Multi-objective pesticide reduction-oriented design optimization, atomization-deposition performance and pests control efficacy of air-assisted sprayers for dense-planting spindle and V-trellis pear orchards.

BACKGROUND: High-density spindle and V-trellis pear orchards face critical bottlenecks including complex canopies, poor sprayer adaptability, insufficient droplet penetration, uneven deposition, and low pesticide utilization. To overcome these issues, this study established a systematic framework including structure adaptation, parameter optimization, mechanism analysis, performance validation, and multi-objective evaluation. A dedicated air-assisted sprayer was developed using modular design, computational fluid dynamics (CFD) simulation, intelligent target detection, and high-speed flow-field visualization. The spray characteristics, air-droplet coupling, and operational parameters were optimized and verified in laboratory and field tests.

RESULTS: The plant-derived adjuvant decreased surface tension to 54.23 mN m-1 and contact angle to 49.68°, improving wetting and deposition significantly. The optimal system (60° deflector, 2200 rpm fan, 0.3 MPa pressure) produced stable wind speeds of 4.48-6.08 m s-1 and uniform droplets with a relative span < 1.1. Field deposition reached 3.82 μL cm-2 (V-trellis) and 2.79 μL cm-2 (spindle). Control efficacy against major pests improved from 19-49.74% (1 day after treatment) to 39.91-72.41% (3 days after treatment). The optimized system reduced pesticide dosage by 25% while maintaining equivalent or better efficacy, with stabilized control up to 77.38%.

CONCLUSION: This study resolves the poor adaptability of conventional sprayers, reveals the air-droplet coupling transport mechanism, and provides a technical scheme for precision green plant protection in dense pear orchards, supporting the customized upgrading of agricultural spraying equipment. © 2026 Society of Chemical Industry.