VIEW ARTICLE

Ecology and Epidemiology

Population Dynamics of Trichoderma viride in Steamed Plant Growth Medium. J. J. Marois, Research plant pathologist, Soilborne Diseases Laboratory, Plant Protection Institute, and Florist and Nursery Crops Laboratory, Horticultural Science Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, Present address of senior author: Department of Plant Pathology, University of California, Davis 95616; J. C. Locke, research plant pathologist, Soilborne Diseases Laboratory, Plant Protection Institute, and Florist and Nursery Crops Laboratory, Horticultural Science Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 75:115-118. Accepted for publication 12 July 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-115.

Some factors affecting the saprophytic proliferation of T-1-R9, a benomyl-tolerant isolate of Trichoderma viride that controls Fusarium wilt of chrysanthemum, were investigated in a freshly steamed plant growth medium. A reduction in the proliferation of T-1-R9 was observed when the medium was diluted by 75% with silicate sand. The addition of T-1-R9 increased the total population density of T. viride in the medium, which suggests that instraspecific competition was not an important limiting factor in colonization of the medium by T. viride. The addition of T-1-R9 to freshly steamed growth medium resulted in increased CO₂ evolution during the first 12 days which indicated an increased level of nutrient utilization. This was further correlated with a reduction in the final population density of Fusarium oxysporum f. sp. chrysanthemi and in disease incidence.