Biological and integrated control of Botrytis bunch rot of grape using Trichoderma spp.

Field trials were carried out in upstate New York in 1990, 1992, 1998, and 1994 and in Chile in 1992-1993 and 1993-1994 in order to evaluate the ability of various strains of Trichoderma spp. to control bunch rot of grape, to assess the compatibility and possible additive effects of selected biocontrol fungi and dicarboximide fungicides, and to determine factors affecting biocontrol efficacy. In 1990, three strains of Trichoderma spp. were evaluated for their biocontrol ability, and all provided significant control of Botrytis cinerea. As few as two late applications of the biocontrol fungi were nearly as effective as up to five applications throughout bloom and fruit development. Trials in New York in 1992 and in Chile in 1992-1993 indicated that Trichoderma harzianum could replace some applications of iprodione or vinclozolin with little reduction in efficacy. In New York in 1993, we found that applications of T. harzianum at bloom and early fruit development followed by a tank-mix application of T. harzianum and half rates of iprodione gave extremely effective control of bunch rot. In 1994, less effective control was obtained than in earlier years. Addition of a nutritive adhesive (Pelgel, a mixture of carboxymethyl cellulose and gum arabic) applied with the biocontrol agent tended to improve results. Thus, biological control of bunch rot of grape with T. harzianum can be an effective method of management of this disease. (C) 1996 Academic Press, Inc.