishment.  
- the virus naturally infects a wide range of plants in at least 24 plant families  
(which contain species present in New Zealand) , so hosts will be widely 
available for the virus to establish.  
- the vir us can be transmitted by aphid vectors that are present in New 
Zealand.  
- the virus can also be transmitted by mechanical inoculation and may be 
spread by grafting and the movement of infected propagative material.  
- there is a very low but non -negligible risk  of seed transmission.  
- infection of weedy plant species and perennial plants that can act as 
reservoirs for the virus will provide an ongoing source of inoculum.  
o may cause moderate  overall impacts on New Zealand  (with moderate  uncertainty) as:  
- the virus i s reported to infect several vegetable crops of economic importance 
to New Zealand including tomatoes, peppers, spinach, beans, and peas, and 
outbreaks of the virus can be expected to cause a significant reduction in the 
economic value of these crops.  
- this virus infects numerous ornamental species commonly grown in private 
gardens and the symptoms of the virus will reduce the aesthetic value of 
these plants.  
- given the broad host range of BBWV -2, it may infect native New Zealand 
species, resulting in environ mental, social, and cultural impacts.  
• The following measures reduce the overall risk of BBWV -2 on Alstroemeria  tissue culture : 
o A Pest Free Area would reduce the likelihood of entry to negligible, thereby reducing 
the overall risk to negligible with low uncertainty.  
o A Pest Free Place of Production would reduce the likelihood of entry to negligible, 
thereby reducing the overall risk to negligible with low uncertainty.  
o Pre-determined testing of Alstroemeria  mother plants, or tissue culture grown up in 
post entry quarantine, using PCR or ELISA techniques would reduce the likelihood of 
entry to negligible, thereby reducing the overall risk to negligible with low uncertainty.  
6.1.3 Hazard identification  
• BBWV -2 is not known  to be present in New Zealand:  
o BBWV -2 is not listed in Veerakone et al. (2015) or PPIN (2021).   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 54 o BBWV -2 is a regulated pest (ONZPR 2021)  
• BBWV -2 has the potential to establish and spread  in New Zealand:  
o The virus is widely distributed  across all continents (except Ant arctica) in areas of 
varyin g climate types , therefore there is unlikely to be any climatic barrier to prevent 
its establishment and spread.  
o The virus has a broad host range and infects many common horticultural and 
ornamental species in New Zealand (Ferrer et al. 2011) . It can also infect weedy 
species present in New Zealand that may act as a reservoir or means of spread for 
the disease (Gracia and Feldman 1976) . 
o The virus is transmitted by aphid vectors that are present in New Zealand (Dunich 
and Mishchenko 2015; NZOR 2021) . 
o The virus can be transmitted through mech anical mechanisms so may be spread by 
common agricultural practices such as pruning, grafting and the movement of 
propagative material (Dunich and Mishchenko 2015) . 
o The virus may also be seed trans mitted at very low frequencies, which may aid in its 
field establis hment (Putz and Kuszala 1973).  
• BBWV -2 has the potential to cause harm  in New Zealand:  
o The virus has a broad host range, with natural infection reported in at least 4 8 host 
plants across 24 plant families. The virus is known to infect many horticultural a nd 
ornamental crops of significance to New Zealand (Ferrer et al. 2011; He et al. 2021) , 
so can be expected to have economic impacts.  
o Symptoms induced by BBWV -2 are likely to reduce yields of crops, resulting in 
losses.  Infections of horticultural and ornamental species may have social and 
cultural impacts.  
o The broad host range of this virus suggests that it may be able to infect native 
species, which can be expected to have environmental, social, and cultural impacts.  
• BBWV -2 has the potential to b e associated with Alstroemeria tissue culture :  
o BBWV -2 has been isolated from Alstroemeria ligtu plants (Fuji et al. 2007).  
o BBWV -2 causes systemic infection in Alstroemeria  and many other species  (Fuji et 
al. 2007) , so may be associated with all types of nursery stock.   
o Therefore, the pathogen may be associated with the host and commodity.   
Given the arguments and evidence above, BBWV -2 meets the criteria to be a hazard  on Alstroemeria 
tissue culture imported to tissue culture imported to New Zealand.  
Risk assessment  
6.1.4 Biology and epidemiology of Broad bean wilt virus  2 
Hosts  
A review of the literature found natural infections of BBWV -2 in at least 48 different plant species from 
41 genera and 24 families  (Table  7). There are many other reports of hosts in other plant families 
infected with broad bean wilt virus  where the plant species or virus serotype is not identified, including 
Begoniaceae, Bignoniaceae, Iridaceae, Plumbaginaceae, Amaryllidacea e, and Vitaceae (Sastry et al. 
2019) . Experimental infections were reported in at least 10 other plant genera and 2 further plant 
families (Aizoaceae and Chenopodaceae) (Fuji et al. 2007; Wei and Li 2017; Uehara -Ichiki et al. 
2020) .  
Significant horticultural hosts include beets, eggplant, celery, pepper, tomato, spinach, broad bean, 
pea, field mustard and lettuce. Ornamental hosts include alstroemeria, p urple coneflower, gladiolus, 
Japanese gentian, lily, patchouli, buttercup, sage, marigold and nasturtium. Weedy species known to 
host BBWV -2 may act as a reservoir for the virus, such as periwinkle, foxglove, ribwort plantain and 
London rocket 
55 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Table  7: Hos t families and species susceptible to  broad  bean wilt virus 2 . Blank cells mean no data was available regarding symptoms.  
 
