10 November  2023 
 
 
Kia ora,  
Subject:  Proposed changes to MPI-Accepted methods for testing for Diaporthe vaccinii  of cuttings and 
tissue culture  Vaccinium  species . 
The Ministry for Primary Industries (MPI) invites feedback on proposed changes to the current Vaccinium  
cuttings  and tissue culture (in -vitro)  import requirements in  the import health standard  155.02.06: Importation 
of Nursery Stock  (IHS). The proposed changes will allow for the use of a more rapid and efficient polymerase 
chain reaction (PCR) assay  to test for the presence of Diaporthe vaccinii  in imported nursery stock under the 
Vaccinium  schedule in th e IHS.  
 
You are being contact ed as a stakeholder with an interest in this matter and are invited to comment on the 
following proposed change : 
 
• Amendment of the current onshore testing methods to include the use of a rapid PCR testing  assay  for 
Diaporthe vaccinii as a requirement under  Vaccinium  schedule of conditions in the Nursery Stock 
standard .  
 
MPI’s assessment for the inclusion of the rapid PCR test is included in Appendix 1  of this letter . The p roposed 
amendment to the corresponding sched ule of special conditions in the Nursery Stock standard are included in 
Appendi x 2 of this letter.  
 
If you want to comment on the proposed amendment, please do so by 5pm on Friday , 24 November  2023. 
Any questions and all submissions should be directed to PlantImports@mpi.govt.nz . 
 
Yours sincerely,  
 
 
 
Ben Pocock  
Manager Plant Germplasm Team  
Animal and Plant Health  Directorate  
Biosecurity New Zealand  
 
 
Appendix 1 – MPI’s a ssessment for the rapid PCR assay test  for Diaporthe vaccinii  of cuttings and 
tissue culture of approved Vaccinium  species.   
Background  
1. The Ministry of Primary Industries Plant Health and Environment Laboratory (PHEL) ha s developed 
and optimised  a real-time polymerase  chain reaction (PCR) assay for the detection of the regulated 
pathogen Diaporthe vaccinii  on imported Vaccinium  nursery stock imported under the Vaccinium  
schedule of import health standard (IHS) 155.02.06: Importation of Nursery Stock .  
2. The purpose for developing the optimised PCR test was to have an alternative testing method for the 
detection of Diaporthe vaccinii  that is more rapid and efficient  than the current plating test option.  
3. The risk of Diaporthe vaccinii  on Vaccinium  nursery stock is currently managed with plating onto 
suitable isolation medium  to detect the pathogen on plants in post entry quarantine ( PEQ ), as 
specifi ed in the Vaccinium  schedule of the import health standard (IHS) 155.02.06: Importation of 
Nursery Stock .  
4. The development and optimisation of this PCR test has resulted in a rapid and efficient alternative test 
for Diaporthe vaccinii , which has been described in the Journal of Phytopathology , a peer-reviewed 
publication within the international scientific comm unity (Dharmaraj, K, et al, 2022).  
 
Purpose  
1. MPI proposes to include  the new  rapid PCR test assay as an alternative test method to manage the 
risk of Diaporthe vaccinii  on imported Vaccinium  nursery -stock.  
 
Assessment  
1. The development of the PCR assay test has resulted in a test that is: 
- specific to Diporthe vaccinii , no amplification was observed when the assay was tested against 82 
isolates of non -target species,  
- able to  detect the pathogen  in both symptomatic and non -symptomatic plant material , 
- able to detect the pathogen in low concentrations, even when diluted ten -fold. 
- has been performed consistently between different laboratories, and the paper has been  peer 
review ed within the international scientific community.  
2. The benefits of the PCR assay test compared with the current plating option are: 
- The PCR test results are available within 1-2 days compared with 2 -3 weeks  for plating . 
- The PCR test is a h ighly specific test  for D. vaccinii  only, while  plating has the possibility that fast-
growing  endophytes or secondary organisms could overgrow Diaporthe  colonies leading to the 
pathogen being undetected.  
- PCR testing allow s bulking of samples , thus  reducing the cost per sample test, versus plating 
which does not . 
- The extracted DNA sample used in the PCR test can also be used for other pathogens ( e.g. 
Monilia vaccinii -corymbosii ), further reducing costs for the importer and  creating efficiencies for 
the lab oratory . 
 Details of proposed change  
1. MPI proposes to add the PCR test for Diaporthe vaccinii  an alternative method for the testing and 
detection of the pathogen , in the ‘Inspection, Testing & Treatment  Requirements  for Vaccinium ' (see 
draft proposal appendix 2)  of the Vaccinium  schedule of the import Health Standard (IHS) 155.02.06: 
Importation of Nursery Stock . 
2. This change does not re place  the current plating  option for testing for Diaporthe vaccinii . It provides an 
additional testing option  under the Vaccinium  schedule . 
3. This proposed change does not affect the current Vaccinium macrocarpon schedule of the import 
Health Standard (IHS) 155.02.06: Importation of Nursery Stock . 
 
References  
Dharmaraj, K., Michalecka, M., Alexander, B. J. R ., & Toome -Heller, M. (2022). New real -time PCR assay for 
detecting the blueberry and cranberry twig blight pathogen, Journal of Phytopathology , 170, 683 -692 
https://doi.org/10.1111/jph.131.32    
 
Ministry for Primary Industries Standard 152.02.06 : Importation of Nursery Stock   
https://www.mpi.govt.nz/dmsdocument/1152 -nursery -stock -import-health -standard    
(page 322 -331 Vaccinium schedule)  
 Appendix  2 – Draft Vaccinium schedule  Inspection, Testing and Treatment Requirements for 
Vaccinium of the Nursery Stock standard