Effect of Epiphytic Fungi on Brown Rot Blossom Blight and Latent Infections in Sweet Cherry

Antagonistic effects of Aureobasidium pullulans, Epicoccum purpurascens, and Gliocladium roseum on establishment of Monilinia fructicola infections on cv. Royal Anne cherry blossoms were assessed in a mist chamber and under field conditions. Conidia of each fungus were applied to blossoms that were subsequently inoculated with conidia of M. fructicola. Mist chamber experiments on forced blossoms demonstrated that incidence of recovery of M. fructicola from blossoms was significantly reduced (P ≤ 0.05) to similar levels when either E. purpurascens or the fungicide benomyl had been applied 24 h prior to inoculation with M. fructicola. In field trials in 1990, 1991, and 1993, application of E. purpurascens reduced blossom blight relative to nontreated blossoms by 47, 58, and 45%, respectively; whereas application of A. pullulans caused reductions of 54, 13, and 47%, respectively. Comparable reductions in blossom blight for the fungicide iprodione were 80, 95, and 98%, respectively. Latent M. fructicola infections were evaluated by dipping immature green cherries in a dilute solution of the herbicide paraquat. Applications of E. purpurascens and A. pullulans to blossoms reduced the number of latent M. fructicola infections in green cherries by 24 and 48%, respectively, in 1990; 57 and 62%, respectively, in 1991; and 19 and 16%, respectively, in 1993. This compares with reductions of 95, 91, and 17% in 1990, 1991, and 1993, respectively, with the fungicide iprodione. E. purpurascens and G. roseum also were recovered from surface-disinfested, paraquat-dipped cherry fruit. Percent recovery of these fungi was significantly (P ≤ 0.05) higher from treatments where they had been applied to blossoms compared with the nontreated control.