Family  Species (common name)  Symptoms  Natural 
infections 
reported? 
(Y/N)  Reference  
Acanthaceae  Megaskepasma  erythrochlamy  
(Brazilian red cloak)  Mosaic, leaf distortion  
Y Koh et al. (2001); Ferre r et al. (2011)  
Aizoaceae  Tetragonia  tetragonoides  (New 
Zealand spinach)  Chlorotic spots on inoculated leaves  
N Fuji et al. (2007 ) 
Alstroemeriaceae  Alstroemeria  ligtu (Peruvian lily)  Dwarfing, necrosis, mosaic  Y Fuji et al. (2007)  
Amaranthaceae  Achyranthes  bidentata  Mosaic, yellowing  Y Seo et al. (2014); Kwon and Seo (2019)  
 A. japonica  (oriental chaff flower)   
Y Ferrer et al. (2011); Kwon and Seo 
(2019)  
 Beta vulgaris  (beet)  Chlorotic spots, mottling  N Fuji et al. (2007)  
 Gomphrena  globosa  (globe 
amaranth)  Mild mosaic, leaf malformation, 
purple spots on inoculated leaves  N Fuji et al. (2007)  
 Spinacia  oleracea  (spinach)   Y Ferrer et al. (201 1); Kwak et al. (2013)  
Apiaceae  Apium  graveolens  (celery)   Y Kwak et al. (2013)  
 Buplerum  chinense   Y Sui et al. (2009)  
Apocynaceae  Catharanthus  roseus  (periwinkle)  Asymptomatic  Y Shukla et al. (1980)  
Asteraceae  Atractylodes  macrocephala  Mosaic, yellowing  Y Niu et al. (2015)  
 Echinacea  purpurea  (purple 
coneflower)  Necrosis, leaf curling, yellow mosaic  
Y Li et al. (2012); Dunich and Mishchenko 
(2015)  
 Gynura  japonica  Chlorotic spots, mosaic  Y Lai et al. (2021)  
 G. procumbens  (longevity spinach)  Chlorotic lesions, vein chlorosis, 
mosaic, mottling, stunting  Y Kwak et al. (2017)  
 Lactuca  indica  (Indian lettuc e) Mottling  Y Wu et al. (2010)  
 L. sativa  (lettuce)   Y Uyemoto and Provvidenti (1974)  
 Tagetes  erecta  (Marigold)  Mosaic  Y Yongqiang et al. (2021)  
 Zinnia  elegans  (common zinnia)  Asymp tomatic  N Fuji et al. (2007)  
Basellaceae  Ullucus  tuberosus  (ulluco)   Y Fox et al. (2019)  
Brassicaceae  Brassica  rapa (field mustard)  Mottling  Y Cai et al. (2017)  
 Sisymbrium  irio (London rocket)  Leaf distortion  Y Gracia and Feldman (1976)  
Caryophyllaceae  Pseudostellaria  heterophylla  (false 
starwort)   
Y Ye et al. (2015)  
Chenopodiaceae  Chenopodium  amaranticolor  Chlorosis, chlorotic spots, 
malformation, apical necrosis  N Fuji et al. (2007); Wei and Li (2017)   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 56 Family  Species (common name)  Symptoms  Natural 
infections 
reported? 
(Y/N)  Reference  
 C. quinoa  (quinoa)  Chlorosis, chlorotic spots, 
malformation, apical necrosis  N Fuji et al. (2007); Wei and Li (2017)  
Cornaceae  Cornus florida (flowering dogwood)  Yellow mosaic  Y Scott and Barnett (1984)  
Dioscoreaceae  Dioscorea  oppositifolia  (Chinese 
yam)  Mosaic, stunting, mottling, 
yellowing, leaf distortion  Y Kwon  et al. (2016)  
Fabaceae  Glycine  max (soybean)  Asymptomatic  N Fuji et al. (2007)  
 Phaseolus  vulgaris  (common bean)  Asymptomatic  N Fuji et al. (2007)  
 Pisum sativum  (pea)  Mosaic, vein clearing  Y Jooste et al. (2001)  
 Vicia  faba (broad bean)  Leaflet necrosis, wilting, mosaic, 
chlorotic spots, ringspot, mottling, 
distortion, apical necrosis, death  Y Kwak et al. (2013); Wei and Li (2017)  
 Vigna  unguiculata  (cowpea)  Chlorotic spots, vein clearing, 
mosaic  N Fuji et al. (2007); Wei and Li (2017)  
Gentianaceae  Eustoma  russellianum  (Texas 
bluebell)  Chlorotic spots, necrotic spots  
Y Shen et al. (2012)  
 Gentiana  scabra  (Japanese 
gentian)  Stunting, necrosis  
Y Verhoeven et al. (2002)  
 G. trifloral   Y Verhoeven et al. (2002)  
Iridaceae  Gladiolus  hybridus  (gladiolus)   Y Kwak et al. (2013)  
Lamiaceae  Leonurus  sibiricus  (honeyweed)  Mosaic, yellowing, stunting  Y Seo et al. (2014)  
 Perilla  frutescans  (perilla)  Mosaic, leaf curling  Y Xia et al. (2020)  
 Pogoste mon cablin  (patchouli)  Mosaic  
Y Ferrer et al. (2011); Miftakhurohmah et 
al. (2015)  
 Salvia  officinalis  (common sage)  Leaf curling, distortion  
Y Mumford et al. (2006); Fowkes et al. 
(2017)  
Liliaceae  Lilium  sp. (Lily)   Y Kwak et al. (2013)  
Orobanchaceae  Rehmannia  glutinosa   Y Kwak et al. (2018)  
Pedaliaceae  Sesamum  indicum  (sesame)  Mosaic, chlorotic mottling, distortion, 
puckering, asymptomatic  infection 
after experimental inoculation  Y Fuji et al. (2007); Wang et al. (2017)  
Plantaginaceae  Digitalis  lanata  (foxglove)  Mottling  Y Dong et al. (2017); Fowkes et al. (2017)  
 Plantago  lanceolata  (plantain)  Mosaic, mottling, chlorotic rings  Y Gracia and Feldman (1976)  
 Veronica  gentianoides  (gentian 
speedwell)  Distortion, mottling  
Y Fowkes et al. (2017)   
57 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Family  Species (common name)  Symptoms  Natural 
infections 
reported? 
(Y/N)  Reference  
Ranunculaceae  Helleborus vesicarius  Ringspots  Y Sastry et al. (2019)  
 Ranunculus  asiaticus  (buttercup)  Leaf deformation, mosaic  Y Minutolo et al. (2016)  
Solanaceae  Capsicum  annuum  (red pepper)  Vein clearing, mosaic, malformation, 
local chlorosis, yellow mosaic  Y Kwak et al . (2013); Svoboda and 
Leisova -Svobodova (2013)  
 C. frutescens  (tabasco pepper)   Y Lisa and Boccardo (1996)  
 Datura  stramonium  (jimsonweed)  Asymptomatic  N Fuji et al. (2 007) 
 Nicotiana  benthamiana  Mosaic, chlorotic ringspots, mottle, 
leaf distortion, vein clearing  N Fuji et al. (2007)  
 N. clevelandii  Asymptomatic  N Fuji et al. (2007)  
 N. debneyi  Asymptomatic  N Fuji et al. (2007)  
 N. glutinosa  Asymptomatic  N Fuji et al. (2007)  
 N. occidentalis  Mosaic  N Fuji et al. (2007)  
 N. rustica  Mottling  N Fuji e t al. (2007)  
 N. tabacum  (tobacco)  Asymptomatic  Y Fuji et al. (2007); (Akinyemi et al. 2016)  
 Petunia  sp. Mosaic  Y Lesemann (1996)  
 Physalis  floridana  (groundcherries)  Mosaic  N Wei and Li (2017)  
 Solanum  lycopersicum  (tomato)   Y Liu et al. (2019)  
 S. melongena  (eggplant)  Stunting, necrosis, yellow mosaic  Y Rui et al. (2020)  
Tropaeolaceae  Tropaeolum  majus  (nasturtium)  Chlorotic spots, mosaic  Y Wei and Li (2017)  
Valerianaceae  Valeriana  fauriei  Stunting, mosaic (in co -infection), 
slight yellowing (in single infection)  Y Uehara -Ichiki et al. (2020)  
 Valeriana  officinalis  (valerian)  Asymptomatic  N Uehara -Ichiki et al. (2020)  
Verbenaceae  Verbena  sp. (verbena)   Y Harju et al. (2011)   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 58 Distribution  
 
Isolates of BBWV -2 have been detected in  parts of  Asia and Europe, and in the USA, Australia, 
Argentina, and South Africa ( Table 8 ). There are also reports of broad bean wilt virus  in France, 
Greece, Egypt, and Bulgaria where the species or serotype has not been specified (Sastry et al. 
2019) . The virus may also be present in Israel, as a sample of Salvia officinalis  tested in the UK , but 
reportedly obtained from Israel , tested positive (Mumford et al. 2006) . Petunia ringspot virus  has been 
identified in India, however, there is conflicting information available in the literature on wh ether  this 
virus is a strain of BBWV -2 or BBWV -1 (Lisa and Boccardo 1996; Virus Taxonomy 2012; Sastry et al. 
2019) .  
 
