State Plant Health and Seed Inspection Service, Warsaw, Poland A LONG-TERM STRATEGY OF SHARKA ERADICATION IN POLAND. J. Żandarski and A.

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1 State Plant Health and Seed Inspection Service, Warsaw, Poland A LONG-TERM STRATEGY OF SHARKA ERADICATION IN POLAND J. Żandarski and A. Zych Key words: Plum pox virus, control, quarantine Introduction The sharka (plum pox) disease, caused by Plum pox virus (PPV), is a reason of serious losses in plum, peach and apricot crops. The disease was reported for the first time from Bulgaria (Atanasoff 1932). It has spread from Balkan countries throughout almost whole territory of Europe (Data sheets 1997). In spite of strict quarantine measures, PPV has been recently introduced to North America (Carter-Lane and Redding 1999, Ferguson and Prange 2000) and earlier to other areas of the world (inter alia Chile, Egypt, India, Syria, Turkey). Plum pox virus affects mainly plants from the genera of Prunus (Quarantine Procedure , Adams 1995, Data sheets 1997). From economical point of view, plum (Prunus domestica L.), peach (P. persica (L.) Batsch.), apricot (P. armeniaca L.) and almond (P. amygdalus Batsch) are the most important natural hosts of PPV. The strain of PPV, naturally infecting sour cherry (P. cerasus L.) was reported by Kalashyan et al. (1994) and a similar one was found in sweet cherry (Crescenzi et al., 1995). PPV was also detected in walnut trees (Juglans regia L.) located nearly infested plum orchards (Baumgartnerowa 1996). Foliar symptoms of the sharka disease consist mainly of pale green chlorotic spots, rings and lines that can be visible from early summer onward. The development of symptoms on fruits depends on cultivar mainly, but usually they consist of rings and blotches, which are best visible in fully expanded unripe fruit, as well as sunken rings and spots. Red rings and spots can occur on the stones. Affected fruits have lower sugar content and taste not good. A high percentage of the fruit usually drops from the tree prematurely. Phytopathol. Pol. 36: The Polish Phytopathological Society, Poznań 2005 ISSN

2 138 Short communications Occurrence of sharka in Poland In Poland, sharka was observed for the first time in 1961 on plum in southern part of the country (Szczygieł 1962), but it has spread to other regions and hosts (peach and apricot) with time. The extend and the prevalence of the sharka occurrence had not been precisely recognized until 1996, when the delimiting survey was carried out by The Plant Protection Inspection Service. That survey led to the conclusion that sharka occurred on the whole territory of Poland, also in some scions orchards and nurseries, although in various prevalence (Żandarski and Chodkowski 1999). Southern regions were the most affected ones. It became clear that strict measures were necessary for the containment and the eradication of sharka disease in Poland. General guidelines were: increase of the number of crops inspected and tested, unification of the procedures followed by the Inspection, obligatory testing of propagative material for the presence of latent infection, and strictly observed eradication. Official sharka eradication programme was developed in 1998 by Main Inspectorate of Plant Protection in co-operation with the Institute of Pomology and Floriculture at Skierniewice. It included eradication of sharka from propagative material used for planting (scions orchards, rootstocks crops and nurseries), and also from commercial orchards as well as other plants being potential PPV hosts (small orchards attached to homesteads, allotment gardens and wild sharka hosts), especially in the areas surrounding places of propagative material production. Description of the programme The programme is composed of two main activities: detection of disease/virus occurrence and eradication of infected plants. Basic measures concerning detection of the disease foci are: visual inspections, carried out at the time when the probability of the symptoms occurrence is the highest; laboratory testing conducted in case when sharka symptoms or signs of aphids feeding are visible; in case of scions orchards and nurseries laboratory tests conducted even if the symptoms are not present in order to detect possible latent infection. All scion orchards, rootstock plantations as well as nurseries, and all other susceptible crops surrounding those cultivated crops, are subjected to visual inspection. The number of other crops to be inspected depends on the resources available. It is assumed that at least 10% of commercial orchards are to be inspected every year. Samples are appropriately labeled and packed, and then sent to the laboratory. More than 30 laboratories of The State Plant Health and Seed Inspection Service (formerly: The Plant Protection Inspection Service) have been prepared for the detection and identification of PPV in plant material. ELISA test is the routine diagnostic method (Clark et al. 1976, Voller et al. 1976, Adams 1978,

