EFFECTS OF FOLIAR FUNGICIDE SPRAYS ON DISEASE AND YIELD OF PROCESSINGTOMATOES IN ONTARIO

The effects of controlling foliar diseases with a foliar fungicide app lied following a TOMCAST regime were evaluated on commercial processin g tomato (Lycopersicon esculentum Mill.) cultivars in three locations in Southwestern Ontario in 1990 and 199 1. For each cultivar, one set of plants was sprayed with chlorothalonil (Bravo 500) and one set rece ived no fungicide application during the growing season. At two of the three locations, fungicide application significantly reduced final fo liar disease development, averaged across all cultivars, from over 60% of the foliage infected to 10% infected. At the third location diseas e development was more restricted. Use of foliar fungicide did not res ult in a significant increase in either total fruit yield or yield of marketable fruit measured across cultivars, years, and locations. The application of fungicide (4-10 sprays) reduced the average number of f ruit infected with anthracnose by 50% over all cultivars treated. Seve ral cultivars, however, had relatively low levels of anthracnose even without fungicide sprays. While fungicide sprays may be important in m aintaining fruit quality, both with respect to solids levels and degre e of mould contamination, fungicide may not be required to maintain yi elds every year for many tomato cultivars commercially grown in Ontari o.