Proper nozzle selection and maintenance will help ensure consistent, accurate application and optimal product performance.
Spray drift is the movement of droplets through the air, during or after application, to a site other than the intended target. Many factors influence spray drift, but university researchers say these three are most important:
- Wind speed. When wind speed doubles, it results in an almost 70 percent increase in drift 90 feet downwind from the sprayer. Spray when the wind speed is 10 mph wind or less.
- Boom height. When boom height rises from 18 inches to 36 inches, the amount of drift increases 350 percent 90 feet downwind. Consider AutoBoom™ automatic boom height control for your Patriot® series sprayer to help maintain boom height.
- Distance downwind. If the distance downwind is doubled, the amount of drift decreases five-fold. If the distance downwind goes from 100 to 200 feet, you have only 20 percent as much drift at 200 feet as at 100 feet. You might need to spray only part of a field and then finish when conditions change.
Watch for air temperature inversions
Air temperature inversions occur under what we typically would consider ideal conditions for spraying — clear and calm. But these situations also provide conditions conducive for tiny, aerosol-size droplets to drift away from their targets.4 This Extension publication from North Dakota State University provides a detailed explanation about temperature inversions, how they occur and what conditions are conducive to temperature inversions.
Pick the right nozzles and maintain them well
Spray droplet size plays an important role in drift. Generally, small droplets do not have enough mass to drop fast, so they remain airborne and exposed to air movement longer than larger droplets.