Which of the following describes factors that influence pesticide drift?

• A. Droplet size, nozzle type, wind speed/direction (and temperature/humidity).
• B. Label color, packaging material, and storage temperature.
• C. Crop type, soil type, and irrigation schedule.
• D. Soil moisture, pH, and microbial activity.

Answer: (C)

Pesticide drift comes down to how spray droplets behave as they travel through the air. The most important influences are the size of the droplets, the nozzle that produces the spray, and the current atmospheric conditions like wind and temperature/humidity. Smaller droplets are easily carried by air and can travel far from the target, increasing drift risk. The nozzle type shapes the spray pattern and the distribution of droplet sizes; some nozzles create finer sprays that drift more, while others produce coarser droplets that tend to land closer to the target. Wind speed and direction push droplets downwind and can stretch the landing area far beyond the intended spot. Temperature and humidity affect evaporation and drying of droplets in flight, which can change their size and drift potential as they move.

Other factors listed don’t directly control how airborne droplets move. For example, label color, packaging, and storage affect handling and safety but not the physics of drift. Crop type, soil type, and irrigation schedule relate to when and where you apply, or how the pesticide behaves after it lands, rather than how it drifts through the air.