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Fusarium Wilt of Chrysanthemum: Cultivar Susceptibility and Chemical Control. D. L. Strider, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Plant Dis. 69:564-568. Accepted for publication 3 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-564.

Recent serious outbreaks of Fusarium wilt of pot-grown chrysanthemums in North Carolina were caused by Fusarium oxysporum f. sp. chrysanthemi, which was isolated frequently from cuttings of susceptible and resistant cultivars received from a commercial propagator. The cultivars Cirbronze, Royal Trophy, and Yellow Delaware were most susceptible to the pathogen, whereas Jamboree, Puritan, and Tuneup were most resistant. Of 10 cultivars screened for resistance to F. oxysporum f. sp. tracheiphilum, none were highly susceptible, but Escapade and Promenade were moderately susceptible and Cirbronze, Jamboree, Pinktive, Puritan, Royal Trophy, Tuneup, and Yellow Delaware were highly resistant. A single drench of thiophanate-methyl at the rate of 0.21 g a.i./L applied 2, 6, or 10 days after inoculation of rooted cuttings gave excellent control without phytotoxicity. Benomyl also provided control, but 1.2 g a.i./L was required. Thiophanate-methyl (25%) + ethazol (75%) was effective and nonphytotoxic at 0.90 g a.i./L (0.22 g a.i. of thiophanate-methyl per liter). The combination treatment, benomyl + lime + nitrate, gave good control but caused slight stunting and chlorosis.