Ulocladium afrum as a biological control agent for white mold of bean caused by Sclerotinia sclerotiorum

Field studies were conducted near Lethbridge, Alberta, Canada, in 2001, 2004 and 2005 to determine the efficacy of the antagonistic fungus Ulocladium atrum for control of white mold of bean caused by Sclerotinia sclerotiorum. Results of the 3 years of field trials showed that, compared with the untreated control, foliar application of a spore suspension of U. atrum (300 Ml M-2 of 10(6) spores ml(-1) suspension) significantly reduced incidence and severity of white mold, increased seed yield and reduced contamination of bean seed by sclerotia of S. sclerotiorum. The level of control of white mold observed in the treatment of U. atrum was similar to that of the mycoparasitic fungus Coniothyrium minitans, but lower than the fungicide treatments of Ronilan (vinclozolin) at the rate of 1200 g ha(-1) per application in 2001, or Lance (boscalid) at the rate of 750 g ha(-1) per application in 2004 and 2005. The potential for use of U. atrum as a biological control agent for sclerotinia diseases is discussed. KEY WORDS: Antagonism; common bean; biological control; Phaseolus vulgaris; Sclerotinia sclerotiorum; Ulocladium atrum; white mold.