Table  8: Reported distribution of broad  bean wilt v irus 2 .  
Region  Country  Reference  
Asia China  Sui et al. (2009)  
 Japan  Fuji et al. (2007)  
 South Korea  Kwak et al. (2013)  
 Singapore  Koh et al. (2001)  
 Taiwan  Shen et al. (2012)  
 Philippines  Ferrer et al. ( 2011)  
 Indonesia  Miftak hurohmah et al. (2015)  
Europe  Germany*  Verhoeven et al. (2002)  
 Netherlands*  Verhoeven et al. (2002)  
 Spain*  Sastry et al. (2019)  
 Italy*  Minutolo et al. (2016)  
 UK* Mumford et al. (2006)  
 Czech Republic  Svoboda and Leisova -Svobodova (2013)  
Oceania  Australia*  Shukla et al. (1980)  
North America  USA*  Scott and Barnett (1984)  
South America  Argentina  Gracia and Feldman (1976)  
Africa  South Africa  Jooste et al. (2001)  
*Indicates countries that are currently on the list of approved countries for the importation of 
Alstroemeria  nursery stock (MPI 2020) . 
 
Symptoms  
 
A wide range of symptoms are observed for BBWV -2 in different hosts, including mosaic, mottling, 
chlorotic spots, necrotic spots, ring spots, leaf yellowing, vein clearing, stunt ing, leaf distortion, wilting, 
and apical necrosis  (Table 7 ). Plant death is reported in broad beans (Wei and Li 2017) . In 
Alstroemeria , the virus is reported to caus e stunting and necrosis in mature plants, and mosaic 
symptoms in inoculated seedlings (Fuji et al. 2007) . Symptoms of BBWV -2 may be more pronounced 
in cool conditions (Sastry et al. 2019) . Asymptomatic infections are reported in some species (Shukla 
et al. 1980; Fuji et al. 2007) . Many isolates of BBWV -2 are detected in coinfection with other common 
virus  species  such as Cucumber mosaic virus  (CMV). These coinfections make it difficult to discern 
the impact of BBWV -2 alone. However, infection with multipl e viruses can have a synergistic effect, 
leading to more severe  symptoms (Kwak et al. 2013) .   
 
 
 
Vectors  
 
Several aphid species are known to  vector  BBWV -2 in a non -persistent manner, which enables them 
to transmit the virus to other hosts for several minutes and up to a few hours (Pirone and Perry 2002) .  
The most efficient vectors are reported to be Aphis gossypii  and Myzus persicae , with an infection 
rate of 60 -90% (Kwak et al. 2013) . Table 9 shows the currently identified aphid vectors of BBWV -2, 
five of which are known to be present in New Zealand.  
  
59 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Table  9: Insect vectors of Broad bean wilt virus 2.  
Vector species (common name)  Reference  
Acyrthosiphon pisum  (pea aphid) *  Dunich and Mishchenko (2015)  
Acyrthosiphon solani  Sastry et al. (2019)  
Aphis craccivora  (cowpea aphid) *  Dunich and Mishchenko (2015)  
Aphis fabae  (black bean aphid)  Dunich and Mishchenko (2015)  
Aphis gossipii (cotton aphid) *  Kwak et al. (2013)  
Aphis nasturtii (buckthorn -potato aphid)  Dunich and Mishchenko (2015)  
Macrosiphon euphorbiae  (potato aphid) syn. Macrosiphon 
solanifolii *  Dunich and Mishchenko (2015)  
Myzus persicae  (green peach aphid) *  Dunich and Mishchenko (2015)  
*Indicates species present in NZ (NZOR 2021) . 
 
6.1.5 Likelihood of entry:  
Association with Alstroemeria  
No reports were found of BBWV -2 being associated with Alstroemeria  in South Africa or India. The 
association of BBWV -2 with Alstroemeria  has only been reported from Japan , where  Kobayashi et al. 
(2009)  reported a weak reaction of Alstroemeria  samp les collected in Nagano prefecture to BBWV -2 
antiserum. Natural infection of Alstroemeria  with BBWV -2 was confirmed by reverse transcription PCR 
(RT-PCR) (Fuji et al. 2007) . From a total of 72 Alstroemeria  samples taken by Fuji et al. (2007) in 
Hokkaido, Aichi, and Nagano (59, 8, and 5 samples  respectively) BBWV -2 was only detected in a 
single sample ( Alstroemeria cv. Red Velvet) with symptoms of stunting and necrosis . Previous testing 
of Alstroemeria  plants from Italian nurseries found no incidence of infection with BBWV -2 (Luvisi et al. 
2016) .  
 
Presence in Exporting  Countries  
A literature search in Google Scholar using the search terms “Broad bean wilt viru s 2” AND “South 
Africa” found one source indicating BBWV -2 presence in South Africa (Jooste et al. 2001 ). This report 
is based on an early detection of a virus in Pisum sativum  which was identified as Broad  bean wilt 
virus serotype II. Isolates of this serotype are now considered to belong to the BBWV -2 species. No 
other records were  found of BBWV -2 infection of Alstroemeria  or other plant species in South Africa .  
 
BBWV -2 is listed as a quarantine pest in I ndia (ONZPR 202 1), which suggests that the virus has not 
been detected in India . A Google scholar search with the terms “Broad bean wilt virus 2” AND “India” 
produced no results , also indicating  that BBWV -2 is not present in India. However, Petunia ringspot 
virus, a possible strain of BBWV -2, was identified on Petunia sp. in India (Mali et al. 1977) . There is 
conflicting information in the available li terature on whether  this virus is a strain of BBWV -2 or BBWV -
1 (Lisa and Boccardo 1996; Virus Taxonomy 2012; Sastry et al. 2019) .  
 
Detection  
Back -inoculation experiment s demonstrated infection of BBWV -2 in Alstroemeria  seedlings , and 
mosaic symptoms developed in the seedlings within three months of inoculation (Fuji et al. 2007) . The 
infection by BBWV -2 was confirmed by RT -PCR. Symptoms observed on natural and experimentally 
infected Alstroemeria  are variabl e, suggesting that infection in Alstroemeria  may manifest in different 
ways  but it is expected that symptoms will be observ able. Therefore, cells are unlikely to  be collected 
from infected plants for propagation as tissue culture,  but any symptoms of the d isease may not be 
observed in tissue culture  inspections. For example, s ymptoms of stunting alone would not be visible 
in tissue culture samples. Asymptomatic infection of BBWV -2 has been reported in other host 
species , particularly in experimentally infected species  (Shukla et al. 1980; Fuji et al. 2007) . As very 
few infections of BBWV -2 have been reported in Alstroemeria , the symptoms of the virus , and 
therefore its ability to be detected during tissue culture inspections is uncertain.  
 
