TOLERANCE TO WHITE MOLD (Sclerotinia sclerotiorum (Lib.) De Bary) IN EX RICO 23, A CULTIVAR OF WHITE BEAN(Phaseolus vulgaris L.)

Abstract

Ex Rico 23, a cultivar of white bean (Phaseolus vulgaris L.) introduced into Canada from Columbia, showed tolerance to white mold (Sclerotinia sclerotiorum) in an Ontario White Bean Variety Test at a site having severe white mold infection in 1978. Other entries, including the recommended cultivars, Fleetwood, Kentwood and Seafarer, suffered severe white mold infection and yield loss. The tolerant characteristic of Ex Rico 23 was confirmed experimentally in 1980 in both small-plot and large-scale plantings. In a field with severe white mold infection in Fleetwood, Ex Rico 23 had consistently lower disease incidence and a slower rate of disease spread. The yield loss in 1980 for Ex Rico 23 was minimal, but for Fleetwood was approximately 25 and 50% in a small-plot and a large-scale planting, respectively. The application of benomyl for disease control did not significantly increase the yield of dry beans.