Leaf removal time and its effect on the chemical composition of Chardonnay and Cabernet-Sauvignon musts and the composition and quality of wines in Cauquenes, Chile.

In Chile, leaf removal is a recommended practice for many Chilean vineyards. It is suggested that it promotes better illumination and ventilation for the fruit, facilitates spraying of chemicals and harvesting, and that it enhances color in black grapes. As well, it diminishes the herbaceous flavor in wine cultivars, and results in a better general wine quality. Nevertheless, if not mechanized, it is slow and expensive work. In the 1992/93 season at the interior dryland of Cauquenes, Chile, a field trial to evaluate the effects of defoliation before set, before veraison and after veraison, was performed on commercial vineyards of Chardonnay and Cabernet-Sauvignon. About 60% of the leaves in the bunch zone were eliminated. Musts and wines were chemically analyzed and sensory evaluated. Results showed some differences in some components, but they were erratic and of high variability. In the sensory evaluation, for both cultivars, it was only possible to differentiate the wines from the non-defoliated vines, but not the effect of the time of defoliation. It was not possible to determine the causes of the differences, or to attribute the changes to the levels of the analyzed compounds