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Justification for qualification based on EPPO PM 4 Standards
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NAME OF THE ORGANISM: Ophiovirus vaccinii (blueberry mosaic associated virus) (BLMAV0)

GENERAL INFORMATION ON THE PEST

Name as submitted in the project specification (if different):

Blueberry mosaic associated virus

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: Fruits (including hops) sector

If necessary, please list the species:

Is it justified that the pest is listed at a taxonomic rank below species level?

Not relevant

Conclusion:

Candidate: Fruits (including hops) sector

Justification (if necessary):

Note on taxonomy: Blueberry mosaic disease was associated with the presence of a novel ophiovirus, blueberry mosaic-associated virus (Ophiovirus vaccinii, BlMaV) (Thekke-Veetil et al, 2014). Thirty-five symptomatic plants all contained the virus, but so did 2 asymptomatic plants. There is no report of a biological demonstration of the relationship between virus and symptom. It is likely that BlMaV can be considered a causal agent of blueberry mosaic disease, in the tested plant no other recognizable/potential causal viruses were detected using NGS. Therefore, based on Thekke-Veetil et al (2014) and other publications since then (Thekke-Veetil et al., 2015; Jevremović et al., 2015, 2020; Cieślińska, 2020; Menzel et al., 2021; Çağlayan et al., 2021; Sands et al., 2021), blueberry mosaic associated virus should be considered to be the preferred name of the recognized disease, although Koch’s postulates still need to be fulfilled.

2 – Status in the EU:

Is this pest already a quarantine pest for the whole EU?

Presence in the EU:

Yes

List of countries (EPPO Global Database):

Conclusion:

Justification (if necessary):

Blueberry mosaic-associated virus (BlMaV) has been reported from Germany (Menzel et al., 2021), Netherlands (Anonymous, 2023), Poland (Cieślińska, 2020), Slovenia (Thekke-Veetil et al., 2015)

HOST PLANT N°1: Vaccinium (1VACG) for the Fruits (including hops) sector.

Origin of the listing:

Commission Implementing Directive (EU) 2014/98/EU and Commission Implementing Regulation (EU) 2019/2072

Plants for planting:

Plants intended for planting

3 - Is the pest already listed in a PM4 standard on the concerned host plant?

Yes

Conclusion:

Evaluation continues

Justification (if necessary):

EPPO Standard PM 4-18 Certification scheme for Vaccinium recommends testing for 'Blueberry mosaic agent'. Although the pest is considered listed in EPPO PM 4 Standard, additional data was collected when checking elements of taxonomy. The Fruit SEWG recommended to reassess the potential economic impact of this pest.
Although PL considered in responses to the questionnaire that plants for planting was not the main pathway, this was not supported by enough justification, and not supported by experts.

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:

Ophiovirus vaccinii (Blueberry mosaic-associated virus, BlMaV) has a limited host range, it has been reported in cultivated highbush blueberry, Vaccinium corymbosum and lowbush blueberry (Vaccinium pallidum) (Ramsdell & Stretch, 1987) and in wild V. corymbosum (Saad et al., 2021). Experimentally it can also be transferred to lettuce (Sands et al., 2017; Çağlayan et al., 2021).
BlMaV is spread locally by Olpidium virulentus (Sands et al., 2017; Çağlayan et al., 2021).
The virus is also spread with infected Vaccinium material.

5 - Economic impact:

Are there documented reports of any economic impact on the host?

Justification:

The virus is linked to mosaic symptoms on the leaves (e.g. Menzel et al., 2021). There are no reports on reduced harvests (Jevremović et al., 2020).

Sapkota et al (2024) studied incidence of black raspberry necrosis virus (BRNV), raspberry leaf mottle virus (RLMV), raspberry vein chlorosis virus (RVCV), and Rubus yellow net virus (RYNV) in raspberry plants. It provides interesting information that BRNV was identified in Norway as the most prevalent virus across all year, constituting 93% of total infected samples, and with the highest incidence as single infections (41% of all leaf samples). Mosaic and vein clearing symptoms were observed on most leaf samples with BRNV single infection, while some others had no clear symptoms. Heavily BRNV-infected raspberry cv. Glen Ample showed reduced plant vigor. However, transmission of BRNV to virus-free Glen Ample plants to induce similar symptoms should be further pursued. Mixed infection with other viruses exhibited more intense symptoms.

