Abstract
A severe outbreak of wheat scab in the northern portion of Indiana during the 1986 growing season was associated with prolonged wet weather during and after anthesis. The combined effects of scab and other head and foliar diseases greatly reduced yield and test weight. Samples of grain from throughout Indiana were analyzed to determine the incidence of scab, germination, test weight, and concentration of deoxynivalenol (DON), a toxin produced by Gibberella zeae. Grain samples from 43 of 44 counties had scab. Scabby kernels averaged 2.9% by weight and test weight averaged 821 g/L (54.8 Ib/bu). Kernel infection by G. zeae averaged 23%. DON was detected in 88% of the samples, and the mean concentration was 0.6 parts per million (ppm). Nine percent of the samples had DON .gtoreq. 2 ppm. For the 1986 crop, a level of scab .gtoreq. 2%, a test weight .ltoreq. 809 kg m-3 (54 lb/bu), or seed germination .ltoreq. 80% could be used as cirteria for a decision to analyze a grain sample chemically for DON. [Other fungi include Fusarium spp. Aspergillus spp. Penicillium spp. and Epicoccum spp.].

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