The smart spray analytical system: Developing understanding of output air-assist and spray patterns from orchard sprayers

Efficient chemical application is a critical operation during specialty crop production that requires constant sprayer calibrations as well as pertinent adjustments to avoid off target spray losses. However, lack of rapid and in-field assessment tools limit the opportunities for frequent adjustments of orchard sprayer attributes. To overcome such limitations, our team has developed a smart spray analytical system (SSAS). Using SSAS, this study evaluated two commercial orchard sprayers, S1 (Powerblast 400, Rears Manufacturing Co., Eugene, OR, USA) and S2 (Turbo-Mist S30P300NSHD, Slimline Manufacturing Ltd., Penticton, BC, Canada), for their air-assist velocity and spray delivery patterns. Air-assist velocity patterns were studied in controlled conditions along two major planes: along the sprayer air-outlet (P1) and parallel to an imaginary tree row wall (P2), representing specific distances from the sprayer to tree row middles. SSAS data aided in generating several 2-D contour plots of the air-assist velocities along both the planes and for both sides of selected sprayers. Spray delivery patterns were generated along the typical locations of tree row wall and were based on pertinent air-assist velocity patterns. Results suggested that the magnitude of air-assist velocities was higher on the right side for sprayer S1 and on left side for sprayer S2. Such differences could be attributed to the design of fans, blades, rotation, air-inlet and outlet. There existed a consistent shift in air-assist along P2 plane and hence the spray delivery pattern shift on either side of both the sprayers. The uniformity in air-assist velocities decreased with the increasing distance from sprayer outlet. Average symmetries of 82.02 +/- 12.81 (standard deviation) % and 44.27 +/- 11.44% were observed in air-assist patterns for sprayer Si and S2 along the plane Pl, respectively. Similarly, average symmetries of 87.67 +/- 0.53% and 74.03 +/- 1.56% were observed in spray delivery patterns for sprayer S1 and S2, respectively. Overall, SSAS was consistent in quantification of the air-assist velocities (standard error <= 0.45 m s(-1)) and spray delivery patterns (standard error <= 0.07 ml cm(-2)) of commercial orchard sprayers and can be used at manufacturing stage for building consistent units as well as in the orchard settings for adjusting sprayer attributes to achieve targeted delivery on to the crop canopies.