The Viability of Winter Sporangia of Synchytrium endobioticum (Schilb.) Perc. from Poland

The longevity, infectivity and virulence of winter sporangia of Synchytrium endobioticum, the causal agent of potato wart disease, were studied in soil collected from an infested plot 43 years since the last observed infection. The demarcated plot was located in a mountainous area of the central part of Sudetes Mountain range in Poland and no potatoes were grown in the plots over that period. Sporangia of S. endobioticum were collected from the samples and retained viability after 46 years. Infectivity of the fungus was tested using modified Potoek's tube test. The ability of the spores to invade and replicate in potato host tissue was demonstrated using sporangia collected after 43 years. The virulence of the obtained isolates was tested with the Glynne-Lemmerzal method. Two different pathotypes were identified: 1(D1), the most widely distributed in Europe and 3(M1), a unique Polish local pathotype, which was isolated and identified for the first time from the same location in 1965.