Populations of Fungi in Soil After Chemigation with Chlorothalonil and Tebuconazole via Center-Pivot Irrigation. Donald R. Sumner, Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748. T. B. Brenneman, and Gerald W. Harrison. Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748, and ISK Biotech Corp., Albany, GA 31707. Plant Dis. 75:999-1004. Accepted for publication 2 April 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0999.

Chlorothalonil and tebuconazole were applied to peanut (Arachis hypogaea) through a center-pivot irrigation system (chemigation), a pivot-mounted underslung boom, or ground sprays. Populations of Rhizoctonia solani AG-4, R. zeae, and Sclerotium rolfsii in soil at midseason and at digging were variable and were not influenced significantly by chemical treatment or application method. Chemigation with tebuconazole, but not with chlorothalonil, reduced populations of total fungi in soil at digging, and in one test all applications of tebuconazole reduced populations of binucleate Rhizoctonia CAG-3. Populations of other binucleate Rhizoctonia spp. were not affected by treatments with either chemical. Rhizoctonia limb rot was correlated significantly with populations of R. solani AG-4 in soil in only one of four experiments.