Disease Note

First Report of RMV-Type Barley Yellow Dwarf Virus in Barley in Eastern Washington. S. E. Halbert, University of Idaho, Southwest Idaho Research and Extension Center, Parma 83660. K. S. Pike, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser 99350. Plant Dis. 70:475. Accepted for publication 16 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-475d.

Four isolates of barley yellow dwarf virus (BYDV) obtained from Rhopalosiphum maidis (Fitch) on barley (Hordeum vulgare L.) in Prosser, Washington, were confirmed to be RMV types (transmitted specifically by R. maidis) through aphid transmission assays. The isolates were transmitted consistently by R. maidis and occasionally by R. padi (L.). The presence of RMV was confirmed serologically by W. F. Rochow. Other workers have reported only PAV-type (nonspecifically transmitted) BYDV in eastern Washington. In previous years, local isolates were transmitted frequently by R. padi, Metopolophium dirhodum (Walker), and Sitobion avenae (Fabricius) but only rarely by R. maidis. In autumn 1984, however, R. maidis collected from barley transmitted BYDV more frequently than did R. padi taken from the same crop. The RMV isolate could cause damage to barley in years when R. maidis is abundant but is not likely to threaten wheat because the local biotype of R. maidis rarely infests wheat.