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Etiology

Fungal Flora of Crambe Seeds and Virulence of Alternaria brassicicola. R. A. Kilpatrick, Research Plant Pathologist, Germplasm Resources Laboratory, Plant Genetics and Germplasm Institute, Agricultural Research Service, U.S. Department of Agriculture, BARC-West Beltsville, MD 20705; Phytopathology 66:945-948. Accepted for publication 11 February 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-945.

Fifty-one samples of crambe seed from Illinois, Indiana, Maryland, and Ohio were plated on PDA and the associated fungi were identified. Alternaria spp. comprised 86% of the isolates. Alternaria tenuis was most commonly isolated (47%) followed by A. brassicicola (39%). No difference was noted in the kind of fungi isolated among sources, states, or years, but a greater array of fungi was isolated from poor-quality seed. Crambe plant selections and miscellaneous crucifers varied in susceptibility to A. brassicicola. Symptom expression and disease severity were influenced by inoculum density, postinoculation drying of leaves, duration of incubation period, and the leaf surface inoculated. Virulence of the organism was retained over one year when isolates were cultured on filter paper and stored in petri dishes at 5 C.