LAUSR

BACKGROUND Aerial spray is one of the most important applications of unmanned aerial vehicle (UAV) in agriculture. This work aimed to promote the use of UAVs as an alternative to knapsack electric sprayers in pesticide application in Nanguo pear orchards which planted in mountain terraced orchard scenarios. The spray deposition of four types of nozzles (SX110015, XR80015, IDK90015 and TR80015), two spray volume rates (45 L·ha-1 , 90 L·ha-1 ) and with or without a commercial surfactant adjuvant were evaluated based on the Spot Spray mode. RESULTS The nozzle IDK90015 equipped with air-assisted showed significantly higher deposition and penetration, its large droplet size also reduced the risk of drift. Increasing the spray volume rate can increase the amount of droplets deposition. Adjuvant showed excellent potential to improve spray technology in Nanguo pear trees with the mean deposition of 0.175 to 0.574 μL·cm-2 and penetration of 3.09% to 66.73%, the droplet size also increased significantly with volume median diameter (DV0.5 ) of 469 μm. CONCLUSION The nozzle type, spray volume rate and adjuvant should be well considered when using the Spot Spray in orchard. Compared with increasing spray volume rate, the use of air-induction nozzles and surfactant-based adjuvants can improve the spray deposition better.