Epicoccum purpurascens for biocontrol of Sclerotinia head rot of sunflower

Epicoccum purpurascens was evaluated as a biocontrol agent of Sclerotinia h ead rot of sunflower. The potential of antifungal compounds produced by E. purpurascens as fungicides was also assayed. Treatments consisted of applic ation of E. purpurascens conidia and of partially-purified antifungal compo unds produced in broth culture before inoculation with ascospores of S. scl erotiorum. Application of conidia resulted in reduced head rot incidence on greenhouse grown plants, but the application of antifungal compounds had n o effect on head rot development. Capitula colonization by E. purpurascens had no negative effects on capitula development. After application of E. pu rpurascens to field grown plants, capitula were much less colonized than un der greenhouse conditions. As a consequence, this treatment had no effect o n head rot development in the field when plants were artificially inoculate d with S. sclerotiorum. The search for new isolates of E. purpurascens well adapted to the fluctuating conditions typical of natural environments coul d contribute to achieving an acceptable level of efficacy of this organism as a biological control agent of head rot.