What environmental factors influence drift during aerial or ULV applications and what steps help reduce drift?

• A. Wind speed/direction, temperature inversions, droplet size; reduce drift by selecting appropriate nozzle and droplet size, calibrating equipment, applying under suitable wind conditions, and using buffer zones.
• B. Soil type and nutrient content
• C. Humidity alone
• D. Sun angle

Answer: (A)

Drift during aerial or ULV applications comes down to how air moves and how droplets behave in that air. Wind speed and direction determine the path droplets take after release—steady, predictable winds push droplets along a longer distance, while shifting winds can spread them off target. Temperature inversions create a stable air layer near the ground that hinders vertical mixing, so droplets don’t rise and disperse as they normally would, increasing the chance they travel farther than intended before settling. Droplet size is a core factor: smaller droplets are carried more easily by air currents and stay suspended longer, leading to more drift; larger droplets fall out of the air more quickly and are less prone to traveling off target. To reduce drift, you want to control these elements with practical steps. Selecting an appropriate nozzle and droplet size ensures you produce droplets that cover the target effectively without producing excess fine droplets that drift. Calibrating equipment guarantees the system delivers the intended droplet size and distribution rather than deviating from it. Applying under suitable wind conditions means choosing times with air movement that minimizes off-target transport while still achieving coverage, and avoiding conditions like inversions. Implementing buffer zones provides a physical margin to protect nearby non-target areas.