Effets de l’application d’acide gibbérellique (GA3) sur la qualité de raisins et de vins produits en climat tropical au Nord-Est du Brésil

The honeydew moth Cryptoblabes gnidiella is the main problem for the wineries in the Northeast of the Brazil, because it attacks the bunch and reduces the quality of the grapes and the wines. In order to stretch out the bunch to facilitate the penetration of the insecticides, it was used gibberellic acid. Six treatments with different concentrations and different dates of application, and the control were compared. The bunches are compact, characteristic of the « Syrah » grapes in this region. The grape berries were analysed at harvest and wines were made by microvinifications. The grape berries showed different qualitative characteristics, as berry weight, number of berries, ºBrix, total acidity and heterogeneity of the maturation. The microvinifications were carried out with 50 kg of grapeberries into glass bottles of 20 L at 22ºC, for the alcoholic and malolactic fermentations, then stabilized and bottled. The wines were tasted by a panel of ten people and compared on smell and taste plans. The tasting results showed that the control treatment was the best graded wine. The application of gibberellic acid allowed to control the honeydew moth attack, but it caused a heterogeneity on grape maturation, with a lower quality of the grapes and wines compared to the control.