Effects of prototype air deflector and spray unit on pesticide canopy distribution uniformity and drift in vineyards

A prototype air deflector and spraying unit hanged on conventional air-assisted orchard sprayer was used to make applications to the outside row of a trellis vineyard. Fluorescent tracer dye was applied by using hollow cone nozzles with 1.2 mm diameter orifice. Experiments were conducted at three levels of spraying pressure, which were 6, 12 and 18 bar, and three levels of air flow rates, which were 24,830, 30,473 and 36,117 m 3 h -1 . During the experiments, canopy distribution uniformity, coverage, downwind sedimentation and airborne drift were measured from 16 locations by using water- sensitive papers and filter papers. Treatment with air deflector and spraying unit at 6 bar pressure and 30,473 m 3 h -1 air flow rate produced the most uniform canopy distribution (CV = 6.24%). Although treatment with 18 bar provided the highest average deposit on the canopy samples, the difference between these two treatments was not significant. Generally, increasing of pressure and air flow rate increased the coverage on the canopy, but the differences among all treatments were found not significant statistically. One of the lowest sedimentation on ground was measured at the treatment with 6 bar pressure and 30,473 m 3 h -1 air flow rate. The conventional air-assisted sprayer produced worse deposits, coverage and canopy distribution uniformity than the unit. Additionally, the conventional air-assisted sprayer produced higher ground sedimentation and airborne drift than the treatment with air deflector and spraying unit at 6 bar pressure and 30,473 m 3 h -1 air flow rate conditions. Therefore, instead of conventional air-assisted sprayer, use of air deflector and spraying unit is suggested to achieve better application results.