Effect of UAV prewetting application during the flowering period of cotton on pesticide droplet deposition

Abstract

Prewetting process can reduce the contact angle between the droplet and the leaf blade, so that the droplet can more easily wet and spread, thereby increasing the quantity of deposition. To improve the effectiveness of pesticides on cotton leaves, prewetting by single-rotor electric unmanned aerial vehicles (UAV) was studied, focusing on the effects of pesticide deposition on cotton leaves during the flowering period. Cotton leaves in 0°-30°, 30°-60°, 60°-90°leaf blade angle ranges (angle between the leaf blade and the horizontal plane) were examined. In the first experiment, four different prewetting volumes (0, 1.6, 3.2 and 4.8 L) were sprayed by a singlerotor electric UAV on four cotton plots (plots A-D) each with an area of 120 m 2 , and then each area was sprayed with a 0.8% (w/v) ponceau 2R solution by another singlerotor electric UAV. The results revealed that with no prewetting, droplet deposition quantity decreased with increasing leaf blade inclination. After prewetting, the mean droplet deposition quantity on plots B, C and D increased by 39.8%, 9.7% and 24.9%, respectively. The prewetting rate of 1.6 L per 120 m 2 had the most significant effect on improving the deposition of droplets. It was also found that the mean droplet deposition quantity in each leaf blade angle range increased after prewetting. For the leaf blade angle range 60°-90°, this increase was the most pronounced, with 0.043, 0.062, 0.057 and 0.048 mL$cm -2 in plots A-D, respectively. Also, droplet deposition uniformity in the leaf blade angle range 60°-90°was better after prewetting. These results should provide a valuable reference for future research and practice to improve the effectiveness of pesticides applied to cotton by aerial applications.

Research on Methods Decreasing Pesticide Waste Based on Plant Protection Unmanned Aerial Vehicles: A Review

“…The UAV provides GPS positioning and the motorboat is used for weeding in paddy fields, avoiding the problem of pesticides drifting in the air. A pre-wetting process can reduce the contact angle between the droplet and the blade, making it easier for the droplet to wet and spread, thereby increasing the amount of deposition and improving efficiency ( Yao et al, 2018 ). Dicamba hydrogel was added to the chemical solution to increase the deposition of the chemical solution and reduce the environmental pollution caused by the drift of pesticide spray ( Song et al, 2021 ).…”

Spray performance and control efficacy against pests in paddy rice by UAV‐based pesticide application: effects of atomization, UAV configuration and flight velocity

“…The primary targets of these UAV sprayers are pervasive pests and diseases such as corn borer, rice fly, rice leaf roller, rice blight, aphids, and wheat powdery mildew. [18][19][20][21][22][23][24][25] Research on unmanned aerial plant protection primarily focuses on major staple crops, including rice, wheat, corn, and cotton. Among these, rice has been the subject of more extensive research.…”

“…This advancement is evident in a variety of agricultural settings including rice, wheat, corn, cotton, and fruit orchards. The primary targets of these UAV sprayers are pervasive pests and diseases such as corn borer, rice fly, rice leaf roller, rice blight, aphids, and wheat powdery mildew 18–25 . Research on unmanned aerial plant protection primarily focuses on major staple crops, including rice, wheat, corn, and cotton.…”

Droplet Size Distribution Characteristics of Aerial Nozzles by Bell206L4 Helicopter under Medium and Low Airflow Velocity Wind Tunnel Conditions and Field Verification Test

“…Aerial application, a spraying method with aircraft as the application platform, is one of the most important contents of precision agricultural aviation. Compared with ground machinery, aviation spraying has the advantages of high operating efficiency, a large area of prevention, good control effect, and strong response-ability to a sudden outbreak of pests [1,2]. The essence of aerial applications is the movement process of pesticide after being atomized into small droplets and then settled to the target crop for pest control.…”