NAME OF THE ORGANISM: Citrus exocortis viroid CEVD00

GENERAL INFORMATION ON THE PEST

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

exocortis

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: Ornamental 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: Ornamental sector

Justification (if necessary):

Overall, methods for reliable detection and identification/discrimination of pospiviroids are available, although their high sensitivity implies the risk of false-positive reactions because of cross-contamination. These techniques are already widely used by EU MS as indicated by the answers received to the questionnaire sent by EFSA (EFSA PLH, 2011).

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):

Austria (2010); Belgium (2014); Cyprus (2011); Czech Republic (2010); France (1979); France/Corse (1994); Germany (2008); Greece (2013); Italy (2011); Italy/Sicilia (1994); Italy/Sardegna (1994); Netherlands (2008); Portugal (2006); Slovenia (2011); Spain (1979)

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: Citrus (1CIDG) for the Ornamental sector.

Origin of the listing:

Commission Directive 93/49/EEC

Plants for planting:

Plants intended for planting

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

Yes

Conclusion:

Qualified

Justification (if necessary):

It is not specified in EPPO PM 4/12 Standard that the certification scheme does not apply for ornamental Citrus.

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:

Citrus spp. is a major host for CEVd (EFSA, 2011). The two most important means of spread are mechanical transmission and plant for planting (except seeds). Two other means of spread are, seed- and pollen- transmission, and insect transmission, and need to be considered although they are less important (EPPO, 2016). If CEVd is present on the plants for planting (including seeds), this will be considered to be the main pathway.

5 - Economic impact:

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

Yes

Justification:

Citrus exocortis viroid (CEVd) is a well-known pathogen present worldwide in citrus growing areas. It is the causal agent of the exocortis disease which causes stunting and bark scaling symptoms in trifoliate orange (Poncirus trifoliata), the citrange hybrids (Poncirus trifoliata × Citrus sinensis) and Rangpur lime (Citrus limonia), all of them widely used as rootstocks in commercial citrus orchards. Scaling symptoms begin at the soil level or even below the soil level and develop only 4-5 years after infection. Therefore, symptoms of CEVd may be overlooked. CEVd also infects other tolerant citrus species used as scion or rootstock, without causing any symptoms (EFSA, 2008).

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:

Justification:

Symptom severity, the time required for symptoms to appear, and whether they occur on the rootstock or scion depend on the CEVd strain involved, the age of the tree at the time of infection, and environnemental conditions (Compendium of Citrus Diseases). EFSA Panel on plant health (EFSA PLH, 2008) considered that direct effects of CEVd on Citrus could be fairly serious, but considered that a significant level of uncertainty is attached to this rating. The Panel stresses that this qualification applies only to sensitive citrus species and not to tolerant ones.

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:

Recommended for listing as an RNQP, based on EPPO PM 4 Standard.

8 - Tolerance level:

Is there a need to change the Tolerance level:

Yes

Proposed Tolerance levels:

Zero tolerance, based on visual examination (Experts recommended extrapolating the measures from the fruit Marketing Directive).

9 - Risk management measures:

Is there a need to change the Risk management measure:

Yes

Proposed Risk management measure:

(A) Derived from mother plants which have been inspected and found free from the pest;
AND
(B) Site of production found free from the pest over the last complete growing season by visual inspection of the plants at the appropriate time.

Justification (if necessary):

Experts considered that the Pest free area option is not reliable because of the risk linked to ornamentals sold all year long in the area.

REFERENCES:

EFSA Panel on Plant Health (PLH) (2011) Scientific Opinion on the assessment of the risk of solanaceous pospiviroids for the EU territory and the identification and evaluation of risk management options. EFSA Journal 9, 2330. Available online: www.efsa.europa.eu/efsajournal.htm;
EFSA Panel on Plant Health (PLH) (2008) Scientific Opinion of the Panel on Plant Heath on a request from the European Commission on Pest risk assessment made by France on Citrus exocortis viroid (CEVd) considered by France as harmful in French overseas department of Réunion. The EFSA Journal 685, 1-17;