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Trichoderma hamatum Effects on Seed and Seedling Disease Induced in Radish and Pea by Pythium spp. or Rhizoctonia solani. G. E. Harman, Associate professor, Department of Seed and Vegetable Sciences, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; I. Chet(2), and R. Baker(3). (2)Professor, Department of Plant Pathology and Microbiology, the Hebrew University of Jerusalem, Rehovot, Israel; (3)Professor, Department of Botany and Plant Pathology, Colorado State University, Fort Collins 80523. Phytopathology 70:1167-1172. Accepted for publication 26 May 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-1167.

In laboratory studies, treatment of pea or radish seeds with conidia of Trichoderma hamatum in a Methocel slurry protected seeds and seedlings from Pythium spp. or Rhizoctonia solani, respectively, nearly as effectively as fungicide seed treatments. By comparison, treatment of radish or pea seeds with Chaetomium globosum was less effective than T. hamatum. A combination of C. globosum and T. hamatum was less effective on peas than was T. hamatum alone. In soils planted with seeds treated with T. hamatum, numbers of Trichoderma propagules increased approximately 100-fold; replanting this soil once or twice with untreated seeds resulted in lower disease incidence than planting in soils originally planted with C. globosum-treated or untreated seeds. In soils containing T. hamatum, lower densities of R. solani and Pythium were present than in soils without T. hamatum. Trichoderma hamatum and C. globosum grew abundantly on treated seeds, while T. harzianum grew little.

Additional keywords: biological control, soil fungi, fungicides, Pisum sativum, Raphanus sativus, mycoparasitism.