Resistance to Rhizoctonia Stem Rot in Peas as Influenced by Temperature, Watering Method, and Period of Disease Development. M. A. Shehata, Associate Scientist, Department of Horticultural Science and Landscape Architecture, University of Minnesota, St. Paul 55108. D. W. Davis, Professor, Department of Horticultural Science and Landscape Architecture, and N. A. Anderson, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 68:22-24. Accepted for publication 11 July 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-22.

Under controlled environmental conditions, disease severity of susceptible and moderately resistant pea cultivars to Rhizoctonia solani AG4 varied with temperature, period of disease development, and method of watering. The distinction between susceptible and moderately resistant plants was difficult to determine when plants were kept either under high temperature and high soil moisture for a long period or under low temperature and high soil moisture for a short period. A breakdown of the moderate resistance to this disease occurred under environmental conditions that favored the pathogen more than the host. Seedlings of a susceptible and of a moderately resistant cultivar of different ages (1, 2, and 3 wk) gave the same disease reaction. The maturing pea stem apparently did not develop disease resistance.