Effects of Bean Pod Mottle Virus on Soybean Seed Maturation and Seedborne Phomopsis spp.. T. S. ABNEY, Plant Pathologist, Crop Production and Pathology Unit, Agricultural Research Service, U.S. Department of Agriculture. L. D. PLOPER, Former Graduate Research Assistant, Botany and Plant Pathology Department, Purdue University, West Lafayette, IN 47907. Plant Dis. 78:33-37. Accepted for publication 24 August 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0033.

Maturation rate, measured as length of late-season growth stage intervals, was studied in diverse soybean genotypes to determine if bean pod mottle virus (BPMV) infection altered the role of plant and seed drydown when seed infection by Phomopsis spp. increased. Foliage symptoms, stunting, and significant yield reductions due to BPMV occurred in all but one of the 12 soybean entries. Pod infection was consistently increased by BPMV, whereas seed infection was significantly increased in genotypes only if the virus infection delayed the rate of seed maturation. BPMV delayed maturity by extending the length of late-season growth stage intervals and increased seed infection in the soybean entries susceptible or moderately resistant to seed diseases. Effects of BPMV on soybean genotypes that matured under the same environmental conditions indicate that initial levels of seed infection are directly related to the rate of pod and seed maturation. Modifications by BPMV in the R7-R8 interval that delayed harvest maturity of soybean entries susceptible and moderately resistant to seed infection were correlated with increases in levels of seedborne Phomopsis spp.