NAME OF THE ORGANISM: Onion yellow dwarf virus (OYDV00)
GENERAL INFORMATION ON THE PEST
Name as submitted in the project specification (if different to the preferred name):
Pest category:
Viruses and viroids
1- Identity of the pest/Level of taxonomic listing:
Is the organism clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?
Yes
Is the pest defined at the species level or lower?:
Yes
Can listing of the pest at a taxonomic level higher than species be supported by scientific reasons or can species be identified within the taxonomic rank which are the (main) pests of concern?
- Not relevant: Vegetable propagating and planting material (other than seeds) sector
Is it justified that the pest is listed at a taxonomic rank below species level?
Not relevant
Conclusion:
- Candidate: Vegetable propagating and planting material (other than seeds) sector
2 – Status in the EU:
Is this pest already a quarantine pest for the whole EU?
No
Presence in the EU:
Yes
List of countries (EPPO Global Database):
Austria (1993); Czech Republic (2011); Denmark (1984); Estonia (1984); Finland (2011); France (1984); Germany (1993); Hungary (1992); Poland (1984); Romania (1984); United Kingdom (1993); United Kingdom/England (1994); United Kingdom/Scotland (1994)
Conclusion:
candidate
Justification (if necessary):
Data of the presence of this pest on the EU territory are available in EPPO Global Database (https://gd.eppo.int/).
HOST PLANT N°1: Allium fistulosum (ALLFI) for the Vegetable propagating and planting material (other than seeds) sector.
Origin of the listing:
RNQP Questionnaire
Plants for planting:
Plants intended for planting
3 - Is the pest already listed in a PM4 standard on the concerned host plant?
No
Conclusion:
Evaluation continues
4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):
Yes
Conclusion:
Candidate
Justification:
OYDV is documented to occur in A. fistulosum. If initially infected, the virus would be spread by division multiplication into new plants and infection would also be transmissible during vegetative growth by any Myzus persicae present.
A fistulosum is also multiplied by micro propagation for elimination of viruses to obtain healthy plantlets, and also by normal true seedlings from seed-sown materials, however the latter would be free as the virus is not known to be transmissible through seeds. Therefore provided the last two categories are produced inside under aphid-proof conditions, seedlings for transplanting should be free of infection.
Plants for planting are therefore a pathway and if cultivation, removal of other inoculum sources and other precautions have been effectively carried out in the surrounding area, plants for planting as seedlings or divided plants could therefore be considered the main pathway.
A fistulosum is also multiplied by micro propagation for elimination of viruses to obtain healthy plantlets, and also by normal true seedlings from seed-sown materials, however the latter would be free as the virus is not known to be transmissible through seeds. Therefore provided the last two categories are produced inside under aphid-proof conditions, seedlings for transplanting should be free of infection.
Plants for planting are therefore a pathway and if cultivation, removal of other inoculum sources and other precautions have been effectively carried out in the surrounding area, plants for planting as seedlings or divided plants could therefore be considered the main pathway.
5 - Economic impact:
Are there documented reports of any economic impact on the host?
Yes
Justification:
Little information is available, however symptoms of mosaic and yellow streak striping, curling and distortion of flower stems were observed in natural infection of Welsh onion in Iran (Saffar et al., 2013). Yields in Japan of plants artificially infected with OYDV, GLV or both viruses in the field, were 85.2, 79.3 and 73.4% of healthy plants, respectively. OYDV infection induced leaf blight called Kasuri as well as mosaic symptoms on infected plants (Fukami & Ishii, 1991). This virus is often found in association with other viruses of Allium. However no unacceptable economic impact is observed on A. fistulosum (Messiaen et al., 1993).
What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)
Minimal
Is the economic impact due to the presence of the pest on the named host plant for planting, acceptable to the propagation and end user sectors concerned?
Yes
Is there unacceptable economic impact caused to other hosts (or the same host with a different intended use) produced at the same place of production due to the transfer of the pest from the named host plant for planting?
No
Conclusion:
Not candidate
Justification:
CONCLUSION ON THE STATUS:
Disqualified: acceptable economic impact. This pest/host combination will be covered by the substantially free from requirement.
8 - Tolerance level:
Is there a need to change the Tolerance level:
No
Proposed Tolerance levels:
Not recommended for the RNQP status.
9 - Risk management measures:
Is there a need to change the Risk management measure:
No
Proposed Risk management measure:
Not recommended for the RNQP status.
REFERENCES:
- Fukami M & Ishii K (1991) Occurrence of garlic latent virus (GLV) and onion yellow dwarf virus (OYDV) on seedless Welsh onions "Bozushirazu" in Chiba Prefecture, and influence of their infection on their yield. Bulletin of the Chiba Prefectural Agricultural Experiment Station 32, pp.9-17;
- Messiaen JM, Leroux JP, Pichon M & Beyries A (1993) "les allium alimentaires reproduits par voie végétative" du labo au terrain. Edition INRA;
- Saffar ZN, Torabi S, Naghavi M, Golnaraghi AR & Aryakia E (2013) Onion yellow dwarf virus on leek, onion, shallot and welsh onion in Iran. Journal of Plant Pathology 95, Supplement pp.S4.73;