RE Mickle, REMSpC Spray Consulting
G. Rousseau, SOPFIM

SERG Project #1999/04-02


Executive Summary

All treatment (ground or air) programs result in the potential for off-target movement of pesticides that may pose an environmental risk. While ground applicators can modify equipment to reduce drift, aerial applicators have fewer options available for drift minimization. In aerial agricultural programs, vortex modifiers (winglets) have shown promise in enhancing deposit uniformity and reducing off-target drift. However, in forestry insecticide programs, wing-tip vortices can promote deposit closer to the spray line due to a more rapid movement of small drops into the canopy.

A series of trials were completed to compare deposit from two Cessna AgTrucks, one fitted with Ag-Tips and the other having conventional winglets. Each aircraft used four Micronair AU4000s producing a drop size distribution around 80µm. Both aircraft were flown at 15m agl. Sprays were completed in crosswinds ranging from 7-12kph. Deposit sampling at 5m intervals using Kromekote™ cards and petrie dishes provided drop density, drop size and volume (BIU/ha) measurements to 300m downwind of the flight line. In two of the three trials, peak deposit from the conventional AgTruck was closer to the flight line. The C188 with Ag-Tips had a somwhat broader swath resulting in enhanced deposit out to 150m from the flight line with reduced deposit beyond and potentially reduced drift in the far-field. A broader swath with enhanced drop density could potentially result in improved efficacy.