Development of Barley Resistant to Spot Blotch and Genetics of Resistance. Roy D. Wilcoxson, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Donald C. Rasmusson, and Monte R. Miles. Professor, Department of Agronomy and Plant Genetics, and Former Research Assistant, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 74:207-210. Accepted for publication 6 September 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0207.

Cree, Manker, Morex, and Robust are barley (Hordeum vulgare) cultivars resistant to spot blotch (caused by Bipolaris sorokiniana) that have been released by the University of Minnesota. The latter two cultivars are planted in about 95% of the barley-producing area in Minnesota and are widely grown in other areas. The resistance of these four cultivars and of many advanced breeding lines was derived from CI 7117-77 through ND B-112 and Dickson, which were developed at North Dakota State University. This resistance has been stable since its discovery in the mid-1950s. Other germ plasm resistant to B. sorokiniana has been developed from Wisc 691-1, CI 1227, CI 6311, CI 9584, and H. agriocrithon, sources that differ from ND B-112. In an inheritance study, resistance from ND B-112 and that from the other sources appeared to be conditioned by one or two genes. Some progenies of Minn 33 (derived from ND B-112) crossed with resistant lines that trace to CI 1227 and CI 6311 were moderately susceptible, indicating that different resistance genes were involved.