Development and Evaluation of a Laser-Guided Air-Assisted Sprayer in Nursery Production.

An automated variable-rate, air-assisted precision sprayer was developed to increase application efficiency and minimize non-target spray losses. The intelligent spray system is able to characterize the presence, size, shape, and foliage density of target trees and assess sprayer travel speed to apply variable amounts of pesticides based on tree canopy needs in real time. It integrates a high-speed, 270° radial and 30-m range laser scanning sensor in conjunction with a non-contact Doppler radar travel speed sensor, a sophisticated automatic nozzle flow rate controller, an embedded computer, a touch screen, a manual switch box, and 40 pulse-width-modulated variable-rate nozzles on a multi-port air-assisted delivery system.

Field efficacy trials in 2013 and 2014 demonstrated that the laser-guided variable-rate sprayer had comparable insect control and comparable or lower disease infection rates than the conventional air-assisted sprayers. Comparing insecticide applications applied with the laser-guided sprayer and either a conventional tower air-assisted sprayer or conventional radial air-blast sprayer showed no significant differences in the survival rates of aphids on crabapples, potato leafhoppers on red maple, total number of pear sawflies on cherry trees, presence of rusts on 3-year old flowering pears, and lower powdery mildew infections on Norway maple trees.

Compared with the radial air-blast sprayer, the intelligent sprayer reduced chemical costs for pear rust by 59% and by 32% for pear sawfly control on cherry. Chemical costs for scab control on crabapple with the intelligent sprayer were 62% lower than those with the tower sprayer and 70% lower for powdery mildew control on Amelanchier.

The intelligent sprayer reduced the volume of pesticide applied use by 43% to 80% with comparable insect control and equal or better disease control.