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Colletotrichum truncatum Borne Within the Seedcoat of Soybean. R. W. Schneider, Graduate Research Assistant, Department of Plant Pathology, University of Illinois, Urbana 61801; O. D. Dhingra(2), J. F. Nicholson(3), and J. B. Sinclair(4). (2)(3)(4)Graduate Research Assistant, former Graduate Research Assistant and Professor, respectively, Department of Plant Pathology, University of Illinois, Urbana 61801, (3)Present address: Biochemicals Department, E. I. duPont de Nemours and Co., Inc., Wilmington, DE 19898. Phytopathology 64:154-155. DOI: 10.1094/Phyto-64-154.

Colletotrichum truncatum was isolated from, and observed within, the seedcoats of surface-sterilized soybean seeds, but not from embryos or cotyledons of the same seeds. The mycelium was confined to the middle “hourglass” layer of the seedcoat and to naturally occurring wounds. C. truncatum also was obtained from water washings of infected soybean seeds. The seedcoat symptoms of soybean seed infected with C. truncatum are similar to those described for Macrophomina phaseolina (Rhizoctonia bataticola). Histochemical tests showed the hourglass layer to consist of, in part, an amorphous starch-rich matrix.