IDENTIFICATION OF BIOVARS AND RACES OF PSEUDOMONAS-SOLANACEARUM AND SOURCES OF RESISTANCE IN TOMATO IN NEPAL

Twenty-five strains of Pseudomonas solanacearum isolated from plants in Nepal were characterized by physiological and biochemical tests and by pathogenicity on seven hosts. Based on Hayward's classification scheme, eight strains were biovar II and 17 strains were biovar III. Results of pathogenicity tests showed that eight strains were race 3 and 17 were race 1. This is the first report of biovar III and race 1 in Nepal. Fifteen tomato cultivars were screened for resistance to P. solanacearum (race 1) in a greenhouse test. Incubation period, number of days required to reach 10% wilting, and average percentage of wilting were used as components of disease resistance. Four of the cultivars tested were susceptible, six were moderately susceptible, three were moderately resistant, and two were resistant. The cultivars CL1131 and Rampur small had longer incubation periods, a longer time to reach 10% wilting, and a lower average percentage of wilting than the other cultivars. These two cultivars may be sources of resistance to P. solanacearum in tomato in Nepal.