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Postharvest Pathology and Mycotoxins

Incidence, Geographic Distribution, and Toxigenicity of Fusarium Species in South African Corn. W. F. O. Marasas, National Research Institute for Nutritional Diseases, South African Medical Research Council, P.O. Box 70, Tygerberg 7505, South Africa; N. P. J. Kriek(2), V. M. Wiggins(3), P. S. Steyn(4), D. K. Towers(5), and T. J. Hastie(6). (2)(3)National Research Institute for Nutritional Diseases, South African Medical Research Council, P.O. Box 70, Tygerberg 7505, South Africa; (4)(5)National Chemical Research Laboratory, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa; (6)Institute for Biostatistics, South African Medical Research Council, P.O. Box 70, Tygerberg 7505, South Africa. Phytopathology 69:1181-1185. Accepted for publication 7 May 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-1181.

Three Fusarium spp. were isolated from South African corn produced in three different geographic areas. Fusarium moniliforme var. subglutinans was the most prevalent, followed by F. moniliforme and F. graminearum. The mean percentage of kernel infection caused by all three species increased during storage. The occurrence of each species was maximal in a specific geographic area: F. moniliforme predominated in a subtropical area (the warmest climate of the three areas), F. moniliforme var. subglutinans in the most temperate area, and F. graminearum in the area with an intermediate climate. The highest percentage of toxic F. moniliforme var. subglutinans isolates (identified by the toxicity of infected corn kernels to ducklings) was obtained from the area in which it occurred most frequently. A higher proportion of toxic F. moniliforme var. subglutinans isolates from this area produced moniliformin in culture than did those from the other two areas. Moniliformin was produced in culture at levels ranging from 120 to 1,170 mg/kg by 16 of 23 toxic F. moniliforme var. subglutinans isolates, but by 0 of 14 toxic F. moniliforme isolates. Whether moniliformin occurs naturally in corn has not yet been established.