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Variants of Barley Yellow Dwarf Virus Collected in New York and Illinois. W. F. Rochow, Research Plant Pathologist, Crops Research Division, ARS, USDA, and Professor of Plant Pathology, Cornell University, Ithaca, New York 14850; H. Jedlinski, Research Plant Pathologist, Crops Research Division, ARS, USDA, and Assistant Professor, Department of Plant Pathology, University of Illinois, Urbana, Illinois 61801. Phytopathology 60:1030-1035. Accepted for publication 2 February 1970. DOI: 10.1094/Phyto-60-1030.

All 367 isolates of barley yellow dwarf virus recovered from 372 samples collected in the field during 1967 and 1968 could be grouped among the four major variants previously encountered. These are RPV, RMV, and MAV transmitted specifically by Rhopalosiphum padi, R. maidis, and Macrosiphum avenae, respectively, and PAV transmitted nonspecifically by R. padi and M. avenae. Parallel tests on samples of spring oats from New York and Illinois showed that all four variants occurred in both areas, but their prevalence was different. For 148 isolates from Illinois, the distribution of variants was the same in both seasons. About 75% of the isolates were like PAV, about 20% like RPV, a single one each year was like RMV, and a single isolate (in 1967) like MAV. The 76 isolates recovered from New York samples in 1967 were distributed about as follows: 46% PAV, 36% MAV, 10% RPV, and 8% RMV. The 54 New York isolates identified in 1968 were 28% PAV, 61% MAV, 6% RPV, and 6% RMV. Five of 16 winter wheat plants and 15 of 55 winter barley plants collected in New York were found to be infected by more than one of the variants. The distribution patterns of the isolates at the two locations and the mixed infections in winter cereals are considered relevant to epidemiology of the disease.