There is uncertainty regarding the association of BBWV -2 with Alstroemeria , other hosts and their 
symptoms,  and the distribution of the virus because:  
• the original classification of BBWV -2 as a serotype of BBWV means that many early studies 
did not specify or determine the serotype of isolates (Mumford et al. 2006) .   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 60 • generally, BBWV -2 is not recognised to cause major disease of economically important crops. 
Therefore, there are low rates of testing for the virus except when significant outbreaks occur 
(Lisa and Boccardo 1996) . 
• BBWV -2 is frequently found in co -infections with other common crop viruses, such as CMV, 
so the symptoms and impacts of BBWV -2 may often be  attributed to other viruses (Kwak et 
al. 2013; Liu et al. 2019) .  
Given the arguments and evidence above, the likelihood of BBWV -2 entering New Zealand 
associated with Alstroemeria  tissue culture , from So uth Africa , is considered to be very low, with high 
uncertainty.  No records were found  of BBW V-2 being present in India but there is uncertainty due to 
taxonomic difficulties. L ikelihood of entry from India is considered negligible -very low with moderate  
uncertainty , due to the uncertainty surrounding the presence /absence  of the virus in India, resulting 
from the paucity of records and taxonomic difficulties.   
6.1.6 Likelihood of exposure:  
Imported Alstroemeria  tissue culture is expected to be maintained in a fa vourable habitat for survival 
of plant material and be multiplied in substantial numbers, thereby promoting the persistence and 
exposure of associated pathogens. Because Alstroemeria  is a perennial species, systemic infections 
of BBWV -2 will remain viable within the plant for a number of seasons, providing an ongoing source of 
inoculum. Aphid vectors and mechanical inoculation can be expected to transmit BBWV -2 between 
plants within a nursery setting.  
Given the arguments and evidence above, the likelihood of exposure of BBWV -2 in New Zealand 
from Alstroemeria  tissue culture is considered high, with low  uncertainty.  
6.1.7 Likelihood of establishment:  
BBWV -2 is widely distributed, including in countries with high climate similarity with New Zealand (e.g. 
Spain, CMI =0.8-0.9; Germany, CMI=0.9; Italy, CMI=0.8 -0.9) (Phillips et al. 2018 ). Therefore, there is 
unlikely to be any climatic barrier to prevent its establishment and spread.  It is considered likely that 
the virus is present in many more countries than is reported because testing for the virus has been 
limited (CABI 2021) . The climate similarity of the known distribution with New Zealand ranges from 
CMI 0.3 to 0.9 (Phillips et al. 2018) . Climate will primarily influence the distribution of BBWV -2 through 
the distribution of hosts and vectors. However, viruses have different temperature optima for their 
multiplication within plant hosts (Jones 2012) . This may result in the more pronounced symptoms that 
have been observed for BBWV -2 at low temperatures (Sastry et al. 2019) .  
The virus can be expected to spread rapidly once established. Kwak et al. (2013)  reported an 
incidence rate of 2% in red capsicum field samples in Korea in 2004, which rapidly increased to 79% 
in 2007. Many known host species  (Table 7 ) of BBWV -2 are common and widespread in New 
Zealand, therefore availability of hosts will not pose any barrier to the establishment and spread of the 
virus. Known insect vectors of BBWV -2 are present in New Zealand (Table 9).  and will therefore 
enable the establishment and spread of the virus. Vector  transmission is nonpersistent (retaining the 
ability to transmit the virus for a few minutes up to several hours) so vectors will be able to transmit 
the virus over short distances (Pirone and Perry 2002; Sastry et al. 2019) . The suitability of climate 
conditions for BBWV -2 establishment will be primarily linked to climate favourability to aphids (Kwak 
et al. 2013) .  
Several sour ces state that the virus is not seed transmitted (Dunich and Mishchenko 2015) . 
Provvidenti (1988)  found no instances of seed transmission from 171 seeds of beans infected with 
BBWV (serotype unknown). However, seed transmissi on of BBWV -1 has been reported in broad 
bean at a very low rates (0.4 -0.6%) (Makkouk et al. 1990) . Putz and Kuszala (1973)  reported low 
seed transmission rates of BBWV (serotype unknown) but suggest that even at this level it may 
provide a sufficient source of inoculum in the field which may contribute to the long -term 
establishment of the virus within a location. No evidence was found in the literature of seed 
transmission of virus confirmed to be BBWV -2. Therefore, it is considered that the potential for seed 
transmission of BBWV -2 is very low but is not negligible.  
Long distance human mediated transmission of BBWV -2 may also occur through the distribution of 
infected, asymptomatic propagative material.    
61 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Given the arguments and evidence above, the likelihood of BBWV -2 establishing in New Zealand is 
considered high, with low uncertainty.  
6.1.8 Impacts in New Zealand:  
Given the broad host range of BBWV -2, it is likely to have widespread impacts in New Zealand. 
Outbreaks of the disease are likely to occur in seasons wh ere populations of aphid vectors are high 
and can be expected to have impacts on the productivity of horticultural species and to the value of 
ornamental plants (Kwak et al. 2013) . The infection of perennial plants and weedy species will provide 
ongoing sources of inoculum that would likely make eradication of the virus unfeasible.  
 
e) Economic impacts  
While BBWV -2 is often considered a low impact virus and outbreaks are rare, it is reported to cause 
significant damage in some economically important horticultural and ornamental plant species when 
outbreaks occur (Lisa and Boccardo 1996; Ferrer et al. 2011) . The virus has a broad host range and 
is reported naturally infecting at least 41 diffe rent plant genera from 24 families. However, due to 
limited testing for the virus and its original classification as a serotype of broad bean wilt virus, the 
specific hosts of BBWV -2 are often unclear and are likely underestimated (Mumford et al. 2006) .  
Broad bean wilt virus 2 is primarily reported causing symptoms on the leaves of host plants, with a 
few sources reporting infections on plant stems ( Table 7 ). Vegetable crops that are harves ted for their 
leaves, such as beets, spinach, and lettuce, will likely be significantly affected by outbreaks of BBWV -
2, because symptoms of the virus will make the products unmarketable. The economic values of 
important vegetable hosts of BBWV -2 are prese nted in  Table 10 . Lee et al. (2000)  reported BBWV -2 
causing flowers to drop or immature fruit to wilt on Capsicum  annuum  (pepper).  Other typical 
symptoms of the virus, such a necrosis, leaf deformation and chlorosis, are likely to affect the 
photosynthetic capabilities of plants, which, along with stunting, is likely to result in reduction of yield 
for fru iting crops.  
Mixed infections with other common viruses are reported to have synergistic effects that enhance 
symptom expression and thereby may increase damage to important crops (Kwak et al. 2013) . Mixed 
infection of BBWV -2 with CMV is frequently reported and is attributed to an increase in damages to 
pepper plants in Korea (Kwak et al. 2013) . Cucumber mosaic virus  is present and widespread in New 
Zealand (Veerakone et al. 2015) . Therefore, the establishment of BBWV -2 in New Zealand and its 
potential synergistic impacts with CMV may increase the effects of these viruses on horticultural 
industries in New Zealand. Given that the total value of ind ustries that may be affected by BBWV -2 in 
New Zealand exceeds $477 million ( Table 10 ), even a small decrease in yield would result in a 
significant economic impact to New Zealand. Therefore, the economic impact of BBWV -2 to New 
Zealand is considered to be moderate , with moderate uncertainty.  
 
