ABSTRACT

Precise placement of pesticide droplets in relation to difficult-to-reach insects such as aphids and sweet potato whitefly is increasingly critical for economic pest control. This study evaluated the effectiveness of air-assisted electrostatic, air-assisted non-electrostatic, and hydraulic spraying methods for penetrating sprays into cotton canopies and depositing droplets onto inner plant regions and leaf undersides. To assess canopy penetration, the vertical profile of spray deposition along the central axis of plants was investigated for the three application methods; results showed that air-assisted charged spray increased deposition by 1.5- to 3-fold onto vertical surfaces located from canopy top to bottom in comparison with air-assisted uncharged and hydraulic sprays. In addition, air-assisted charged spray increased deposition onto leaf undersides by 1.9- and 2.5-fold over the air-assisted uncharged spray and hydraulic spray methods, respectively. Using nozzle-drop extensions, air- assisted charged spray achieved increases in underleaf deposition of 2.3- fold over air-assisted uncharged spray and 3.6-fold over hydraulic spray.