Influence of Genotype and Environment on Kernel Discoloration of Midwestern Malting Barley. M. R. Miles, Graduate Research Assistant, Department of Plant Pathology, University of Minnesota, St. Paul 55108. R. D. Wilcoxson, D. C. Rasmusson, J. Wiersma, and D. Warnes. Professor, Department of Plant Pathology, and Professor, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108; Associate Professor and Agronomist, University of Minnesota Northwest Experiment Station, Crookston 56716; and Professor, University of Minnesota, West Central Experiment Station, Morris 56267. Plant Dis. 71:500-504. Accepted for publication 22 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0500.

Thirty barley cultivars and lines grown at Crookston, Morris, Rosemount, and St. Paul, MN, during 1982 and 1983 were evaluated for black stain and carameling. Chevron was resistant to both black stain and carameling, and Karl was susceptible to both. The potential and commercial cultivars had intermediate resistance to black stain, but they were more severely black-stained than lines with a kernel discoloration resistant parent. The barleys of western origin were intermediate between the commercial cultivars and the susceptible checks. Most of the barleys were susceptible to carameling. CI 9539 and the lines with a resistant parent were as severely carameled as the potential and commercial cultivars. Effective selection for resistance to black stain could be carried out at a single location when irrigation and inoculation with Bipolaris sorokiniana were used. Irrigation significantly increased black stain severity, whereas inoculation increased black stain severity but not significantly (P = 0.05). In the nonirrigated environments, black stain was most severe when rainfall was highest. Carameling severity was not influenced by irrigation or inoculation, but under natural conditions, carameling was most severe when rainfall was highest. Differences in black stain and carameling could be detected among genotypes screened under natural conditions at two locations for 2 yr.