Barley Yellow Dwarf Virus in Pennsylvania: Effect of the PAV Isolate on Yield Components of Noble Spring Oats. F. E. Gildow, Assistant Professor of Plant Pathology, USDA-ARS, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. J. A. Frank, Research Plant Pathologist, USDA-ARS, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Plant Dis. 72:254-256. Accepted for publication 11 October 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0254.

The effect of a single inoculation of Noble spring oats with the PAV isolate of barley yellow dwarf virus (BYDV) at either 4 or 6 wk after planting was evaluated in field trials in Pennsylvania. The virus was transmitted to the plants by the aphid Rhopalosiphum padi. In 1985, the number of heads per meter, number of seeds per head, thousand kernel weight (TKW), and overall yield were reduced by inoculation at 6 wk after planting. These components, except for the TKW, were reduced further when inoculation was made at 4 wk. In 1986, the greatest yield reduction occurred with the 6-wk inoculation, with a reduction in all yield components. Although a cold period during the aphid inoculation access period reduced the effectiveness of the inoculation at 4 wk, the overall plot yield was still less than that for the control. These data indicate levels of yield loss that could result from infections of some oat cultivars under field conditions with PAV-like isolates and substantiate the significance of early infections with BYDV.