Barley Yellow Dwarf in California: Vector Competence and Luteovirus Identification. F. E. Gildow, Assistant Professor, Department of Plant Pathology, University of California, Berkeley 94720. W. F. Rochow, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, and Professor, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Plant Dis. 67:140-143. Accepted for publication 10 June 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-67-140.

Samples of small grains collected in 1981 from eight counties in California were tested by aphid transmission and by enzyme-immunosorbent assays for luteoviruses that cause barley yellow dwarf. California isolates were compared with three previously characterized in New York: RPV, MAV, and PAV. Of 128 plants sampled, 75% were infected by luteoviruses similar to PAV, 19% by viruses similar to MAV, and 6% by RPV-like luteoviruses. When clones of aphids collected in California were compared with those from New York for transmission of five virus isolates, no difference in vector competence occurred among clones of Rhopalosiphum padi. Two California clones of Metopolophium dirhodum efficiently transmitted MAV and PAV but not a California luteovirus similar to PAV (CA-PAV). Both California and New York clones of Sitobion avenae transmitted MAV and PAV, but California S. avenae transmitted CA-PAV less efficiently than PAV. Differences in tolerance to infection by three luteoviruses from California occurred in some varieties of barley and oats.