Fungicidal Control of Sclerotinia sclerotiorum in Soil with a Combination of Benomyl and Thiram. O. Yarden, Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100. Y. Ben-Yephet, Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250; J. Katan, Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100; and N. Aharonson, Department of Chemistry of Pesticides and Natural Products, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel. Plant Dis. 70:738-742. Accepted for publication 12 November 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-738.

In previous experiments, the fungicide thiram suppressed benomyl degradation and prolonged its activity in the soil. Combined application of benomyl and thiram improved control of Sclerotinia sclerotiorum in soil. The effect of the combined fungicidal treatments was expressed by a reduction of sclerotial germination, apothecial production by germinating sclerotia, rate of apothecial production, and delay in apothecial emergence. A reduction in apothecial emergence as a result of the combined treatment was also observed in the field. Improved control of Verticillium wilt was also observed under field conditions. The low mobility of benomyl in the soil profile combined with the extended persistence of fungitoxic residues resulting from the thiram amendment contribute to the improved control of the pathogen by benomyl in soil while providing an option for benomyl dosage reduction. Thiram may prove useful as an extender and fortifier of benomyl activity in soil.

Keyword(s): benzimidazole fungicides, carbendazim, chinese cabbage, iprodione, lettuce, vinclozolin.