Use of Host Resistance, Trichoderma, and Fungicides to Control Soilborne Diseases and Increase Seed Yields of Peas. John M. Kraft, Research Plant Pathologist, Vegetable Crops Production, USDA, ARS, Prosser, WA 99350. George C. Papavizas, Research Plant Pathologist, Soilborne Diseases Laboratory, Plant Protection Institute, USDA, ARS, Beltsville, MD 20705. Plant Dis. 67:1234-1237. Accepted for publication 28 April 1983. 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, 1983. DOI: 10.1094/PD-67-1234.

Damping-off and root rot of peas, caused by Pythium ultimum and Fusarium solani f. sp. pisi, was studied in 1980 and 1981 at Prosser, WA. In both years, seeds of a cultivar highly susceptible to both pathogens (Dark Skin Perfection) and breeding lines resistant to both pathogens (792016, 792028, 80-1284) were treated with fungicides, spores of Trichoderma, or both. In soil with natural infestation of F. solani and P. ultimum, the resistant breeding lines outyielded the susceptible cultivar regardless of seed treatment in both years. In 1980, seed yields of resistant lines were unaffected by seed treatments; however, the highest seed yields with the susceptible Dark Skin Perfection were obtained with the seed treatment combining metalaxyl and T. harzianum spores. In 1981, seeds treated with T. viride gave the highest plant stands and seed yields, with both susceptible and resistant pea lines, although results with captan or metalaxyl were not statistically different from seed yields obtained with T. viride. T. viride (T-1-R4) was detected in the rhizosphere of peas in bloom, resulting from planting seed coated with conidia. Seed rot and preemergence and postemergence damping-off were reduced by the various treatments, as evidenced by differences in plant stands. Root rot, caused primarily by F. solani f. sp. pisi, was not controlled.