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Ecology and Epidemiololgy

Factors Affecting Parasitic Activity of Sporidesmium sclerotivorum on Sclerotia of Sclerotinia minor in Soil. P. B. Adams, Soilborne Diseases Laboratory, Plant Protection Institute, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705; W. A. Ayers, Soilborne Diseases Laboratory, Plant Protection Institute, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 70:366-368. Accepted for publication 17 October 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-366.

Laboratory experiments indicated that the newly described mycoparasite Sporidesmium sclerotivorum may be a useful agent for the control of plant diseases caused by Sclerotinia minor. In field soils to which sclerotia of S. minor and inoculum of S. sclerotivorum were added, infection of the sclerotia by the mycoparasite began within 2 wk, and the sclerotia were completely destroyed within about 10 wk under appropriate environmental conditions. The optimum conditions for infection and decay of sclerotia in soil were 20–25 C, pH 5.5–7.5, and soil water potentials of –8 bars and higher. Infection and decay of sclerotia occurred after a sand-sclerotia culture of S. sclerotivorum was added to soils at rates as low as 2 × 10³ spores per 100 g of soil.