Vineyard Cover Spraying Evaluation According to Plant Vigour Variations

Abstract

The most important goal of pesticide application in agriculture is to get uniform distribution of chemicals throughout the canopy. Under dosage may not give the desired coverage and control needed. Over dosage is expensive as it wastes pesticide and increases the potential for groundwater contamination. New sprayer technologies are needed in order to optimize plant spraying and reduce environmental impact. A conventional low dosage (~85 L ha^-1) pneumatic sprayer was used in order to evaluate spraying quality taking in consideration different vineyard vegetation vigour. The data were collected under field operating conditions using water sensitive papers. The papers were positioned at three levels on the crop for each treatment. Each water sensitive paper was analysed using the DepositScan software system. Statistics were reported for Volume Median Diameter (VMD), droplet cover and the ratio between spray volume and leaf volume (L m^-3).
Results show that droplet cover goes from 0 % to 30 % with a coefficient of variation normally above 80 %; droplet VMD goes from ~100 μm to ~500 μm and the ratio between spray volume and leaf volume goes from 0.02 L m^-3 to 0.32 L m^-3. These huge variations happen because there are no fast and flexible systems reacting to site-specific needs without destroying the quality of spraying. Considering the previous there is a need of smart spraying systems and because of that the CARTS (Canopy Adjusted Real Time Spraying) project was setup and was initiated in November 2015. The main objective of the CARTS project is to produce a spray equipment with capacity to measure the volume of leaves and adjust, in real time, the spray volume rate to be applied. To achieve this goal, the CARTS project brought together the Hexastep (Business leader: hexastep.pt), the University of Évora (Scientific leader: uevora.pt) and Micron (industrial leader: microngroup.com).