The Wind Drift of Herbicides

Herbicides

• Herbicides can be broken up into four main categories: selective or non-selective and pre-emergent or post-emergent. Selective herbicides kill a particular plant without harming others, whereas non-selective herbicides kill anything they contact. Pre-emergent herbicides kill plants before they germinate, whereas post-emergent herbicides kill plants after they have emerged.

Wind Drift

• Drift refers to the movement of an herbicide through the air. Wind drift, also called droplet or particle drift, occurs when spray droplets or dust particles are carried by air movement. Vapor drift occurs when, after application, an herbicide evaporates and the fumes are carried on wind currents. Drift may harm sensitive crops, gardens, lawns, livestock, wildlife and people. Furthermore, drift may lead to the contamination of buildings and bodies of water. Herbicides containing highly active chemicals, such as growth regulator herbicides, present the greatest likelihood of damage through drift.

Prevention

• Wind drift can be minimized by applying herbicides when the wind speed is less than 5 miles per hour. Additionally, use a sprayer with a nozzle specifically designed for drift reduction, use low spray-delivery pressures (such as 15-30 lbs. per square inch), use sprayers with smaller boom heights (the distance between the nozzle and the target), increase the droplet size of the herbicide and leave border areas unsprayed.