SUMMARY
Two different spray application methods were compared in three vine varieties and different crop stages. A conventional spray application with a constant volume rate per unit ground area (loha-1) was compared with a variable rate application method designed to compensate electronically measured variations of canopy dimensions. An air-blast sprayer with individual multi-nozzle spouts was fitted up with three ultrasonic sensors and three electro-valves in one side, to modify the emitted flow rate of the nozzles according to the variability of canopy dimensions in real time. The purpose of this prototype was to precisely apply the required amount of spray liquid and avoid over and under dosing. On average, 58% savings in application volume was achieved with variable rate method, with similar or even better values of leaf deposit. In all cases the variable rate method guarantee a large number of leaves with deposits over the intended theoretical deposit threshold.