Falcate-spored species of Colletolrichum on soybean1

Field collections of falcate-spored isolates of Colletotrichum were obtained from various soybean plant parts. Two colony types were distinguished; one was identified as C. dematium f. truncatum, the other as C. capsici. C. capsici was pathogenic on bell pepper, tomato, and eggplant seedlings and on cotton seedlings and bolls. The fungus was nonpathogenic or weakly pathogenic on soybean seedlings, with pathogenicity limited primarily to cotyledons. In contrast, C. d. f. truncatum was extremely virulent on soybean seedlings and caused considerable pre- and postemergence seedling death. C. capsici was isolated more frequently from pods and leaves than from stems and seeds. Compared to C. d. f. truncatum, C. capsici was rare in seeds, but maximum frequencies of the two fungi on leaves, stems, and pods were comparable. The occurrence of C. capsici on soybean in the United States is a new record, and it extends the host range of the fungus in the United States.