PHYTOSANITARY PROCEDURES

Transcription

1 EPPO Standards PHYTOSANITARY PROCEDURES RUBUS VIRUSES INSPECTION AND TEST METHODS PM 3/31(1) English oepp eppo Organisation Européenne et Méditerranéenne pour la Protection des Plantes 1, rue Le Nôtre, Paris, France

2 APPROVAL EPPO Standards are approved by EPPO Council. The date of approval appears in each individual standard. REVIEW EPPO Standards are subject to periodic review and amendment. The next review date for this set of EPPO Standards is decided by the EPPO Working Party on Phytosanitary Regulations. AMENDMENT RECORD Amendments will be issued as necessary, numbered and dated. The dates of amendment appear in each individual standard (as appropriate). DISTRIBUTION EPPO Standards are distributed by the EPPO Secretariat to all EPPO member governments. Copies are available to any interested person under particular conditions upon request to the EPPO Secretariat. SCOPE EPPO Phytosanitary Procedures are intended to be used by National Plant Protection Organizations, in their capacity as bodies responsible for the inspection, testing and treatment of plants and plant products moving in trade, or for the implementation of surveys against quarantine pests. REFERENCES OEPP/EPPO (1996) Glossary of Phytosanitary Terms. EPPO Technical Documents no CABI/EPPO (1997) Quarantine Pests for Europe, 2nd edition (Ed. by Smith, I.M.; McNamara, D.G.; Scott, P.R.; Holderness, M.), CAB International, Wallingford, UK. OEPP/EPPO (in preparation) Specific Quarantine Requirements. Available as electronic documents from the EPPO Web Site. DEFINITIONS Phytosanitary procedure: Any officially prescribed method for performing inspections, tests, surveys or treatments in connection with plant quarantine. Inspection: Official visual examination of plants, plant products or other regulated articles to determine if pests are present and/or to determine compliance with phytosanitary regulations. Survey: An official procedure conducted over a defined period of time to determine the characteristics of a pest population or to determine which species occur in an area. Test: Official examination, other than visual, to determine if pests are present or to identify pests. Treatment: An officially authorized procedure for the killing, removal or rendering infertile of pests. 2

3 OUTLINE OF REQUIREMENTS EPPO Phytosanitary Procedures describe the methods to be followed for performing inspections, tests, or treatments of commodities moving in trade, or surveys against quarantine pests. For many quarantine pests, a reference to the relevant EPPO Phytosanitary Procedure is made in the corresponding EPPO Specific Quarantine Requirements. The development of EPPO phytosanitary procedures started many years ago, and these methods have been published in the Bulletin OEPP/EPPO Bulletin under several titles: Fumigation standards, Quarantine Inspection Procedures and Quarantine Procedures. All of them are now appearing under the title EPPO Phytosanitary Procedures and are being edited into EPPO Standard format. The numbering of these procedures will continue to follow the sequence described in the Bulletin OEPP/EPPO Bulletin 20(2), , which corresponds approximately to the chronological order of appearance of the Phytosanitary Procedures. 3

4 EUROPEAN AND MEDITERRANEAN PLANT PROTECTION ORGANIZATION ORGANISATION EUROPEENNE ET MEDITERRANEENNE POUR LA PROTECTION DES PLANTES PM 3/31(1) English Phytosanitary procedure RUBUS VIRUSES INSPECTION AND TEST METHODS Specific scope This standard describes the inspection and test methods for Rubus viruses, to satisfy the requirements of EPPO Standards PM 2/31(2), PM 2/102(2), PM 2/147(2), PM 2/148(2), PM 2/149(2). Specific approval and amendment First approved in September Edited as EPPO Standard in Introduction The EPPO A1 and A2 quarantine lists include several important viruses of Rubus. Details about their biology, distribution and economic importance can be found in the specific Data sheets. Raspberry leaf curl luteovirus (RLCV) (A1 list) infects only Rubus (Data sheet no. 31; OEPP/EPPO, 1978). Raspberry ringspot nepovirus (RRV) (A2 list) causes ringspot and yellow blotch in Rubus (Data sheet no. 98; OEPP/EPPO, 1983). Tomato ringspot nepovirus (TomRSV) (A2 list) causes decline, crumbly berry and yellow blotch curl in Rubus (Data sheet no. 102; OEPP/EPPO, 1982). Finally, several viruses are reported pollen-borne in Rubus outside the EPPO region, but have yet to be found in Rubus within the region (Data sheet no ; OEPP/EPPO, 1986): apple mosaic ilarvirus (ApMV), cherry leaf roll nepovirus (CLRV) and tobacco streak ilarvirus (black raspberry latent strain) (BRLV). According to the EPPO Specific quarantine requirements (OEPP/EPPO, 1990) for Rubus viruses, plants for planting (except seeds) of Rubus have to come from a field inspected for the viruses concerned (according to the origin of the plants and the regulations of the importing country) and found free from these viruses. If they come from a country where the viruses occur in Rubus, they have to be derived (not further than the third generation) from mother plants tested for the viruses, and maintained under conditions designed to prevent reinfection. In addition, the viruses (except RLCV) are seed-transmissible in Rubus, so Rubus seeds and seedlings have also to be derived from such plants. It should, however, be noted that the A2 nepoviruses RRV and TomRSV can be covered by regular nuclear stock certification of Rubus and Ribes within EPPO countries, together with other viruses which are not listed as quarantine pests. Accordingly, the relevant inspections and tests for them can be found in the EPPO certification scheme for Ribes and Rubus (OEPP/EPPO, 1992). Besides, it may be useful, for TomRSV, to refer to the Quarantine procedure no. 32 for tomato ringspot nepovirus in fruit trees and grapevine (OEPP/ EPPO, 1991), whose test methods can readily be extended to Ribes and Rubus. In consequence, this Quarantine procedure essentially refers to the A1 virus RLCV, and to the three pollen-borne viruses which do not occur in Rubus in the EPPO region. Accordingly, its use only concerns Rubus imported into EPPO countries from outside the EPPO region. 4

