Relationships Among Cercospora kikuchii, Other Seed Mycoflora, and Germination of Soybeans in Puerto Rico and Illinois. P. R. Hepperly, Assistant Professor, Department of Crop Protection, University of Puerto Rico, Mayaguez 00708. J. B. Sinclair, Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. Plant Dis. 65:130-132. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-130.

Seeds from similar field plots planted to four soybean (Glycine max) cultivars in Puerto Rico and Illinois were assayed for seedborne mycoflora. The predominant fungus recovered was Cercospora kikuchii from Puerto Rico seeds and Phomopsis sp. from Illinois seeds. Purple-stained seed had higher germination at normal harvest than unstained seed. C. kikuchii from Puerto Rico-grown seeds was antagonistic to seedborne Fusarium spp. and Phomopsis sp., which were recovered six and three times more often, respectively, from unstained than from purple-stained seeds. C. kikuchii and Phomopsis sp. were not antagonistic in Illinois seeds except when incidence of C. kikuchii exceeded 10%. Recoveries of Fusarium and Phomopsis increased and germination and recoveries of C. kikuchii decreased when harvest was delayed in Puerto Rico. Multiple regression equations related the occurrence of C. kikuchii, Fusarium, and Phomopsis to reduced soybean seed germination in Puerto Rico. In Illinois, variation in the incidence of Phomopsis explained most of the variation in germination.

Keyword(s): Diaporthe phaseolorum var. sojae.