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First Report of the Occurrence of Potato Wart Disease Caused by Synchytrium endobioticum in Turkey

Potato wart caused by Synchytrium endobioticum (Schilberszky) Pervical was observed in Turkey on different cultivars (Agria, Granola, Marabel, Marfona, Russet Burbank and Van Gogh) during the 2004 harvest season in the Misli (Bud) Plain where approximately 40,000 ha of potatoes are grown. This plain, lying between Nigde and Nevsehir provinces in the central-eastern Anatolia Region, has a predominance of sandy soils (60 to 80% sand) and climatic conditions suitable for production that has been a long-term monoculture using heavy fertilization with nitrogen (500 to 1,500 kg of N per ha) and phosphorus (200 to 500 kg of P₂O₅ per ha). The wart symptoms were observed on tubers but not on roots and stems. The warts were white, almost spherical, and softer in texture than the tuber tissue. Resting sporangia, observed within the fresh wart tissue using light microscopy, were light brown, spherical to ovoid and 50 to 70 μm in diameter. Soil surveys confirmed that resting sporangia were present in the fields where wart was observed. Resting sporangia were isolated from infected tubers and surrounding soil (2). An average of <1 sporangium per gram of soil was detected in the infested fields. Pathogenicity of the causal agent was demonstrated on 10 tubers of potato cv. Granola. Sprouts on the tubers were cut off at 2 mm above the tuber surface, the eye fields were ringed with warm vaseline using a sterile syringe without a needle and then inoculated by placing fresh cauliflower-like warts containing summer sporangia in the vaseline wells. The tubers were first incubated at 8 to 12°C for 48 h in the dark and after removing the wart tissue, placed in moist peat at 18°C and kept in an 8-h lighting period per day as described by Glynne-Lemmarzalh (1). Sporangia were reisolated from the white, fresh wart tissues observed 8 to 10 weeks later on the inoculated tubers. Two tubers inoculated with sterile tap water did not develop warts. Koch's postulates were fulfilled. Currently, approximately 20,000 ha of the Misli Plain are under official quarantine due to the finding of potato wart. Because of the large-scale occurrence in 2004, it is suspected that the pathogen entered Turkey 3 to 4 years earlier through importation of seed potato tubers from European countries. To our knowledge, this is the first report of the occurrence of wart on potatoes grown in Turkey. The importance of this occurrence in the middle of an area where 50% of Turkey potatoes are produced is duly noted.

References: (1) European and Mediterranean Plant Protection Organization. OEPP/EPPO Bull. 34:213, 2004. (2) M. C. Hampson and P. R. Thompson. Plant Soil 46:659, 1977.