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Evidence for Toxin Production by a Strain of Cephalosporium gregatum. Lynn E. Gray, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, North Central Region, U.S. Regional Soybean Laboratory, Urbana, Illinois 61801; Donald W. Chamberlain, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, North Central Region, U.S. Regional Soybean Laboratory, Urbana, Illinois 61801. Phytopathology 65:89-90. DOI: 10.1094/Phyto-65-89.

Extracts made from soybean stems infected with the Type I (defoliating) isolate of Cephalosporium gregatum induced wilting and death of detached trifoliolate soybean leaves, but extracts made from stems infected with the Type II (non-defoliating) (ATCC) culture did not. Both extracts caused vascular browning in the petiole. Leaves of cultivars Amsoy 71, Beeson, Calland, and Wayne wilted after three days in the Type I extract; P.I.’s 84,946-2 and 86,150 did not. Wilting was not entirely attributable to vascular plugging. It is suggested that a toxin produced by Type I isolates of C. gregatum is responsible for the difference in symptomatology induced by the two isolates.