 
 
 
 
 
 
 
  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 62 Table  10: New Zealand industry values of some economically important hosts of BBWV -2 and 
reported disease impacts on these hosts. Industry values from Plant & Food Research (2019) . 
– is used when data is not available  
Host   Domestic value 
(2018)  Export value 
(2019)  BBWV -2 
impacts  
Beet  $8m $24.8m  Chlorotic spots, 
mottling  
Spinach   $12m  - - 
Lettuce ( L. sativa )  $42m  $0.8m  - 
Legumes  Peas  $25m  $96.5m  Chlorotic ring 
spots,  stem 
necrosis, mosaic  
 Beans  $10.3m  $41.1m  Leaf necrosis, 
wilt, mosaic, 
chlorotic spots, 
plant death  
Solanaceae  Pepper  $8.5m  - Vein clearing, 
mosaic, 
malformation, 
local chlorosis, 
yellow mosaic, 
wilting of fruit and 
flowers  
 Tomato  $185.1m  $14.5m  - 
 Eggplant  $8.5m  - Stunting, 
necrosis, yellow 
mosaic  
 
f) Environmental  impacts  
Natural infection of BBWV -2 is reported in 24 different plant families, of which 16 include species 
native to New Zealand (NZPCN 2021) . Genera of New Zealand native species with environmental 
value that may be susceptible to infection by BBWV -2 include Carmichaelia (New Zealand brooms), 
Clianthus , Sophora  (kōwhai), Tetragonia , and Veronica . Impacts on these species are unknown and 
may range from asymptomatic infection to plant death.   
Infection of weedy species such as periwinkle, foxglove, ribwort plantain and London rocket may 
provide a mode for BBWV -2 to spread into native habitats in New Zealand. For example, periwinkle is 
an exotic species that is naturalised in New Zealand, and in vasive populations can be found in natural 
habitats. Symptomless infection of BBWV -2 in rose periwinkle  (Catharanthus  roseus ) has been 
reported in Australia (Shukla et al. 1980) . 
Given the arguments and evidence above, the impacts on the environment of BBWV -2 to New 
Zealand is considered to be low, with moderate uncertainty.  
g) Health  impacts   
63 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  There are no known health impacts associated with BBWV -2. As such, the health impacts of BBWV -2 
to New Zealand is considered to be negligible , with low uncertainty.  
 
h) Social/cultural  impacts  
Establishment of BBWV -2 can be expected to have social impacts as it infects several vegetable 
crops that are widely grown  in home gardens throughout New Zealand. Infection of ornamental 
species will also have social impacts due to the reduction of their amenity value.  
Some endemic potential hosts (species that belong to genera or families that are known to be infected 
by BBW V-2) of BBWV -2 have significant cultural and social values to New Zealand. For example, 
kōwhai has a wide range of traditional uses in M āori culture, including medicine, dyes, and 
construction. Kakabeak is prized as a decorative plant in M āori cultural and  continues to be an 
ornamental feature of New Zealand gardens. There are numerous endemic Rananculus  species in 
New Zealand, including R. lyalii  (Mount Cook buttercup) which is symbolic of New Zealand’s alpine 
scenery.  
Given the arguments and evidence above, the social/cultural  impacts of BBWV -2 to New Zealand are 
considered to be low , with moderate uncertainty.  
6.1.9 Management considerations  
Assurance of Pest Free Area (PFA)  
A PFA officially confirms that the pathogen is not present in the area being considered and includes 
requirements for the use of measures to maintain and verify freedom from the specified pathogen 
(FAO 2017) . The unce rtainty regarding the overall risk of BBWV -2 is largely due to the lack of testing 
for the virus. Assurance of a PFA would require testing to prove the absence of the virus, and thereby 
considerably reduce the risk of entry and uncertainty. It is considere d that a PFA for BBWV -2 would 
reduce the likelihood of entry to New Zealand on Alstroemeria tissue culture to negligible, with low 
uncertainty. This would reduce the overall level of risk to negligible, with low uncertainty.   
 
Assurance of Pest Free Place  of Production (PFPP)  
A PFPP would require that mother plants used to produce tissue culture are tested to ensure they are 
free of BBWV -2 (FAO 2016) . Therefore, it is cons idered that a PFPP for BBWV -2 would reduce the 
likelihood of entry to New Zealand on Alstroemeria tissue culture to negligible, with low uncertainty. 
This would reduce the overall level of risk to negligible, with low uncertainty.  
 
Molecular  testing  
Positi ve identifications of BBWV -2 infection frequently use a combination of ELISA and PCR 
techniques.  
• Polymerase Chain Reaction (PCR) : There are published q uantitative real -time reverse 
transcription PCR (RT-qPCR) assay  for the specific detection of BBWV -2 (Ferriol et al. 2011) . 
Previously, BBWV -2 have been detected in Alstroemeria using primer sequences described 
by Kondo et al. (2005) . Numerous primer pairs for diagno sis of BBWV -2 are described by 
Kwak et al. (2013)  
• Enzyme -linked immunosorbent assay (ELISA) : Infection of BBWV -2 is often identified through 
reactions to virus specific polyclonal antibodies, such as those described by Kobayashi et al. 
(2009) , Mumford et al. (2006) , and Fowkes et al. (2017) .   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 64 Molecular testing of mother plants  is considered to reduce the likelihood o f entry to negligible. This 
would reduce the overall level of risk to negligible, with low uncertainty.  
 
Growth in Post Entry Quarantine (PEQ)  
Inoculation experiments for Alstroemeria  has shown that symptoms of BBWV -2 are expressed in 
seedlings within three months. Therefore, it appears likely that disease symptoms would appear in 
infected plants during a quarantine period. However, asymptomatic infection by BBWV -2 is reported 
in some species, and the only study of the virus in Alstroemeria  reported inconsistent symptoms in 
mature plants vs. seedlings. As the time need to express symptoms of BBWV -2 in Alstroemeria  in 
tissue cultures has not been studied, it cannot be determined what per iod of PEQ is appropriate to 
reduce the likelihood of entry to a negligible level. Therefore, containment and inspection of 
Alstroemeria  tissue culture in PEQ is not considered to lower the risk of entry for BBWV -2 to a 
negligible level. However, combining  this management method with pre -determined testing is 
considered to reduce the likelihood of entry to negligible. This would reduce the overall level of risk to 
negligible, with low uncertainty.  
 
