INCORPORATION OF WEATHER FORECASTING IN INTEGRATED, BIOLOGICAL-CHEMICAL MANAGEMENT OF BOTRYTIS-CINEREA

A strategy for integrated biological and chemical control of Botrytis cinerea in nonheated greenhouse vegetables was developed. The biocontr ol agent used was a commercial preparation developed from an isolate o f Trichoderma harzianum, T39 (Trichodex). Decisions concerning whether to spray the biocontrol agent or a fungicide were made based on a wea ther-based disease warning system. The integrated strategy (BOTMAN [sh ort for Botrytis manager]) was implemented as follows: when slow or no disease progress was expected, no spraying was needed; when an outbre ak of epidemics was expected, use of a chemical fungicide was recommen ded; in all other cases, application of T. harzianum T39 was recommend ed. Future weather information (a 4-day weather forecast provided by t he Israel Weather Forecast Service) was more useful for disease warnin gs than immediate past weather. The integrated strategy was compared w ith weekly applications of fungicide in 11 experiments conducted over 3 years in greenhouse-grown tomato and cucumber. Disease reduction in the integrated strategy (63.9 +/- 3.0%) did not differ significantly ( P < 0.05) from the fungicide-only treatment (70.1 +/- 3.6%). The numbe r of fungicide sprays in the integrated strategy ranged from 2 to 7 (m ean 4.2) compared to 7 to 13 (mean 10.5) in the fungicide treatment. T he integrated strategy averaged 5.9 sprays of T. harzianum T39. For th e integrated strategy, one treatment omitted use of T. harzianum T39 t o estimate the contribution of this agent to disease control. Disease reduction in that treatment (49.1 +/- 4.8%) was significantly (P < 0.0 5) inferior to the combined chemical and biological strategy, indicati ng that the harzianum T39 sprays had a measurable effect on disease co ntrol.