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Heat-Induced Susceptibility to Nonpathogens and Cross-Protection Against Phytophthora megasperma var. sojae in Soybean. D. W. Chamberlain, Research Plant Pathologist, Plant Science Research Division, ARS, USDA, Urbana, Illinois 61801; Phytopathology 62:645-646. Accepted for publication 4 January 1972. DOI: 10.1094/Phyto-62-645.

Of 17 species of fungi, all nonpathogens of soybean, four (Ceratocystis fimbriata, Fusarium moniliforme, Gibberella zeae, and Helminthosporium turcicum) killed heat-treated Harosoy soybean plants. These four also cross-protected Harosoy plants against Phytophthora megasperma var. sojae. Ten of the nonpathogens caused no infection on heat-treated plants; six of the 10 gave good cross-protection against P. megasperma var. sojae. Apparently, resistance to nonpathogens in soybeans is not governed by a single mechanism.