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Postharvest Pathology and Mycotoxins

Cultural Characteristics, Pathogenicity, and Zearalenone Production by Strains of Gibberella zeae Isolated from Corn. D. Cullen, Graduate student, Department of Plant Pathology, University of Wisconsin, Madison 53706; R. W. Caldwell(2), and E. B. Smalley(3). (2)(3)Research associate, and professor, respectively, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 72:1415-1418. Accepted for publication 13 April 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1415.

Isolates of Gibberella zeae from naturally infected corn kernels were classified into two groups based on colony morphology on potato-dextrose agar (PDA). The most frequently isolated strain (type A) grew rapidly and produced red-pigmented colonies with abundant aerial mycelium. In culture, this type produced varying amounts of zearalenone (1 to 433 mg/L) and was consistently pathogenic in field trials. In contrast, the type B strain was isolated less frequently (5% of isolations), grew slowly on PDA, and developed appressed brownish yellow colonies. Type B strains were nonpathogenic, but produced high levels of zearalenone in culture (up to 2,033 mg/L). Among pathogenic strains (type A), concentrations of zearalenone produced in infected ears were positively correlated with production in culture.

Additional keywords: F-2 toxin, Fusarium graminearum.