In 1996, cantaloupe (Cucumis melo L. cv. Durango) vines in two fields exhibited wilt, vascular discoloration, and necrotic streaks on the stems. Fusarium oxysporum Schlechtend.:Fr. was isolated from the stems of vines from both fields. One isolate from each field was compared with known isolates of F. oxysporum f. sp. melonis (Leach & Currence) W.C. Snyder & H.N. Hansen races 1 and 2 in a differential host range experiment in the greenhouse. Three-week-old seedlings were root-dip inoculated with monoconidial isolates at a concentration of 5 × 105 spores per ml. Control plants were dipped in water. In two experiments, the test isolates killed the susceptible varieties Top Mark and Magnum .45 and the race 2 resistant varieties Durango, Gold Mine, and Perlita FR. Seedlings of variety Charentais with the Fom2 gene conferring resistance to race 1 were resistant to both test isolates. It was determined that both of these isolates are associated with vegetative compatibility group (VCG) 0134 (1). This is the first report of race 1 and VCG 0134 of F. oxysporum f. sp. melonis causing Fusarium wilt of muskmelon in the Central Valley of California, and the first reported occurrence of race 1 in California since 1973 (2). Cantaloupe varieties currently grown in California are susceptible to race 1 of F. oxysporum f. sp. melonis
References: (1) D. J. Jacobson and T. R. Gordon. Phytopathology 78:668, 1988. (2) J. V. Leary and W. D. Wilbur. Phytopathology 66:15, 1976.
