Distribution of race 2 of fusarium oxysporum f. sp. lycopersici in tomato fields in Israel

Tomato fields of cultivars possessing I genes for resistance to race I of Fusarium oxysporum f. sp. lycopersici were surveyed in Israel during the years 1963-1973 for the appearance of race 2, to which they are not resistant. Race 2 was found throughout the investigated periods in a total of 49 locations in 31 settlements, on all cultivars, and in increasing incidence with time. In greenhouse tests race 2 isolates were pathogenic to i i and I cultivars but not to a cultivar resistant to race 2. A detailed study was carried out in the Tel Mond area where tomatoes are grown widely. In 1971/72, race 2 was detected in 11 out of 12 fields, and in 1972/73 in 10 out of 14 fields. Its occurrence was related to frequent tomato cropping. The implications of its spread are discussed.