Mating Types, Virulence, and Cultural Characteristics of Exserohilum turcicum Race 2. W. L. Pedersen, Assistant Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. L. J. Brandenburg, Undergraduate Student, Department of Plant Pathology, University of Illinois, Urbana 61801. Plant Dis. 70:290-292. Accepted for publication 25 September 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-290.

Sixty-five isolates of Exserohilum turcicum race 2 were obtained from 13 locations in the U.S. corn belt. Twenty-seven isolates mated with the A mating type, but 38 isolates failed to mate with either A or a mating types. In the greenhouse, isolates from Florida, Pennsylvania, and West Virginia produced significantly (P = 0.05) longer lesions on the corn hybrid A632×A619 than isolates from Iowa, Illinois, and Indiana. There were no differences among isolates for incubation period. Isolates from Delaware, Florida, Pennsylvania, and West Virginia had significantly larger radial growth on lactose-casein hydrolysate agar after 10 days at 20 C than isolates from Iowa, Illinois, and Indiana. Conversely, isolates from Champaign and Iroquois counties in Illinois and La Grange County in Indiana had significantly larger radial growth diameters at 28 than at 20 C.

Keyword(s): host-parasite interaction, northern leaf blight, parasitic fitness, Setosphaeria turcica.