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Natural Hosts and Vectors of Tobacco Streak Virus in Eastern Washington. Walter J. Kaiser, Research plant pathologist, Regional Plant Introduction Station, Washington State University, Pullman 99164; Stephen D. Wyatt(2), and George R. Pesho(3). (2)Assistant professor, Department of Plant Pathology, Washington State University, Pullman 99164; (3)Research entomologist, Regional Plant Introduction Station, Washington State University, Pullman 99164. Phytopathology 72:1508-1512. Accepted for publication 11 June 1982. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982.. DOI: 10.1094/Phyto-72-1508.

Tobacco streak virus (TSV) was isolated from naturally infected white sweet clover (Melilotus alba) and cowpea (Vigna unguiculata), but not from other wild plant species at Central Ferry, WA. M. alba, a biennial wild legume, was the primary reservoir and overwintering host of TSV in this region of eastern Washington. The virus was seedborne in 0.7–90.6% of the seed of five artificially infected plant species and in <3% of the seed of naturally infected M. alba plants. Tobacco streak virus was symptomless in naturally or artificially infected M. alba. Five isolates of the virus from cowpea (C1, C2) and white sweet clover (M1, M2, M3) were divided into two pathotypes, I (isolates C1, C2, M1) and II (isolates M2, M3), on the basis of symptoms produced on several inoculated hosts, particularly Chenopodium quinoa, Phaseolus vulgaris ‘Bountiful,’ and Vicia faba, and reactions in immunodiffusion tests with TSV antisera from four sources. The two pathotypes appeared to belong to distinct serotypes. Studies of TSV transmission by insect vectors demonstrated that TSV was transmitted from naturally infected M. alba to C. quinoa and M. alba by thrips (Thrips tabaci and/or Frankliniella occidentalis), but not by pea aphids (Acyrthosiphon pisum) or pea leaf weevils (Sitona lineata).

Additional keywords: virus transmission by thrips.