Exserohilum turcicum Virulent on Corn with the Ht Resistance Gene in Ohio. P. E. Lipps, Assistant Professor, Ohio Agricultural Research and Development Center, Wooster 44691. R. E. Hite, Plant Pathologist, Animal and Plant Health Inspection Service, USDA, Department of Plant Pathology, The Ohio State University, Columbus 43210. Plant Dis. 66:397-398. Accepted for publication 23 July 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-397.

Isolates of Exserohilum turcicum from commercial and seed production cornfields in Hardin, Mercer, and Preble counties, Ohio, caused necrotic lesions on inbreds and hybrids of Zea mays with the Ht gene. When these isolates were inoculated onto inbred NN14B containing the Ht2 gene, resistant-type, chlorotic lesions developed indicating the isolates were race 2. None of the isolates were virulent on NN14B carrying the Ht2 gene and none were avirulent on lines carrying the Ht gene; therefore race 3 has not as yet been found in Ohio.

Keyword(s): Helminthosporium turcicum, maize, monogenic resistance, northern corn leaf blight.