1. Crop Genetics and Production Research Unit, USDA-ARS, Stoneville, Mississippi 38766; Corn Host Plant Resistance Research Unit, USDA-ARS, Mississippi State, Mississippi 39762; Delta Research and Extension Center, Mississippi State University, Stoneville, Mississippi 38766; Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota 55108; and College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455