Barley Yellow Dwarf Luteoviruses in Montana Cereals. D. J. Yount, Former Graduate Research Assistant, Department of Plant Pathology, Montana State University, Bozeman 59717. T. W. Carroll, Professor, Department of Plant Pathology, Montana State University, Bozeman 59717. Plant Dis. 67:1217-1222. Accepted for publication 6 May 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1217.

From 1978 through 1981, leaf samples of small grains and native aphid populations collected from 10 counties in central Montana were tested for barley yellow dwarf luteoviruses (BYD-LV) by aphid transmission and enzyme immunosorbent assay (EIA). Montana isolates were similar in most respects to the PAV, MAV (SAV), RMV, and RPV luteoviruses previously characterized in New York. Montana RMV types, however, failed to react in EIA tests using New York RMV immunoglobulin. Montana BYD-LV similar to PAV were the most prevalent and most virulent among the BYD-LV isolated. Barley yellow dwarf (BYD) disease appeared to be most important in fall-seeded winter wheat when large viruliferous aphid populations were present. In 1980 and 1981, two epiphytotics of BYD occurred in winter wheat as a result of early seeding and moderate temperatures during September and October that favored vector population increases. Planting winter wheat after 10 September appears to be an effective control measure for avoiding serious losses from BYD in Montana.