BIOLOGICAL-CONTROL OF GRAPE GRAY MOLD BY TRICHODERMA-HARZIANUM

Biological and chemical control of grey mould was tested in vineyards of table and wine grapes. Treatments with Trichoderma harzianum (0.5-1.0 g l(-1)), dicarboximide fungicides (vinclozolin or iprodione) (0.5 g l(-1)) or diethofencarb plus carbendazim (0.25 g l(-1)) resulted in up to 78% disease reduction. A tank mix of the biocontrol agent with a dicarboximide fungicide was not superior to either treatment alone. It is suggested that alternate sprays of the biocontrol preparation with a fungicide should be employed in vineyards in order to reduce the use of chemicals. Populations of Trichoderma on grapes treated with the biocontrol agent were 4.5 X 10(5) per berry compared with 400-2000 per berry on untreated bunches. The application of T. harzianum in the vineyard did not interfere with processes involved in wine production from the grapes. T. harzianum and iprodione applied alone in the vineyard reduced the postharvest rot of grapes in one of two experiments. Alternation of T. harzianum with diethofencarb plus carbendazim, or its mixture with iprodione in the vineyard, resulted in a 64-68% reduction in postharvest rot caused by Botrylis cinerea.