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Justification for qualification based on EPPO PM 4 Standards
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NAME OF THE ORGANISM: Closterovirus macularubi (raspberry leaf mottle virus) (RLMV00)

GENERAL INFORMATION ON THE PEST

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

Raspberry leaf mottle 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:

Not evaluated: Fruits (including hops) sector

Justification (if necessary):

Note on taxonomy: Raspberry leaf spot virus (RLSV), Raspberry leaf mottle virus (RLMV) and Raspberry mottle virus (RMoV) are components of the Raspberry mosaic disease (RMD) (McGavin et al., 2010). These three viruses are highly similar and therefore, McGavin et al. (2010) propose to reclassify RLSV and RMoV as isolates of RLMV. RLMV is a closterovirus and was the first one described of these three viruses. Conclusion: raspberry leaf mottle virus would be the preferred name (new binomial name: Closterovirus macularubi).

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:

Candidate

Justification (if necessary):

RLMV has been reported in various countries in the EU e.g. Germany (CABI, 2023), Poland (Cieslinska, 2021), Romania (CABI, 2023); but also in Bosnia & Herzegovinia, Kazakhstan, Serbia and the United-Kingdom (CABI, 2023).

HOST PLANT N°1: Rubus (1RUBG) 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 4-10 Certification scheme for Rubus recommends testing for 'Raspberry leaf mottle disease'.
Although PL considered in responses to the questionnaire that plants for planting was not the main pathway, this was not supported by enough justification.
The Fruit SEWG recommended to further assess the relative importance of the pathways as well as the economic impact of this virus alone. Evaluation continues on these criteria.

4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):

Conclusion:

Candidate

Justification:

In Europe, the main vector of RLMV (and of BRNV and RYNV) is Amphorophora idaei (the large raspberry aphid), and five biotypes of this aphid have developed in response to deployment of a number of resistance genes in the breeding programs there. Several other Amphorophora spp. and Aulacorthum solani, Macrosiphum euphorbiae, Macrosiphum fragariae (synonym: Sitobion fragariae), Illinoia rubicola (synonyms: Masonaphis rubicola, Oestlundia rubicola), Myzus persicae and Myzus ornatus are capable of transmitting various viruses of the RMD complex in Europe and North America.
A crop starting from virus free material will be quite readily be infected by aphids from virus infected plants in the natural environment.
The Fruit SEWG supported that plants for planting was only a significant pathways compared to natural spread when production occurs under protected conditions.

5 - Economic impact:

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

Yes

Justification:

RLMV is part of the Raspberry mosaic disease (RMD). RMD is an overarching term used to describe a range of diseases caused by various combinations of different viruses that are each transmitted by aphids. In the scientific literature, RMD has been given various alternate names, including red raspberry mosaic, type b mosaic, green mottle mosaic, raspberry bushy dwarf, raspberry leaf mottle, raspberry leaf spot, raspberry mosaic I, veinbanding disease, and veinbanding mosaic; reflecting the range of leaf symptoms that are produced in different Rubus hosts with different virus combinations and under different environmental conditions. In North America, the disease can affect all cultivated Rubus spp., with black raspberry sustaining the most damage. RMD in Canada affected red raspberry and was found to be caused by co-infection with two viruses, Black raspberry necrosis virus (BRNV) and Rubus yellow net virus (RYNV). However, recent evidence suggests that Raspberry leaf mottle virus (RLMV) is very common there as well and is likely part of the virus complex causing the disease. In Europe, high percentage of co-infection occurrence of BRNV and RLMV are reported, both in raspberry plants and aphids (Sapkota et al., 2024). Red raspberry plants affected by RMD often were found to carry BRNV, RYNV, RLMV, and Raspberry leaf spot virus (RLSV), which is now known to be a strain of RLMV.

There is no evidence in literature on economic damage caused by RLMV single infections. Martin et al (2013) mention that RLMV and Raspberry leaf spot virus (RLSV) are reported to be widespread in the UK and cause latent (symptomless) infection in many red raspberry cultivars but to produce 'diagnostic' symptoms in a few cultivars.

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?

Conclusion:

Not candidate

Justification:

No data are available in literature on economic impact of this individual virus, alone.

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?

Conclusion:

Justification:

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: economic impact on its own considered acceptable. No clear relation of co-infection with other particular viruses. Plants for planting is not considered to be a significant pathway compared to natural spread of the complex by aphids under outdoor conditions.

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:

CABI (2023) Distribution maps of plant diseases. Map No. 1338. Edition 1. Raspberry leaf mottle virus. CABI Head Office, Wallingford, UK.
Cieslinska M (2021) Cieślińska, M., 2021. First report of raspberry leaf mottle virus infecting raspberry in Poland. Plant Disease 105(3) 714-714.
MacFarlane SA, Tzanetakis IE, Halgren AB & Martin RR (2017) Raspberry mosaic disease. In Compendium of raspberry and blackberry diseases and pest, 2nd edition (eds Martin RR, Ellis MA, Williamson B & Williams RN). American Phytopathological Society, St Paul MN, USA. Pages 75-78.
Martin RR, MacFarlane S, Sabanadzovic S, Quito D, Poudel B & Tzanetakis IE (2013) Viruses and Virus Diseases of Rubus. Plant Disease 97(2), 168-182. https://doi.org/10.1094/PDIS-04-12-0362-FE.
McGavin WJ & MacFarlane SA (2010) Sequence similarities between Raspberry leaf mottle virus, raspberry leaf spot virus and the closterovirus Raspberry mottle virus. Ann of Appl Biol 156 (2010) 439-448.
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.