Preliminary evaluation of irrigator emitters for pesticide application through solid set canopy delivering system in apple orchard and vineyard

Recently, valuable alternatives to conventional pesticide application equipment are under investigation in 3D crops for improving pesticide spray application efficiency. Customized solid set canopy delivery systems (SSCDSs), tested in apple orchard and vineyard showed potential to reduce plant protection products (PPPs) spray drift while guaranteeing adequate spray deposition on the target and biological efficacy. Based on these premises, this study evaluated the feasibility to use a flat fan pulsed emitter (StripNet® - Netafim), usually installed in orchard and vineyard for irrigation and frost/heat-stress damage mitigation purposes, also to perform PPP spray applications. Laboratory tests were made to characterize the emitter flow rate at different pressures and the droplet size spectra generated. Semi-field trials were then carried out to measure StripNet® spray coverage in semi-pedestrian trained trellised apple orchard and Guyot espalier trained trellised vineyard. The performance of StripNet® flat fan emitter was evaluated comparing the spray coverage obtained with the one achieved using conventional sprayers equipped with spray drift reducing technology (SDRT), both in apple orchard and vineyard. StripNet® emitter was characterized by a VMD value of 453.1 µm and 4.60% of V100 indicating potential in reducing spray drift. Semi-field trials indicated differences between crops in terms of spray coverage attributable to the canopy shape and density, with higher homogeneity at all canopy height and depth in apple orchard case. In vineyard, a high spray coverage was observed on the top of the canopy, while lower values were registered in the medium and lower parts of the rows, thus affecting the overall uniformity of spray distribution. The use of StripNet® for PPPs application from the top of the canopy resulted therefore a feasible option in apple orchard, while for vineyard further studies are necessary to define the type of emitter and its position into the canopy able to guarantee the necessary uniformity of the deposition along the canopy structure.