Submitted to: Smart Agricultural Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2025
Publication Date: 6/30/2025
Citation: Herkins, M., Hong, S., Zhao, L., Zhu, H., Jeon, H. 2025. Computer simulation of pesticide deposition and drift by conventional and intelligent air-assisted sprayers in apple orchards. Smart Agricultural Technology. 12. Article 101111. https://doi.org/10.1016/j.atech.2025.101111.
DOI: https://doi.org/10.1016/j.atech.2025.101111

Interpretive Summary: Optimized amount of spray deposition on crops can maximize pesticide application effectiveness and minimize pesticide waste. However, field measurements of spray deposition is costly and time intensive due to large variabilities in uncontrollable weather conditions and crop characteristics. To address this challenge, a computer program was developed and validated with a computational fluid dynamics simulation database as a complementary approach to field assessments. With the program, spray deposition inside crop canopies was determined to optimize spray parameters of conventional and intelligent sprayers in apple orchards. Computer simulations demonstrated that canopy deposition varied highly with the growth stage, nozzle type, and wind speed. Nozzles producing droplet sizes between 100 and 300 µm were found to achieve the maximum canopy deposition in all growth stages. Especially at later growth stages when foliage was fully developed, nozzles that produced droplets of approximately 100 µm could lead to increased canopy deposition when wind speed was 2 miles per hour and ambient temperature was 86°F. Under the same conditions, conventional and intelligent sprayers produced comparable canopy deposition while the intelligent sprayer reduced spray volume by 38.4% to 51.9%. The computer program would be a useful tool for pesticide applicators to select proper spray parameters to obtain maximal pesticide application efficiency in orchard applications.

Technical Abstract: Optimizing pesticide sprayers is essential to reduce chemical costs and environmental health risks associated with pesticide applications. To enhance sprayer performance, a laser-guided intelligent spraying system was developed to deliver variable-rate spray outputs tailored to different sections of a tree canopy. However, verifying the effectiveness of this system through extensive field measurements is challenging and resource-intensive due to the variability of spray dynamics and environmental conditions. In this study, computational fluid dynamics (CFD) simulations using a user-friendly computer program called the Simulation of Air-Assisted Sprayers (SAAS) were conducted to evaluate pesticide deposition in apple orchards, offering a controlled, cost-effective alternative to field experiments. Results indicated that pesticide deposition efficiency was highest when very fine spray nozzles were used under conditions of low wind speeds, low relative humidity, and moderate temperatures at later growth stages. Compared to a conventional spray system, the intelligent spraying system reduced pesticide usage by 38.4% to 51.9% and improved spray efficiency by 64.1% to 229.2%, depending on the nozzle type. Among all tested conditions, the highest canopy deposition occurred with a very fine nozzle at a wind speed of 0.89 m s'¹ on a full-foliage crop. This research demonstrates the potential of CFD simulations using the SAAS tool to optimize pesticide applications, improving spray efficiency while reducing environmental impact.