Reduction of the pesticide losses and the improvement of spray deposit through the study of the sprayer optimal air velocities in vineyard

A two years study has been carried out in order to assess spray deposits on leaves, as well as ground and drift spray losses, according to the air volumes applied, taking into account different vegetation growth stages. In the first year of experiments, trials were carried out when the vegetation was fully developed (BBCH 77), applying always a volume rate of 230 l/ha, comparing the combinations of three different forward peeds (4, 6 and 8 km/h) and four different air velocities measured on the target (4.7, 7.0, 9.7 and 13.5 m/s). In the second year of the study, the same tests were made in the vineyard at the end of flowering growth stage (BBCH 69). Results pointed out that spray deposits on the leaves increased when low air velocities (5 m/s) and reduced forward speeds (4 or 6 km/h) were adopted. The use of reduced air volumes enabled also to limit drift losses.