Two different spray application methods were compared in three vine varieties at different crop stages. A conventional spray application with a constant volume rate per unit ground area (1 ha(-1)) was compared with a variable rate application method designed to compensate electronically for measured variations in canopy dimensions. An air-blast sprayer with individual multi-nozzle spouts was fitted with three Ultrasonic sensors and three electro valves on one side, in order 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 dosing. On average, a 58% saving in application volume was achieved with the variable rate method, obtaining similar or even better leaf deposits.This work was funded by the Spanish Ministry of Education and Science, and was part of research project AGL2007-66093-C04-02/AGR. We are grateful to Professor Jordi Valero from Universitat Politècnica de Catalunya for his help in the statistical analysis and Xavier Vidal director of the School of Viticulture “Mercè Rosell” at Espiells (Barcelona) for his help during the field experiments
