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Physiology and Biochemistry

Apparent Systemic Effect of Colletotrichum truncatum and C. lagenarium on the Interaction Between Soybean and C. truncatum. J. A. Wrather, Associate professor, Department of Plant Pathology, University of Missouri Delta Center, Portageville 63873; J. M. Elrod, senior research technician, Department of Plant Pathology, University of Missouri Delta Center, Portageville 63873. Phytopathology 80:472-474. Accepted for publication 23 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-472.

Laboratory studies were conducted to determine whether the interaction between soybean cotyledons and Colletotrichum truncatum (causal agent of soybean anthracnose), C. lagenarium (a cucumber pathogen), and heat-killed C. lagenarium spore suspensions interfered with the interaction between the soybean epicotyl and C. truncatum. Cotyledon treatments, injection with spore suspensions of C. truncatum, C. lagenarium, and heat-killed C. lagenarium, affected the size of lesions that developed on epicotyls inoculated with C. truncatum. Epicotyl lesions were significantly smaller than the control when the cotyledons were injected 24?96 hr before epicotyl inoculation with C. truncatum. Epicotyl lesions were not significantly different in size when the cotyledon treatments and epicotyl inoculation occurred simultaneously. Lesions rarely developed on epicotyls inoculated with C. truncatum when cotyledons had been previously treated with heat-killed C. lagenarium. The cotyledon treatments protected the epicotyl against C. truncatum.