Control of Grapevine Grey Mould with Trichoderma harzianum T39

The efficacy of a formulation of Trichoderma harzianum T39 for control of grey mould (Botrytis cinerea) on grapevine was examined in 133 experiments conducted under diverse commercial conditions. The experiments were carried out between 1988 and 1994 in 19 countries and on 34 varieties. The average disease incidence in the untreated plots of all experiments was 42 2.3% (mean standard error). In general, the reduction of disease achieved by T. harzianum application was lower than that obtained by chemical fungicides: 36.3 2.7% disease reduction in biocontrol treatments and 52.3 2.6% in the exclusively chemical treatments. Control efficacy declined when the interval between application and assessment dates increased to 5 weeks. The experiments also included treatments in which T. harzianum was integrated with chemical fungicides, the two being applied alternately, and a reduced chemical treatment in which only chemicals were applied, and only at the times when chemicals were applied in the integrated treatment. The mean control efficacy in these treatments was 55.8 3.2% and 44.2 4.9% respectively. The roles of the integration of biological and chemical compounds in reducing pesticide residues in fruit at harvest and lowering the pressure towards development of fungicide-resistance populations of B. cinerea are discussed.