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69 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand   
Appendix 1.  Summary of taxa excluded  at hazard identification  
Appendix 1, Table 1 Species identified (at the hazard identification  stage ) as not requiring further assessment or measures over and above basic measures, with 
the rationale for exclusion  
Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Bacteria  
Aster yellows group 
(16SrI) subgroup G  Insufficient information was found regarding this subgroup of the 16SrI group of phytoplasmas. Subgroup G of the 16SrI group is 
not listed in CABI (CABI 2021) or by Seemüller et al. (1998).  No further example of 16SrI -G being associated with Alstroemeria 
was found. The only other reference 16SrI -G found was from Ulmus in Italy (Lee et al. 1995). It appears that this subgroup may 
no longer be used and there is insufficient information to justify an assessment.   
Group 16SrIII (X 
disease) phytoplasma  There is insufficient information to conduct  an assessment.  The subgroup is not given in the source literature ( Bertaccini et al. 
1996 ). Given that there are many different reported subgroups , with different host ranges (MPI 2021) and one subgroup  is 
present in New Zealand (Veerakone et al. 2015), there is insufficient information provided to conduct a risk assessment.     
Fungi   
Alternaria alstroemeriae  
Simmons & Hill, 2007  There are some reports of association of Alternaria spp. with tissue culture, but only as contaminants due to poor hygiene or 
contamination by small invertebrates (not direct transmission), e.g. Omamor et al. (2007), Blake (1987), Lumsden et al. (2012 ). 
Therefore, it is considered that this species would no t be associated with the commodity.  
Urocystis alstroemeriae 
Vánky & V ánky, 1999  Insufficient information for an assessment. The only reference found for U. alstroemeriae  was the single record  in NZFungi2 
database (2021). There is a clear host association, but it may not be associated with the commodity. There is also insufficie nt 
information available to determine the distribution and host range of the fungus. If any further information become s available,  it 
will be captured via the emerging risks system and the risk reassessed as required.    
Nematodes   
Pratylenchus bolivian us 
Corbett, 1983  Present in N ew Zealand  (Aalders et al. 2017) and is non -regulated  (ONZPR 2021) . 
Zygotylenchus guevarai  
(Jiménez, 1963) Braun & 
Loof, 1966  Present in N ew Zealand  (NZOR 2021) and is non -regulated  (ONZPR 2021) .  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 70 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Oomycetes   
Globisporangium 
irregulare  (Buisman) 
Uzuhashi, Tojo & Kakish, 
2010  (syn. Phythium 
irregulare ) Present in N ew Zealand (NZFungi 2021)  and non -regulated  (ONZPR 2021) .  
Globisporangium  
ultimum  (Trow) 
Uzuhashi, Tojo & Kakish, 
2010 (syn. Pythium 
ultimum )  Present in New Zealand (NZFungi 2021) and non -regulated (ONZPR 2021).  
Viruses   
Alstroemeria mosaic 
virus (AISV)  (syn. 
Alstroemeria streak 
virus ) Present in N ew Zealand and has been isolated from Alstroemeria sp. (Veerakone et al. 2015) . No evidence of different strains of 
this virus was found in the literature.   
Alstroemeria necrotic 
streak orthotospovirus  
(ANSV)  (syn. 
Alstroemeria necrotic 
streak  virus ) No evidence was found of the virus being present in India  or South Africa. ANSV has been reported from Colombia (Gallo et al. 
2019; Hassani -Mehraban et al. 2010; Olaya et al. 2017)  and the USA (Tian et al. 2019). The report of the virus in Hoya  spp. in 
the USA (exported from Guatemala and Thailand) was the first report of the virus outside of Colombia.  
Alstroemeria virus X  
(AlsVX)  No evidence was found of the virus being present in India  or South Africa. The virus has been reported from Alstroemeria sp. in 
Finland, Japan and Norway (Fuji et al . 2005; Bi et al. 2012) . 
Alstroemeria yellow spot 
orthotospovirus  (AYSV)  
(syn. Alstroemeria yellow 
spot virus  No evidence was found that the virus is present in India and South Africa, and there is insufficient information available on the 
virus for an assessment. There is only one report of this virus in the literature (Hassani -Mehraben et al. 2019). The diseased 
plants were tested in the Netherland s, though plant origin is unknown. The paper mentions that this is a tentative name and there 
are no further papers  suggesting that this is confirmed. Currently only reported from Alstroemeria and had a narrow experimental  
host range. Currently insufficient information for a full assessment and does not appear a risk. Will be monitored  via the emerging 
risk system .  
71 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Arabis mosaic virus 
(ArMV)  (syn. Arabis 
mosaic nepovirus,  
Arabis mosaic nepovirus  
[hop nettlehead strain],  
Arabis mosaic virus,  
Ash ring and line pattern 
virus,  
Forsythia yellow net 
virus,  
Raspberry yellow dwarf 
virus,  
Rhabarber -mosaik -virus,  
Rhubarb mosaic virus ) Present in New Zealand  (Veerakone et al. 2015) and non -regulated (ONZPR 2021) ; the virus is not regulated on the basis of 
strains. There are reports of different strains of this virus on hops and Rubus spp. (EPPO datasheet undated). ArMV has been 
isolated from these hosts in New Zealand (Veerakone et al. 2015). No evidence was found that ArMV associated with 
Alstroemeria represent s a strain that is not present in New Zealand.  
Cucumber mosaic virus  
(CMV) (syn. Cucumber 
mosaic cucumovirus, 
Cucumber virus 1 , 
Daphne isometric virus -
1, Daphne mosaic, 
Leucanthe Variegata  
virus -1, Tamarillo 
bootlace and Tree 
tomato bootlace, Violet 
mosaic ) Present in New Zealand and has been isolated from Alstroemeria sp. (Veerakone et al. 2015) . The virus  is non-regulated 
(ONZPR 2021).   
Dasheen mosaic virus  
(DsMV) (syn. Dasheen 
mosaic po tyvirus ) Present in New Zealand (Veerakone et al. 2015) and is non-regulated (ONZPR 2021).  Although different strains of the virus have 
been determined, no evidence was found of any of the described stains being associated with Alstroemeria species.  
Freesia mosaic virus  
(FreMV) (syn. Spiranthes 
mosaic virus 2, Freesia 
mosaic potyvirus ) Present in New Zealand (Veerakone et al. 2015) , the regulatory status has not been assessed (ONZPR 2021) . We found no  
evidence that the virus has recognised strains .   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 72 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Grapevine Algerian 
latent virus  (GALV) (syn. 
Grapevine Algerian 
latent tombusvirus ) No evidence was found that the virus is in India and South Africa ( Google Scholar: grapevine Algerian latent virus India and 
grapevine Algerian latent virus South Africa).  
Impatiens necrotic spot 
orthotospovirus  (INSV ) 
(syn. Impatiens necrotic 
spot virus ) Present in New Zealand (Veerakone et al. 2015) , the regulatory status has not been assessed (ONZPR 2021) . No evidence of 
the virus having different strains was found.  
Iris yellow spot 
orthotospovirus  (IYSV) 
(syn. Iris yellow spot 
virus ) Present in New Zealand (Veerakone et al. 2015) , the regulatory status has not been assessed (ONZPR 2021) . No evidence of 
the virus having different strains was found.  
Lily symptomless v irus 
(LSV)  (syn. Alstroemeria 
carlavirus, Lily curl stripe 
virus, Lily streak virus,  
Lily symptomless 
carlavirus ) Present in New Zealand (Veerakone et al. 2015) and non -regulated (ONZPR 2021).  The virus is not regulated on a strain - basis 
and no evidence of the virus having recognised strains was found.  
Lily mottle virus  (LMoV) 
(syn.  Lily mottle 
potyvirus ) Present in New Zealand (Veerakone et al. 2015) and non -regulated (ONZPR 2021).  The virus is not regulated on a strain -basis 
and no evidence of the virus having recognised strains was found.  
Ornithogalum mosaic 
virus  (OrMV) (syn. 
Ornithogalum mosaic 
potyvirus, Ornithogalum 
stripe mosaic virus ) Present in New Zealand (Veerakone et al. 2015) and non -regulated (ONZPR 2021).  The virus is not regulated on a strain -basis 
and no evidence of the virus having recognised strains was found.   
73 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Pepper huasteco yellow 
vein virus  (PHYVV) (syn. 
Pepper huasteco 
begomovirus, Pepper 
huasteco bigeminivirus,  
Pepper huasteco virus,   
Pepper huas teco yellow 
vein begomovirus ) No evidence was found that the virus is in India and South Africa. PHYVV has only been  reported from Alstroemeria in Mexico  
(Cervantes -Díaz 2009 ). The v irus is also described  from USA and Guatemala (CABI 2019).  
Tobacco rattl e virus  
(TRV) (syn. Tobacco 
rattle nepovirus, Tobacco 
rattle tobravirus , Paeony 
ringspot virus ) Present in New Zealand and has been isolated from Alstroemeria sp. in New Zealand (Veerakone et al. 2015) . The virus is 
regulated based on strains present/not present in New Zealand (ONZPR 2021). B ased on the fact that the virus has been 
isolated from Alstroemeria in New Zealand, it is concluded that TRV associated with Alstroemeria represents a strain already 
present in New Zealand.   
Tobacco streak virus  
(TSV ) (syn. Asparagus 
stunt virus, Black 
raspberry latent ilarvirus, 
Datura quercina virus, 
Necrotic shock virus, 
Tobacco streak ilavirus)  Present in New Zealand (Veerakone et al. 2015).  Strains of TSV in New Zealand are non -regulated, however, strains not in New 
Zealand are regulated (ONZPR 2021). Although different strains of TSV have been recognised, no evidence was found of TSV 
associated with Alstroemeria representing a strain that is not present in New Zealand.  
Tomato yellow ring 
orthotospovirus  (TYRV) 
(syn. Tomato fruit yellow  
ring virus , Tomato yellow 
ring virus, Tomato 
varamin virus,  Tomato 
yellow ring virus ) The virus is not known from India or South Africa.  The virus is reported from Iran (Winter et al. 2006; Beikzadeh et al. 2012), 
Kenya (Birithia  et al. 2012) and Poland (Zarynska -Nowak et al. 2016).  TYFRV is not known to occur in New Zealand and is 
regulated (ONZPR 2021).   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 74 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Tomato spotted wilt 
orthotospovirus  (TSWV) 
(syn.  Dahilia oakleaf, 
Dahlia oakleaf virus, 
Dahlia ringspot, Dahlia 
ringspot virus, Mung 
bean leaf curl virus, 
Pineapple yellow spot 
virus,  Tomato spotted 
wilt virus ; Tobacco black 
wilt, Tomato bronze top , 
Watermelon silver  mottle 
virus ) Present in New Zealand (Veerakone et al. 2015) and non -regulated (ONZPR 2021).  The virus is not  regulated on the basis of  
strains , and no evidence was found of the virus having strains that may not be present in New Zealand.   
Youcai mosaic virus  
(YoMV)  No evidence was found that the virus is in India and South Africa. Virus is reported from Korea,  China, Japan, Germany, UK, 
Spain, Switzerland (Ju et al. 2019). The only record of the virus being isolated from Alstroemeria was from Japan (Fuji et al . 
2007 ). 
Zantedeschia mild 
mosaic virus  (ZaMMV)  Present in New Zealand (Veerakone et al. 2015) , the v irus is not recorded in ONZPR (2021) . No evidence was found of the virus 
having strains that may not be present in New Zealand.   
Konjac mosaic virus 
(KoMV)  (syn. 
Zantedeschia mosaic 
potyvirus ; Zantedeschia 
mosaic virus ) Present in New Zealand (Veerakone et al. 2015)  and is non -regulated  (ONZPR 2021) . The virus is not regulated on a strains 
basis and no evidence was found of the virus having strains that may not be present in New Zealand.   
 
