Pathogenicity Groups of Bean Common Mosaic Virus in the USDA Phaseolus Germ Plasm Collection. R. E. Klein, Assistant Plant Pathologist, Department of Plant Pathology, Washington State University, Pullman 99164-6430. S. D. Wyatt, W. J. Kaiser, and R. O. Hampton. Associate Professor, Department of Plant Pathology, Washington State University, Pullman 99164-6430; Research Plant Pathologist, USDA-ARS, Western Regional Plant Introduction Station, Washington State University, Pullman 99164-6402; and Research Plant Pathologist, USDA-ARS, Oregon State University, Corvallis 97331. Plant Dis. 76:1263-1265. Accepted for publication 24 August 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1263.

The pathogenicity groups of seedborne bean common mosaic virus (BCMV) strains in the USDA Phaseolus germ plasm collection were identified by systemic infection of differential P. vulgaris cultivars. All BCMV pathogroups (PG)(sensu Drijfhout) except PG III were detected, and 10 BCMV cultures simulated a new pathogroup, PG VIII. Six of these cultures, however, were resolved into two different BCMV strains, and 14 of 19 PG VI-simulating cultures were similarly resolved. PG V cultures were rare, except in mixed infections with other pathogroups. None of the BCMV cultures simulating PG VI induced temperature-insensitive necrosis on cultivars containing the I gene.