Regulated non-quarantine pest Project

An EU funded project for the benefit of the whole EPPO region

NAME OF THE ORGANISM: Shallot latent virus (SLV000)


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?

Is the pest defined at the species level or lower?:

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

  • 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?

Presence in the EU:


Justification (if necessary):
This pest was dentified in the Netherlands and Denmark, but similar viruses were recorded from England and France. It probably occurs world-wide (Bos, 1982). The pest has also been seen in Belgium, Czech Republic, Greece and Italy during reference searches.

HOST PLANT N°1: Allium cepa Aggregatum types (Allium ascalonicum) (ALLAS) 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?
Evaluation continues

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

SLV may occur in combination with other viruses. The virus is transmissible in a non-persistent manner by Myzus ascalonicus and perhaps by Aphis fabae, but not by M. persicae (Bos 1982, Brunt et al., 1996) from other infected Allium crops or overwintered discarded plants. Material can be cleaned of infection by combining in vitro thermotherapy and meristem culture.
In conclusion, shallots are usually grown from bulbs and therefore infected bulbs are a pathway if not produced under secure-aphid free conditions. If cultivation, removal of discarded overwintering bulbs, debris and aphid control precautions have been effectively carried out in the surrounding area, plants for planting could be considered a significant pathway.

5 - Economic impact:

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

The virus occurs, apparently symptomlessly, in shallot (Allium cepa Aggregatum types), but virus-free plants were not available for comparison of infected with healthy plants (Bos, 1982). In Slovenia it was found in shallot plants with virus symptoms, together with OYDV but it was not clear if symptoms in different plants were caused by SLV alone or in combination with OYDV (Mavrič et al, 1999). In a publication it was found that SLV does not appear to exert any influence on the yield (Messiaen et al., 1993). In conclusion, SLV is not considered to have an economic impact in shallot in the absence of other Allium viruses.
It should be noted there are also some other viruses of shallot (Shallot mite-borne latent virus and Shallot virus X) which are not listed specifically by the directive.

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?

Not candidate

Experts concluded that Economic impact is considered acceptable.

Disqualified: economic impact is considered acceptable. The pest will be covered by the general 'substantially free from' requirement.

8 - Tolerance level:

Is there a need to change the Tolerance level:

Proposed Tolerance levels:
Not recommended for the RNQP status.

9 - Risk management measures:

Is there a need to change the Risk management measure:

Proposed Risk management measure:
Not recommended for the RNQP status.

  • Bos L (1982) Descriptions of plant Viruses. Shallot latent virus. Research Institute for Plant Protection, Wageningen, The Netherlands. Available at:;
  • Brunt AA, Crabtree K, Dallwitz M J, Gibbs A J, Watson L & Zurcher E J (1996 onwards) Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 16th January 1997. Available at:;
  • Mavrič I, Mirkovič V & Ravnikar M (1999) Virus infections of Allium. Zbornik predavanj in referatov 4. Slovenskega Posvetovanja o Varstvu Rastlin v Portorožu od 3. do 4. pp.45-50;
  • Messiaen JM, Leroux JP, Pichon M & Beyries A (1993) "les allium alimentaires reproduits par voie végétative" du labo au terrain. Edition INRA;