 
 
  
75 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  References for Appendix 1  
Aalders, L T; McNeill, M R; Bell, N  L; Cameron, C (2017) Plant parasitic nematode survival and detection to inform biosecurity risk assessment.  NeoBiota,  36: 
1. 
Beikzadeh, N; Bayat, H; Jafarpour, B; Rohani, H; Peters, D; Hassani -Mehraban, A (2012) Infection of Alstroemeria Plants with Tomat o yellow ring virus in 
Iran. Journal of Phytopathology,  160(1): 45 –47. 
Bi, Y; Tugume, A K; Valkonen, J P (2012) Small -RNA deep sequencing reveals Arctium tomentosum as a natural host of Alstroemeria virus X and a new 
putative Emaravirus.  PLoS One,  7(8), p. e42758.  
Birithia, R; Subramanian, S; Villinger, J; Muthomi, J W; Narla, R D; Pappu, H R (2012) First report of Tomato yellow ring vir us (Tospovirus, Bunyaviridae) 
infecting tomato in Kenya.  Plant Disease,  96(9): 1384 –1384.  
Blake, J (1987) Mites and thrips as bacterial and fungal vectors between plant tissue cultures. Bacterial and Bacteria -like Contaminants of Plant Tissue 
Cultures 225: 163 –166. Abstract only, available at: http://www.actahort.org/books/225/225_17.htm)  
CABI (2019)  Pepper huasteco yellow vei n virus https://www.cabi.org/isc/datasheet/41001 Accessed 16 June 2021  
CABI (2021) ‘Candidatus Phytoplasma asteris’ (yellow disease phytoplasma) In: Crop Protection C ompendium https://www.cabi.org/isc/datasheet/7642 
Accessed July 2021  
Cervantes -Díaz, L; Zavaleta -Mejía, E; Rojas -Martínez, R I; Alanís -Martínez, I; Ochoa -Martínez, D L; Val adez -Moctezuma, E; Grimaldo -Juárez, O (2009) 
Detección de geminivirus asociados a la alstroemeria (Alstroemeria L.) en villa guerrero, estado de México.  Interciencia,  34(12): 903 –908. 
EPPO datasheet (undated) Data sheets on quarantine pests Arabis mosaic n epovirus https://gd.eppo.int/download/doc/28_datasheet_ARMV00.pdf  
Fuji, S; Shinoda, K; Ikeda, M; Furuya, H; Naito, H; Fukumoto, F (2005) Complete nucleotide sequence of the new potexvirus “Al stroemeria virus X”.  Archives 
of virology,  150(11): 2377 –2385.  
Fuji, S I; Mochizuki, N; Fujinaga, M; Ikeda, M; Shinoda, K; Uematsu, S; Furuya, H; Naito, H; Fukumoto, F (2007) Incidence of viruses in Alstroemeria plants 
cultivated in Japan and characterization of Broad bean wilt virus -2, Cucumber mosaic virus and Youca i mosaic virus. Journal of General Plant Pathology, 
73(3): 216 –221. 
Hassani -Mehraban, A; Botermans, M; Verhoeven, J T J; Meekes, E; Saaijer, J; Peters, D; Goldbach, R; Kormelink, R (2010) A distinct to spovirus causing 
necrotic streak on Alstroemeria sp. in  Colombia.  Archives of Virology,  155(3): 423 –428.  
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 76 Ju, H K; Kim, I H; Hu, W X; Kim, B; Choi, G W; Kim, J; Lim, Y P; Domier, L L; Hammond, J; Lim, H S (2019) A single nucleotide  change in the overlapping MP 
and CP reading frames results in differences in sym ptoms caused by two isolates of Youcai mosaic virus.  Archives of Virology,  164(6): 1553 –1565.  
Lee, I M; Bertaccini, A; Vibio, M; Gundersen, D E; Davis, R E; Mittempergher, L; Conti, M; Gennari, F (1995) Detection and ch aracterization of phytoplasmas 
associ ated with disease in Ulmus  and Rubus  in northern and central Italy.  Phytopathologia Mediterranea : 174 –183. 
Lumsden, P J; Nicholas, J R; Davies, W J (Eds) (2012) Physiology, growth and development of plants in culture. Springer Scien ce & Business Media. 
Available at: 
https://books.google.co.nz/books?id=p8PrCAAAQBAJ&pg=PA399&lpg=PA399&dq=alternaria+species+in+plant+tissue+culture&source=bl&o ts=GMKqbt7mU
O&sig=xNIOWe27IrodB7b1C4EbJXG1OHM&hl=en&sa=X&ved=0ahUKEwiY -
ayx65HYAhVKXLwKHXGSBaMQ6AEIZDAN#v=onepage&q=alternaria%20s pecies%20in%20plant%20tissue%20culture&f=false . 
MPI (2021) Scientific and technical advice_Phytoplasmas on nursery stock grouped PRA tables  
NZFungi (2021) Manaaki Whenua -Landcare Research Database. https://nzfungi2.landcareresearch.co.nz/  Accessed June 2021  
Omamor, I B; Asemota, A O; Eke, C R; Eziashi, E I (2007) Fungal contaminants of the oil palm tissue culture in Nigerian insti tute for oil palm research 
(NIFOR). African journal of agricultural r esearch 2 (10): 534 –537. Available at: 
https://www.researchgate.net/publication/22836 0106_Fungal_contaminants_of_the_oil_palm_tissue_culture_in_Nigerian_institute_for_oil_palm_research_NI
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ONZPR (2021) Official New Zealand Pest Register https://pierpes tregister.mpi.govt.nz/PestsRegister/ImportCommodity/  Accessed June 2021  
Seemüller, E; Marcone, C; Lauer, U; Ragozzino, A; Göschl, M (1998) Current status of molecular classification of the phytopla smas. Journal of Plant 
Pathology  80. 
Veerakone, S; Tang, J Z; Ward, L I; Liefting, L W; Perez -Egusquiza, Z; Lebas, B S M; Delmiglio, C; Fletcher, J D; Guy, P L (2015) A review of the plant virus, 
viroid, liberibacter and phytoplasma records for New Zealand.  Australasian Plant Pathology , 44(5): 463 –514. 
Winter, S; Shahraeen, N; Koerbler, M; Lesemann, D E (2006) Characterization of Tomato fruit yellow ring virus: a new Tospovir us species infecting tomato in 
Iran. Plant Pathology,  55(2): 287 –287. 
Zarzyńska -Nowak, A; Rymelska, N; Borodynko, N; Has iów-Jaroszewska, B (2016) The occurrence of Tomato yellow ring virus on tomato in Poland.  Plant 
Disease,  100(1): 234 –234. 
 
