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Aphid and Mechanical Transmission Properties of Bean Yellow Mosaic Virus Isolates. I. R. Evans, Graduate Assistant, Plant Pathology Department, University of Florida, Gainesville 32601, Present title and address of senior author: Assistant Professor, Department of Botany, University of Guelph, Guelph, Ontario, Canada; F. W. Zettler, Assistant Plant Pathologist, Plant Pathology Department, University of Florida, Gainesville 32601. Phytopathology 60:1170-1174. Accepted for publication 5 March 1970. DOI: 10.1094/Phyto-60-1170.

An isolate of bean yellow mosaic virus (BYMV) from Florida (FV) was compared with an isolate of BYMV from Kentucky (KV) and one from Wisconsin (WV). Although both the FV and KV proved aphid-transmissible, no transmission was obtained in parallel trials with the WV, even when a combination of different known aphid vectors and several host-plant species was used. Based on mechanical transmissibility assays and virus particle counts, however, studies showed that the nonaphid-transmissible WV occurred in a relatively higher titer in leaves than did either of the aphid-transmissible FV and KV isolates. In one experiment, pea leaves infected with the WV resulted in significantly (P = < .01) more lesions per inoculated Chenopodium amaranticolor leaf than leaves infected with the FV (510 and 129 lesions/leaf, respectively). Also, significantly (P = < .001) more particles were found in WV than FV extracts from these same infected pea leaves (10.0 and 2.1 particles/400-mesh grid square, respectively). Despite the significantly greater mechanical transmissibility and particle numbers, however, WV was not aphid-transmitted from any of these same leaves, whereas the FV was aphid-transmitted in every instance.