Aflatoxin occurrence in 1973 corn at harvest. II. Mycological studies
1976
Hesseltine, C.W. | Shotwell, O.L. | Kwolek, W.F. | Lillehoj, E.B. | Jackson, W.K. | Bothast, R.J.
Since aflatoxin is formed in maize in the field before harvest, the objectives of this study were to determine at harvest (a) the amount of Aspergillus flavus-infected maize kernels, (b) the amount of A. flavus spores on the surface of maize, (c) the total amount of fungus-infected kernels, (d) the occurrence of A. flavus spores in and on insects from maize reported in the 1st paper of this series (Cereal Chem. 52 : 603-611, 1975), and (e) the correlation between A. flavus infection and occurrence of aflatoxin. The maize was collected at harvest from 7 counties in northeastern S. Carol. and dried to <13% moisture as quickly as possible. Of the 152 aflatoxin-positive samples, 120 showed 1 or more kernels internally infected with A. flavus and of the 145 aflatoxin negative samples, 59 showed infection. Of the 297 samples examined, 276 had 1 or more kernels with surface contamination of A. flavus spores, and in 75 of the samples every kernel was contaminated. When kernels were surface disinfected, 224 samples (50 kernels each) showed 100% internal mould contamination. One or more kernels of 185 samples were infected with A. flavus; this number represents 60% of the total samples. Of the 375 insects collected and examined for A. flavus from the maize samples, 247 showed A. flavus present. Of the 85 rice weevils, 78 were carrying A. flavus spores and of the other 290 insects, 165 were contaminated. Besides A. flavus, the predominant infecting fungi internally were 2 spp. of Penicillium and Fusarium. Members of the Mucorales were rarely seen.
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