Pathogenicity of an Isolate of Verticillium dahliae from Barley. D. E. Mathre, Department of Plant Pathology, Montana State University, Bozeman 59717. . Plant Dis. 73:164-167. Accepted for publication 30 October 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0164.

A fungus isolated from leaves of barley was determined to be Verticillium dahliae. Its pathogenicity was compared with that of known isolates of this fungus from tomatoes, cotton, and potatoes, and with members of various vegetative compatibility groups. Among small grain cereals, oats and barley were susceptible. Wheat was infected but did not develop severe symptoms. Wounding of roots facilitated infection, but was not required. Symptoms on infected oats and barley included chlorosis of leaves, usually in stripes along the leaf margin, followed by necrosis. The isolate originating from barley was similar in pathogenicity to isolates from potatoes or potato soil. Even V. albo-atrum from alfalfa was capable of infecting oats and causing slight symptoms. Within barley, there were differences in susceptibility between the various cultivars tested, ranging from highly susceptible to resistant.