Mahoney, K. J., McCreary, C. M. and Gillard, C. L. 2014. Response of dry bean white mould [Sclerotinia sclerotiorum(Lib.) de Bary, causal organism] to fungicides. Can. J. Plant Sci. 94: 905-910. White mould [Sclerotinia sclerotiorum (Lib.) de Bary, causal organism] is a serious disease of dry bean (Phaseolus vulgaris L.). Producers frequently rely on preventative fungicides, yet, this represents a significant production cost. Studies were conducted in 2009, 2010, and 2011 to determine fungicide efficacy under conditions optimized for white mould. Disease incidence×severity ratings were used to calculate the area under the disease progress curve (AUDPC). After harvest, a return on investment (ROI) was calculated. AUDPC values were similar across boscalid, fluazinam, fluopyram, and thiophanate-methyl and lower than Bacillus subtilis, CaCl₂, and the untreated. Yield was greatest for fluazinam and fluopyram, followed by thiophanate-methyl. Bacillus subtilis and CaCl₂ yields were similar to the untreated. In early-planted environments, using fluazinam and fluopyram resulted in a $500 ha^-1 greater ROI than the untreated with $554 gained for every tonne per hectare of dry bean harvested. In late-planted environments, fluazinam and fluopyram averaged about $200 ha^-1 greater ROI than the untreated and $494 was returned for every tonne per hectare of dry bean. When dry bean yield potential is reduced under conditions of increased white mould severity, profit margins become narrowed and producers may have to select fungicides that are both efficacious and economical.