3 Short communications 139 Malinowski and Zawadzka 1994). In addition, the detection of PPV using PCR is conducted in the Central Laboratory (Korschineck et al. 1991, Wetzel et al. 1991). Mechanical inoculation of Chenopodium foetidum Schrad. is used occasionally. The appropriate quarantine measures are undertaken in case of positive results of the laboratory tests. Rooting out and destroying infected plants is ordered. Particularly strict additional measures are obligatory in case of infection found in scion orchard, rootstock crop or nursery. In consequence, apart from removal of infected plants, it is prohibited to use any plant (or its part) from infected stock for further propagation until the crop is recognized as free from the disease, based on the results of tests of plants, which were not removed, conducted in the next season. Additional measures, e.g. spraying against aphids, are applied in each case to prevent/limit the disease spread. Detailed recommendations concerning frequency and completeness of testing, as well as eradication policy, depend on the status of plant material. Brief summary is given below. 1. Scion orchards: at least two inspections (the first one from the end of May to the end of June; the second one from the middle of August to the end of September); obligatory testing at the time of the first inspection, even if no symptoms are visible; later, sampling and laboratory testing only if symptoms typical of sharka or similar ones are found; rooting out each infected tree; prohibition of scion production for grafting in the year of disease detection. 2. Rootstock plantations: one inspection during the vegetation period; sampling and laboratory testing in case of detection of sharka symptoms or signs of aphids feeding; in case of sharka detection in a lot destroying all rootstocks. 3. Nurseries: at least two inspections (the first one from the end of May to the end of June; the second one from the middle of August to the end of September); obligatory testing at the time of the second inspection if no symptoms are visible (at least 10% of plants); sampling and laboratory testing in case of detection of sharka symptoms or signs of aphids feeding; rooting out each infected tree and two neighbouring trees; prohibition of selling trees until the crop is recognized free from the disease; when the rate of infection exceeds 2% destroying the whole lot; checking the scions source, if introduction of PPV with scions is suspected. 4. Commercial orchards: at least one inspection during the vegetation period; sampling and laboratory testing in case of sharka symptoms detection; rooting out each infected tree and further inspections of the crop.

4 140 Short communications 5. Small orchards, allotment gardens and wild sharka hosts: at least one inspection during the vegetation period; sampling and laboratory testing in case of sharka symptoms detection; rooting out each infected tree and further inspections. Results of the programme Although the complete evaluation of the program results can be performed after its further several years operation, some of benefits have been noticed already: sharka has been almost completely eradicated from scions orchards; the movement of the infected plant material as well as those originating from infested scions orchards and nurseries has been eliminated almost completely; the prevalence of PPV in nurseries and crops surrounding scions orchards and nurseries has been reduced; in areas of sharka s high prevalence, new commercial orchards are not established usually, or tolerant cultivars are used as well as longer distances from other hosts of PPV are usually kept. Literature Adams A.N., 1978: The detection of Plum pox virus in Prunus species by enzyme-linked immunosorbent assay (ELISA). Ann. Appl. Biol. 90: Adams A.N., 1995: Plum pox virus. In: Compendium of stone fruit diseases. APS Press, The American Phytopathological Society, St. Paul, MN, USA: 69. Atanasoff D., 1932: Sharka po slivie, edna nova virusova bolest. Jb. Univ. Sofia, Agron. Fak. 11: Baumgartnerova H., 1996: First findings of Plum pox virus in walnut trees (Juglans regia L.). Acta Virol. 40: Carter-Lane S., Redding J., 1999: Agriculture officials confirm Plum pox virus in Pennsylvania orchard. Clark M.F., Adams A.N., Thresh J.N., Casper R., 1976: The detection of Plum pox and other viruses by ELISA. Acta Hortic. 67: Crescenzi A., Nuzzaci M., Piazzolla P., Levy L., Hadidi A., 1995: Plum pox virus (PPV) in sweet cherry. Acta Hortic. (The Hague) 386: Data sheets on quarantine pests Plum pox potyvirus, In: Quarantine pests for Europe. Eds. I.M. Smith, D.G. McNamara, P.R. Scott, M. Holderness. CAB International, Wallingford, UK: Ferguson B., Prange K., 2000: Plum pox virus confirmed in Canada. Kalashyan Y.A., Bilkey N.D., Verderevskaya T.D., Rubina E.V., 1994: Plum pox potyvirus on sour cherry in Moldova. Bull. OEPP/EPPO 24: Korschineck I., Himmler G., Sagl R., Steinkellner H., Katinger H.W.D., 1991: A PCR membrane spot assay for the detection of Plum pox virus RNA in bark of infected trees. J. Virol. Methods 31: Malinowski T., Zawadzka B., Zastosowanie metody ELISA do wykrywania wirusów drzew owocowych możliwości i ograniczenia. In: XXXIII Ogólnopolska Konferencja Sadownicza, 30 sierpnia 1 września 1994, cz. I. Instytut Sadownictwa i Kwiaciarstwa, Skierniewice: Quarantine Procedure No. 43. Plum pox potyvirus inspection and test methods, Bull. OEPP/EPPO 22:

5 Short communications 141 Szczygieł A., Pojawienie się w Polsce groźnej choroby wirusowej szarki Prunus virus-7. Ochr. Rośl. 1 2: Voller A., Bartlett A., Bidwell D.E., Clark M.F., Adams A.N., The detection of viruses by enzyme-linked immunosorbent assay (ELISA). J. Gen. Virol. 33: Wetzel T., Candresse T., Ravelonandro M., Dunez J., A polymerase chain reaction assay adapted to Plum pox potyvirus detection. J. Virol. Methods 33: Żandarski J., Chodkowski A., Wykrywanie, rejestrowanie i zwalczanie ognisk wirusa ospowatości śliwy (Plum pox virus, PPV) w Polsce. In: Ogólnopolska Naukowa Konferencja Ochrony Roślin Sadowniczych, luty Instytut Sadownictwa i Kwiaciarstwa, Skierniewice: Authors address: Jacek Żandarski, M.Sc., Adam Zych, M.Sc., State Plant Health and Seed Inspection Service, Main Inspectorate, ul. Wspólna 30, Warszawa, Poland gi@piorin.gov.pl; cl-tor@piorin.gov.pl Accepted for publication:

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