Bulletin #$2273, Rhizoctonia Disease on Potatoes (PDF) Steven B. Johnson, crops specialist University of Maine Cooperative Extension. Simeon S. Leach, Ph.D., Research Plant Pathologist, USDA Agriculture Research Service For information about UMaine Extension programs and resources, visit extension.umaine.edu. Find more of our publications and books at extension.umaine.edu/publications/. History Rhizoctonia solani sclerotia