Sclerotinia control in irrigated dry bean

Abstract

White mold, caused by Sclerotinia sclerotiorum, can devastate an irrigated dry bean (Phaseolus vulgaris L.) crop. The fungal infection begins on the petals when the weather is cool and damp and the microclimate within the crop canopy remains humid. Sclerotinia infection can be reduced by an application of fungicide on the bean petals before the infection begins. Because leaves shield the flowers on dry bean plants, conventional field sprayers may not be the most effective method of applying fungicide. A three year project involving a network of cooperating farmers was conducted to compare the skid-boom and airblast sprayers to conventional sprayers for effectiveness of fungicide application. Effectiveness was measured by the number of Sclerotinia infected plants and yield of irrigated dry bean. Differences in yield and infection incidence among sprayer types were not significant. Yield and infection incidence differences among years were significant. The decision to apply fungicide for Sclerotinia control in irrigated dry bean in south-central Saskatchewan depends on the probability of cool, moist weather occurring during the flowering period.