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 r
ot of grape, to assess the compatibility and possible additive effects
of selected biocontrol fungi and dicarboximide fungicides, and to det
ermine factors affecting biocontrol efficacy. In 1990, three strains o
f Trichoderma spp. were evaluated for their biocontrol ability, and al
l provided significant control of Botrytis cinerea. As few as two late
applications of the biocontrol fungi were nearly as effective as up t
o 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 foll
owed by a tank-mix application of T. harzianum and half rates of iprod
ione gave extremely effective control of bunch rot. In 1994, less effe
ctive control was obtained than in earlier years. Addition of a nutrit
ive adhesive (Pelgel, a mixture of carboxymethyl cellulose and gum ara
bic) 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 Pre
ss, Inc.