ASSESSING 6 AUSTRIAN POTATO CULTIVARS FOR RESISTANCE TO ERWINIA-CAROTOVORA SUBSP ATROSEPTICA

The susceptibility of six new Austrian cultivars to soft rot, stem rot and blackleg caused by Erwinia carotovora subsp. atroseptica was assessed over 2 years in two locations. Soft rot susceptibility was assessed by whole tuber and half tuber tests, stem rot by stem inoculation and blackleg by planting inoculated tubers in the glasshouse. The susceptibility of the cultivars tested with the tuber and blackleg test methods were in general agreement. The half tuber test was more precise in differentiating intermediate levels of susceptibility than the whole tuber test. The reaction of the cultivars to soft rot could be classified as susceptible (Gina and Romina), moderately susceptible (Ditta, Sonja and Bintje), or slightly susceptible (Treff, Komet and Desiree). Results from the stem rot test did not agree with this classification and also depended upon the physiological state of plants as influenced by growing season and glasshouse conditions.