5 Methods Visual inspection is relevant for RLCV and CLRV, which can be expected to cause symptoms in Rubus, but not for the ilarviruses, which tend to be latent (causing loss of vigour and interacting with other viruses). Nepoviruses and ilarviruses can be detected either by sap inoculation to herbaceous indicators or by ELISA. The former is simple but requires up to 1-3 weeks for symptoms to appear. The latter is probably the most reliable and sensitive, but is strain-specific so that the test has to be done with a suitable broad-spectrum antiserum, or combination of individual antisera. For RLCV, the only test method is graft inoculation of a woody indicator. See Appendix I for details of the methods. APPENDIX I Visual inspection RLCV causes curling and yellowing of leaves of Rubus idaeus, shortening of laterals and proliferation of shoots to form a rosette. New canes are stunted and branched. Infected plants generally die within 2 years. CRLV causes stunting of the plant, dwarfing and distortion of the leaves of fruiting canes, with line-pattern, chlorotic mottling or ringspots on some leaves. These symptoms are not very distinct from those caused by other nepoviruses, so cannot be used diagnostically. Transmission to herbaceous indicators CRLV, ApMV, BRLV (and indeed TSV in general) can be transmitted by inoculation of sap to herbaceous test plants and can usually be detected in this way. Grind rapidly growing leaves from Rubus plants to be tested in a small volume of 2%, nicotine solution with a little celite as abrasive. Gently rub this sap extract on leaves of young, soft, rapidly growing plants of Chenopodium quinoa and/or Cucumis sativus. Keep test plants in aphid-proof glasshouses at about 20 C and observe for symptoms over about 3 weeks, Symptoms caused by these viruses in inoculated leaves should be apparent in 4-10 days. BRLV and ApMV are probably best detected in very young cucumber cotyledons, but all viruses should induce symptoms in C. quinoa. All four viruses should become systemic in C. quinoa, but some strains of tobacco streak virus (BRLV is a strain of TSV) are not systemic in this host. Woody indicators While the nepoviruses and ilarviruses could be detected by grafting Rubus to woody indicators, there is no purpose in doing so for the alternative methods are much superior. In the case of RLCV, however, this is the only method of detection. Graft scions of test Rubus plants to Rubus phoenicolasius (wineberry) which develops particularly severe symptoms. In 5

6 general, R. idaeus can also be used. Symptoms may take 2-12 months to appear after graft inoculation. The two strains of RLCV (alpha and beta) are both detected. ELISA and other serological methods CRLV, ApMV, BRLV (and TSV) can all most readily be detected by serological tests, and their identity can be determined unequivocally only by such tests. Many serological variants of BRLV, CLRV and ApMV occur and antiserum that reacts to a wide spectrum of variants and/or antisera to several different virus isolates should be used. At certain times of the year, the concentration of BRLV and ApMV in herbaceous test plants may be too low to give a visible reaction in agar gel double-diffusion serological tests. Thus, ELISA is the method to be preferred. It may be used either on herbaceous indicator plants or on Rubus sap. It is probably more reliable for detecting TSV, CRLV and ApMV in Rubus sap than is infectivity assay. For details on the methodology, refer to EPPO Quarantine procedure no. 32 for tomato ringspot nepovirus in fruit trees and grapevine (OEPP/EPPO, 1991). References OEPP/EPPO (1978) Data sheet on quarantine organisms no. 31: raspberry leaf curl virus. Bulletin OEPP/EPPO Bulletin 8 (2). OEPP/EPPO (1982) Data sheet on quarantine organisms no. 102: tomato ringspot virus. Bulletin OEPP/EPPO Bulletin 12 (1). OEPP/EPPO (1983) Data sheet on quarantine organisms no. 98: raspberry ringspot virus. Bulletin OEPP/EPPO Bulletin 13 (1). OEPP/EPPO (1986) Data sheet on quarantine organisms no : pollen-borne viruses in Rubus. Bulletin OEPP/EPPO Bulletin 16, OEPP/EPPO (1990) Specific quarantine requirements. EPPO Technical Documents no OEPP/EPPO (1991) Quarantine procedures no. 32: tomato ringspot nepovirus in fruit trees and grapevine. Bulletin OEPP/EPPO Bulletin 21, OEPP/EPPO (1992) Scheme for the production of certified pathogen-tested Ribes and Rubus. Bulletin OEPP/EPPO Bulletin 22 (in preparation). Enquiries May be directed to: T. Jones, SCRI, Invergowrie, Dundee (GB). 6