Top Dieback of Soybean Caused by Diaporthe phaseolorum var. caulivora. Thomas W. Hobbs, Graduate Research Associate, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster 44691. A. F. Schmitthenner, Professor, and C. Wayne Ellett, Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster 44691 and The Ohio State University, Columbus 43210; and R. E. Hite, Adjunct Associate Professor and Plant Disease Specialist, USDA-APHIS-PPQ, Department of Plant Pathology, The Ohio State University, Columbus 43210. Plant Dis. 65:618-620. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-618.

Top dieback of soybean caused by Diaporthe phaseolorum var. caulivora (Dpc) developed late in the season and was distinct from soybean stem canker, which is also incited by Dpc. Symptoms of top dieback were premature death of the upper five or six internodes. In field studies, isolates of Dpc induced dieback in tip-inoculated plants and stem canker in plants inoculated in lower internodes. Dpc was isolated three times more frequently from seeds than from pods from which seeds were taken.

Keyword(s): D. phaseolorum var. sojae, Phomopsis sp., pod and stem blight.