Field validation of dosaviña, a decision support system to determine the optimal volume rate for pesticide application in vineyards

Dose expression and volume rate are key questions for spray application in orchard and vineyard plantations. Crop characteristics seem to be one of the most important factors to determine the optimal value, but parameters as the leaf area, canopy volume, and canopy density are difficult to quantify. dosaviña, a decision support system, has been developed as a tool to calculate the optimal volume rate for spray applications in vineyards. The method is based on achieving the optimal coverage (impactscm⁻²) according to the characteristics of the crop canopy, and includes the establishment of an efficiency factor that depends on aspects such as the type of sprayer used, nozzle type and size, operational parameters, and weather conditions. Field tests, in order to evaluate the interest in and functionality of the dosaviña computer program, were arranged for different wine grape varieties in New York State (USA) and Lleida (Spain), with a wide spectrum of wine varieties (Baco, Riesling, Vignoles, Merlot, and Cabernet Sauvignon), sprayers, and working conditions. Deposition, uniformity, and control of different diseases (powdery mildew, Botrytis bunch rot, and grape black rot) were evaluated at different crop stages, by comparing the volume rate applied according to dosaviña with the conventional rate most generally used by farmers. The volume rate was reduced by an average 39.9% for dosaviña, with similar or even higher values of deposition and uniformity. The resulting reduction in pesticide use (average 53%) did not present any difference in disease control for the selected varieties. Methodologies based on coverage and leaf area, as prescribed by dosaviña, seem to be an effective alternative approach to determine the most adequate volume rate according to the canopy structure, with the consequent diminution of pesticide use and the increase of environmentally friendly practices.