1. Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin 53706-1598;
2. Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97330;
3. Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843-2132;
4. Department of Plant Pathology, Michigan State University, East Lansing, Michigan 48824-1312;