Components of Resistance to Rhizoctonia solani Associated with Two Tall Fescue Cultivars

Components of resistance to Rhizoctonia solani in the tall fescue cultivars Kentucky 31 (moderately resistant) and Mojave (susceptible) were evaluated under controlled environmental conditions. Size and expansion rate of foliar lesions were recorded on 100 individual plants of each cultivar. Lesions on the first fully expanded leaves of 6- to 10-month-old inoculated plants covered a significantly greater proportion of the leaf width on cv. Mojave compared to Kentucky 31. Rate of lesion expansion was also greater on cv. Mojave than on Kentucky 31. Lesion size and rate of expansion were greater on the second compared to the first fully expanded leaf of both cultivars. Wider leaves and slower lesion expansion are two components responsible for the greater level of resistance to R. solani in cv. Kentucky 31 compared to Mojave tall fescue.