Barley Yellow Dwarf Viruses in Small Grains of Pennsylvania: Isolate Identification, Distribution, and Vector Efficiency. F. E. Gildow, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. J. Frank, D. Bingaman, and C. Powell. Department of Plant Pathology, The Pennsylvania State University, University Park 16802, and Bureau of Plant Industry, Pennsylvania Department of Agriculture, Harrisburg 17110. Plant Dis. 71:922-926. Accepted for publication 19 February 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0922.

Barley yellow dwarf virus (BYDV) was identified in small grains collected from 1984 to 1986 from eight counties in Pennsylvania. Isolates of BYDV recovered from commercial fields in three environmentally distinct cereal management areas were compared with the four characterized New York isolates (RPV, RMV, MAV, and PAV) by a combination of enzyme-linked immunosorbent assay and aphid transmission specificity. BYDV was recovered from 300 of 376 plants selected for testing on the basis of symptom expression. Sixteen percent of the BYDV-positive plants were infected by more than one isolate of BYDV. Data combined from single and mixed infections indicate that the percentages of plants infected with isolates resembling RPV, RMV, MAV, and PAV were 19, 4, 9, and 82%, respectively. Isolates similar to SGV were not detected in this survey. Comparisons of two Rhopalosiphum padi aphid clones and five Sitobion avenae aphid clones collected in Pennsylvania with previously characterized clones of New York aphids indicated no differences in vector specificity for the four BYDV isolate types. Of the 329 R. padi and S. avenae collected from symptomless oat plants from fields in three counties, 15 were viruliferous for PAV, 1 for RPV, and 1 for MAV. Results suggest reservoirs for a variety of BYDV isolates occur throughout Pennsylvania and that future epiphytotics could occur under the appropriate environmental conditions.