Abstract
Fusarium wilt occurred in 1980 on the tomato cultivars Saturn, Kairyo-Toko, Flora, Topic, which were resistant to race 1 of the causal fungus Fusarium oxysporum f. sp. lycopersici, and had been grown in a greenhouse located in Orido and Miho, Shimizu in Shizuoka Prefecture. The causal organism was identified as F. oxysporum f. sp. lycopersici race J 2 on the bases of inoculation tests to tomato differential cultivars. Outbreak of the disease was recorded by 60-65 per cent of the tomato growers, and in the 1980 and 1981 seasons, of a total number of 340,000 and 150,000 tomato plants 3.6 and 4.7 per cent of the tomatoes became infected, respectively. The number of diseased plants increased from several to over 10 times as many as in the preceding year in spite of the application of chloropicrin in the fields. The first symptoms of Fusarium wilt appeared from late August to early November, mostly in early October.
