Herbicide Drift Potential All herbicides are subject to particle drift. Vapor drift potential varies by each herbicides vapor potential. Droplet size controls both types of drift. Wind, temperature and humidity affects drift severity.
Herbicides with High Drift Damage Potential High vapor potential herbicides. Herbicides that are active at very low application rates. Herbicides that are Plant Growth Regulators (PGRs)
Note: Spray particles under 50 microns in diameter may remain suspended in the air indefinitely or until they evaporate.
In relatively dry, warm air (e.g., 30 percent relative humidity and 78F), a 100-micron droplet quickly loses water by evaporation and becomes less than half its original diameter (one-eighth of its original volume) while falling only 2.5 feet. By comparison, in relatively moist air (e.g., 70 percent relative humidity and 78F), a 100-micron particle will fall 5 feet and hit the ground before evaporating to half its original diameter. Small droplets become smaller very quickly
Spray Drift Affects Sensitive Crops R. David Myers Extension Educator firstname.lastname@example.org Any Questions?