Effect of culture filtrate of Curvularia inaequalis on disease control and productivity of grape cv. Isabel

This study aimed to evaluate the effect of a culture filtrate of the saprophytic fungus Curvularia inaequalis on the control of the foliar diseases downy mildew and isariopsis leaf spot of grapevine and on the incidence and severity of grape fruit mildew under field conditions. This study also analyzed the physical and physicochemical characteristics of fruits that were treated preharvest during standard season production and off season production. Concentrations of 0 (absolute control), 1, 5, 10 and 20 ml L-1 culture filtrate were tested. The standard treatments that were used as controls were bordeaux mixture, mancozeb, acibenzolar-S-methyl and Agaricus blazei. In the case of downy mildew, the concentrations reached a control of approximately 56% compared to that of the absolute control treatment during both seasons. The reduction of the isariopsis leaf spot was approximately 54 and 42% in the standard season and off season, respectively. The severity of fruit mildew was controlled in 62% of the cases, but the incidence was controlled in approximately 11% of the cases. Postharvest, the pH and relationship between solids and acidity (TSS/TTA) of the fruit pulp remained in the ideal range, the fruits showed low juice yield and high total titratable acidity, and the bunch weight, number of bunches and yield per plant were higher in the off season than in standard season and were affected by weather conditions and the pruning season.   Key words: Vitis labrusca, biological control, agro-ecology, organic production.