Environmental Evaluation of Vineyard Airblast Sprayers Through a Comprehensive Spray Mass-Balance Approach

The efficacy and sustainability of pesticide application largely depends on maximizing target coverage, while minimizing off-target losses. It derives that the sprayer efficiency plays a key role for a more sustainable agriculture. The evaluation of sprayer efficiency must consider not only spray off-target losses but also the canopy deposition for a comprehensive assessment. For these purposes an ad hoc method designed for the spray mass-balance measurements was applied. Tests were conducted in a vineyard at early and late growth stages, to evaluate the efficiency of two airblast sprayers (conventional vs tower shaped) and the effect of different spray volume rates (conventional full volume vs halved volume) on the efficiency of spray application. For these purposes a spray mass-balance trial layout was used. It consists in sampling the three main spray fractions: i) canopy deposition, ii) ground losses and iii) airborne spray losses, thanks to a frame arch surrounding the sprayed rows and used to hold the collectors exposed to the atmosphere. Results underline the effect of sprayer type on the spray application efficiency and that also in the best cases at early growth stage no more than 13% of spray mixture is retained by canopies. Concurrently the reduction of applied volume had no negative effect on spray application efficiency as the ratio between canopy deposition and off-target losses did not vary when compared with the full volume. It can be concluded that the spray application efficiency largely depends on technical factors mainly related to the sprayer design and its adjustment and to the target morphological characteristics.