Comparative spray drift studies of aerial and ground applications 1983–1985

The amount of off-site pesticide spray drift from aerial and ground applications was determined at 26 sites across Ontario. These were conducted along transects, parallel and at right angles to the flight path during aerial spray applications and at right angles to the direction of ground spray applications. All sites monitored were where commercial spray operations were in progress. The aerial applications involved both fixed wing aircraft and helicopters and the ground applications involved concentrated air-blast machines and high and low pressure boom sprayers. Deposits of spray drift outside the target area were common to all spray equipment monitored. All except low-pressure boom spraying equipment resulted in measurable spray drift to 80 m off-target with appreciable deposits up to 30–40 m. In a forest spray operation, where insecticide release was the highest, measurable residues were found up to 120 m off-target. The amount of chemical deposited off-target varied with the chemical, the climatical conditions and the equipment used. With a low-pressure boom sprayer, serious drift was confined to 9 m off-target and measurable residues to 15 m.