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Etiology

Alfalfa Latent Virus, a Naturally Occurring Carlavirus in Alfalfa. Venkateswarlu Veerisetty, Department of Plant Pathology, University of Nebraska, Lincoln, NB 68583, Present address of senior author: Department of Plant Pathology, University of Missouri, Columbia, MO 65201; Myron K. Brakke, Department of Plant Pathology, University of Nebraska, Lincoln, NB 68583. Phytopathology 67:1202-1206. Accepted for publication 23 March 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1202.

Alfalfa latent virus (ALV), a new member of the carlavirus group, was isolated from alfalfa (Medicago sativa) clones from the University of Nebraska experimental plots and from the farmers’ fields. The pea aphid, Acyrthosiphon pisum, transmitted this virus to M. sativa, Pisum sativum, and Vicia faba, but not to Trifolium pratense. It was also sap transmissible to V. faba, V. villosa, and P. sativum, but was not seed-borne in P. sativum. in V. faba sap ALV was infectious at 65 but not at 70 C in 10 min, or after 4 days but not after 6 days at 25 C and after dilution to 10^–3 but not 10^–4. Light microscopy indicated absence of any inclusion bodies in the epidermal strips of V. faba and P. sativum. With tobacco mosaic virus and a diffraction grating replica as standards, modal lengths of 653 and 635 nm, respectively, were determined for ALV. Serological and host range studies indicate that ALV is unrelated to pea streak virus, red clover vein mosaic virus, and cowpea mild mottle virus, other naturally occurring legume carlaviruses.