Resistant Alfalfa Plants as Symptomless Carriers of Verticillium albo-atrum. Barbara W. Pennypacker, Research Associate, Department of Plant Pathology, The Pennsylvania State University. K. T. Leath, Research Plant Pathologist, and R. R. Hill, Jr., Research Agronomist, U.S. Regional Pasture Research Laboratory, University Park, PA 16802. Plant Dis. 69:510-511. Accepted for publication 3 December 1984. 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, 1985. DOI: 10.1094/PD-69-510.

Alfalfa cultivars resistant and susceptible to Verticillium wilt were grown in the greenhouse, stubble-inoculated with Verticillium albo-atrum, and evaluated for percentage of symptomless plants. Distribution of symptomless plants was: Vertus, 54%; NAPB 108, 54%; NAPB 110, 47.5%; Apollo II, 36%; CW8015, 36%; WL 316, 35%; Cimmaron, 22.5%; and Saranac AR, 10%. Symptomless plants in all cultivars except in NAPB 108 95% were positive for V. albo-atrum when the stem bases were cultured 7 mo after inoculation. A high percentage of plants in resistant cultivars have the potential of serving as symptomless carriers of the pathogen.

Keyword(s): Medicago sativa.