The Fruit SEWG commented that information from Sapkota et al (2024) mainly relates to symptoms, not impact, except for one cultivar. Glen Ample is known as a cultivar very sentitive to viruses. Testing in a crop with specific primers for a specific list of viruses is interesting but does not provide enough justification.

What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)

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?

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?

Conclusion:

Not candidate

Justification:

To early to tell, but BlMaV is probably already in Europe for a long time. So far it has only been reported from Vaccinium corymbosum. In experimentally infected lettuce no obvious symptoms were observed (Çağlayan et al., 2021).

6 - Are there feasible and effective measures available to prevent the presence of the pest on the plants for planting at an incidence above a certain threshold (including zero) to avoid an unacceptable economic impact as regards the relevant host plants?

Yes

Conclusion:

Justification:

The use of virus-tested propagation material.

7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?

Conclusion:

Justification:

CONCLUSION ON THE STATUS:

Disqualified: no reports of impact on production or harvest.

8 - Tolerance level:

Is there a need to change the Tolerance level:

Yes

Proposed Tolerance levels:

Delisting

9 - Risk management measures:

Is there a need to change the Risk management measure:

Yes

Proposed Risk management measure:

Delisting

REFERENCES:

Anonymous (2023) Blueberry mosaic associated virus herkennen (Naktuinbouw hand-out). https://www.nvwa.nl/documenten/plant/plantenpaspoort/opa/publicaties/blueberry-mosaic-associated-virus
Çağlayan K, Akkan R, Gazel M & Tok FM (2021). First report of the Olpidium virulentus–mediated transmission of blueberry mosaic‑associated virus in blueberries in Turkey. Journal of Plant Pathology 103, 1349. https://doi.org/10.1007/s42161-021-00918-x
Jevremović D, Leposavić,A & Paunović S (2015). First report of blueberry mosaic-associated virus in highbush blueberry in Serbia. Journal of Plant Pathology 97(3), 541.
Jevremović D, Paunović SA & Leposavić A (2020). Influence of blueberry mosaic associated virus on some
fruit traits of highbush blueberry ‘Duke’. Journal of Mountain Agriculture on the Balkans 23(3), 195-203.
Menzel W, Knierim D, Margaria P, Winter S, Entrop AP, Stremer P & Heupel M (2021) First report of Blueberry mosaic associated virus associated with mosaic symptoms of blueberry in Germany. New Disease Reports 44(2), e12051. https://bsppjournals.onlinelibrary.wiley.com/doi/full/10.1002/ndr2.12051
Ramsdell DC & Stretch AW (1987) Blueberry mosaic. In Virus Disease of Small Fruits (ed Converse RH). US Department of Agriculture, Agricultural Research Service pp. 119-120.
Saad N, Olmstead JW, Varsani A, Polston JE, Jones JB, Folimonova SY & Harmon PF (2021) Discovery of known and novel viruses in wild and cultivated blueberry in Florida through viral metagenomic approaches. Viruses 13(6), 1165. https://doi.org/10.3390/v13061165
Sapkota B, Trandem N, Fránová J, Koloniuk I, Blystad DR & Hamborg Z (2024) Incidence of aphid-transmitted viruses in raspberry and raspberry aphids in Norway and experiments on aphid transmission of black raspberry necrosis virus. Frontiers in Plant Science 15, 1441145.
Shands AC, Crandall SG & Miles TD (2017). First report of the ability of Olpidium virulentus to vector blueberry mosaic associated virus (BlMaV) on southern highbush blueberry in California. Plant Disease 101(9), 1683.
Thekke-Veetil T, Ho T, Keller KE, Martin RR & Tzanetakis IE (2014) A new ophiovirus is associated with blueberry mosaic disease. Virus Research 189, 92-96.
Thekke-Veetil T, Polashock JJ, Marn MV, Plesko IM, Schilder AC, Keller KE, Martin RR & Tzanetakis IE (2015) Population structure of blueberry mosaic associated virus: Evidence of reassortment in geographically distinct isolates. Virus Research 201, 79-84.