VIEW ARTICLE

Disease Control and Pest Management

Effect of Mycelial Preparations of Trichoderma and Gliocladium on Populations of Rhizoctonia solani and the Incidence of Damping-Off. J. A. Lewis, Soil scientist, Soilborne Diseases Laboratory, Plant Protection Institute, U.S. Department of Agriculture, Beltsville, MD 20705; G. C. Papavizas, plant pathologist, Soilborne Diseases Laboratory, Plant Protection Institute, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 75:812-817. Accepted for publication 26 February 1985. 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, 1985. DOI: 10.1094/Phyto-75-812.

Mycelial preparations of eight of 14 isolates of Trichoderma spp. and Gliocladium virens reduced survival of Rhizoctonia solani at least 50% in pathogen-infested beet seed in soil and in soil infested with sand/cornmeal inoculum of the pathogen. All isolates reduced saprophytic growth of R. solani from infested beet seed into soil. Isolates of T. hamatum and G. virens were more effective than those of T. harzianum and T. viride. Population densities of all isolates increased 10⁴- 10⁶-fold during 3 wk of incubation after mycelial preparations were added to soil. Conidial preparations of isolates, added to soil in amounts equal to propagules in mycelial preparations, did not reduce survival of R. solani or its growth through the soil. Mycelial preparations, but not conidia, of most isolates of Trichoderma spp. and G. virens prevented damping-off of cotton, sugar beet, and radish seedlings in the greenhouse. There was no correlation between population density of antagonists and pathogen survival or damping-off. There was a highly significant negative correlation between stand in all three crops and pathogen survival in soil.