Fusarium oxysporum f. sp. niveum Race 2: A Highly Aggressive Race New to the United States. R. D. Martyn, Associate Professor, Department of Plant Pathology and Microbiology and Texas Agricultural Experiment Station, Texas A&M University, College Station 77843. Plant Dis. 71:233-236. Accepted for publication 29 September 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0233.

In 1981, an isolate of Fusarium oxysporum f. sp. niveum was isolated from a wilted watermelon plant in south central Texas that was highly aggressive toward several highly wilt-resistant watermelon cultivars. A second highly aggressive isolate was obtained in 1984 from the seed coat of a commercial lot of hybrid watermelon seed grown in north central Texas. Both isolates were highly aggressive in greenhouse tests, causing a mean of 90% wilt of all 17 watermelon cultivars tested, 10 of which are considered highly wilt-resistant. Comparisons with isolates of races 0, 1, and 2 (sensu Cirulli) indicated that the Texas isolates were identical to race 2, first described in Israel in 1973.