Wheat Scab in Soft Red Winter Wheat in Indiana in 1986 and Its Relation to Some Quality Measurements. John Tuite, Professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907. Gregory Shaner, and Robert J. Everson. Professors, Department of Botany and Plant Pathology, and Analytical Chemist, Animal Disease Diagnostic Laboratory, Purdue University, West Lafayette, IN 47907. Plant Dis. 74:959-962. Accepted for publication 10 April 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0959.

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 lb/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 ≥ 2 ppm. For the 1986 crop, a level of scab ≥ 2%, a test weight ? 809 kg m^-3 (54 lb/bu), or seed germination ≤ 80% could be used as criteria for a decision to analyze a grain sample chemically for DON.