Pea Streak and Alfalfa Mosaic Viruses in Alfalfa: Reservoir of Viruses Infectious to Pisum Peas. R. O. Hampton, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Oregon State University, Corvallis 97331. K. A. Weber, Research Assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Plant Dis. 67:308-310. Accepted for publication 21 August 1982. 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, 1983. DOI: 10.1094/PD-67-308.

Alfalfa (Medicago sativa) plant samples from four diverse northwestern U.S. production areas were tested by enzyme-linked immunosorbent assay for pea streak virus (PSV) and alfalfa mosaic virus (AMV). Plants from all fields 5 yr or older in all areas contained PSV and AMV; neither virus was detected in two plantings that were less than 2 yr old. At least 40% of the sampled plants were PSV-infected in five of seven geographic locations; the other two locations contained 13 and 24% infected plants. Incidence of PSV-infected plants was independent of proximal plantings of peas or other known PSV hosts. Coincidence of PSV and AMV in sampled alfalfa plants exceeded 60% in five of seven locations. No seedborne PSV was demonstrated in 670 alfalfa seedlings grown from seed obtained from PSV-infected fields, whereas at least 2% frequency of seedborne AMV was detected in the same seedlings.

Keyword(s): enzyme-linked immunosorbent assay, Idaho, Montana, Oregon, Pisum sativum, red clover vein mosaic virus, Washington.