   
77 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Appendix 2.  Glossary  and Ab breviations  
 
Term or a bbreviation  Definition  
BRAD  Biosecurity Risk Analysis Database . MPI internal  database  that records the regulatory status and other 
information about plant pests.  
CMI Climate (or composite) match index , a value that indicates the similarities between a location overseas and 
New Zealand (Phillips et al. 2018).  
commercial production  Definition for the purposes of risk assessment: a  process/system where activities, such as in -field monitoring, 
in-field pest control activities, harvesting, cleaning, sorting and grading have been undertaken to produce a 
commodity that is free of defects such as broken skin, rot and damage. Depending on the systems in place, 
these activities can be undertaken at any stage from the point of planting to the point of export.  
commodity description  The commodity description defines the form of the commodity th at is covered by the IRA, e.g. the commodity 
species and the countries under consideration. The commodity description may also include commercial 
production and/or grading requirements or other commodity quality specifications.  
conditional non -host  Fruit or vegetable at a specified maturity and specified physical condition that cannot support the complete 
development of a particular pest species.  
CPC  Crop Protection Compendium . A CABI database  that provides information about crop pests.  
disease  A disorder of structure or function in a plant, especially one that affects a specific location and is not simply a 
direct result of physical injury.  
endemic  An animal, plant, pest, or disease that is native to and is not naturally found outside a defined geographical 
area.  
establishment  Perpetuation, for the foreseeable future, of an organism or disease within an area after entry.  
ERS Emerging Risk System , an MPI workflow  system that  allows MPI to  receive,  process and store information 
about new biosecur ity risks and to  manage those risks  in a timely fashion.  
exposure  The process of a hazard organism moving from the commodity it arrived on to another host (also called 
“transfer”).  
exotic  This word has different meanings in different fields, but in this document , it is defined as an animal, plant, pest 
or disease that is not indigenous to New  Zealand.  
hazard  A hazard is a pest (including arthropods and pathogens) or disease that is not present in the PRA area, e.g. 
New Zealand (or is present but still represents a biosecurity risk, e.g. is capable of vectoring pathogens not 
present in the PRA area), has the ability to establish and cause harm in the PRA area and is associated with 
the entry pathway (commodity/country of origin) under consideration.   
Biosecurity New Zealand   Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021   • 78 Term or a bbreviation  Definition  
indigenous  Native; organism originating or occurring naturally in a specified area.  
inspection  Official visual examination of plants, plant products or other regulated articles to determine if pests are present 
and/or to determine compliance with phytosanitary regulations (FAO 2012).  
introduced  Not indigenous, not native to the area in which it now occurs, having been brought into this area directly or 
indirectly by human activity.  
IPPC  International Plant Protection Convention, a 1951 multilater al treaty overseen by the Food and Agriculture 
Organization that aims to secure coordinated, effective action to prevent and to control the introduction and 
spread of pests of plants and plant products.  
ISPM  International Standards for Phytosanitary Measu res, international standard s adopted by the Conference of the 
Food and Agriculture Organization, the Interim Commission on phytosanitary measures or the Commission on 
phytosanitary measures, established under the IP PC. 
IHS Import Health Standard  (See “Import Health Standard” for a definition .) 
Import Health Standard  An import health standard (IHS) is a document issued under section 24A of the Biosecurity Act 1993. It states 
the requirements that must be met before risk goods can be imported into New Zealand.  
IRA Import Risk Analysis, an administrative process through which quarantine policy is developed or reviewed, 
incorporating risk assessment, risk management and risk communication.  
MPI Ministry for Primary Industries, New  Zealand  
non-host  Fruit or vegetable that will not support the complete development of a particular pest species regardless of the 
stage of maturity and physical characteristics.  
NPPO  National Plant Protection Organisation, official service established by a government to discha rge the functions 
specified by the IPPC.  
NZOR  New Zealand  Organisms Register , an actively maintained compilation of all organism names relevant to New 
Zealand: indigenous, endemic or exotic species or species not present in New Zealand but of national int erest . 
ONZPR  Official New Zealand Pest Register. MPI database  that records organisms that  may be associated with plants 
or plant products that are imported into New Zealand.  Plant and plant product importers can use ONZPR  to find 
out the quarantine status of a species – regulated or non -regulated.  
pest Any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products.  
pest-free area  An area in which a specific pest does not occur as demonstrated by scientific evidence and in which, where 
appropriate, this condition is being officially maintained.  
pest-free place of production  A place of production in which a specific pest does not occur as demonstrated by scientific evidence and i n 
which, where appropriate, this condition is being officially maintained for a defined period.   
79 • Tissue culture of  Alstroemeria spp. from India and South Africa  IRA, August 2021    Biosecurity New Zealand  Term or a bbreviation  Definition  
PFA Pest-free area (See “Pest -free area” for a definition .) 
PFPP  Pest-free place of production  (See “Pest -free place of production ” for a definition .) 
PPIN  Plant Pest Information Network database (MPI) , a record of organisms collected in New Zealand and identified 
by MPI’s Plant Health and Environment Laboratory.  
PRA  Pest Risk Assessment or Pest Risk Analysis  
QuanCargo  New Zealand border transaction databas e, detailing commercial consignments and interceptions of pests made 
by quarantine inspection (MPI).  
quarantine pest  A pest of potential economic importance to the area endangered thereby , e.g. New Zealand,  and not yet 
present there, or present but not wi dely distributed and being officially controlled . 
systems approach  The integration of different pest risk management measures, at least two of which act independently, and which 
cumulatively achieve the appropriate level of phytosanitary protection. Measures  can be undertaken at any 
stage from the point of planting to the point of export.  
vector  An organism or object that transfers a pest, parasite, pathogen or disease from one area or host to another.