What is spray drift, and which factors influence drift during outdoor pesticide applications?

• A. Drift is the off-target movement of spray droplets; factors include wind speed and droplet size only.
• B. Drift is the off-target movement of spray droplets; factors include droplet size, nozzle type, spray pressure, boom height, wind speed/direction, and temperature.
• C. Drift refers to the pesticide residues on the tank; factors include tank cleanliness and pH.
• D. Drift is pesticide degradation in sunlight; factors include UV exposure and humidity.

Answer: (D)

Spray drift is the off-target movement of spray droplets after an outdoor application, meaning droplets can travel beyond the intended target and reach other crops, water, or people. Several factors influence how far and where that drift occurs. Droplet size matters: smaller droplets are more easily carried by wind and stay airborne longer than larger droplets. The nozzle type and the spray pressure shape the droplets and their velocity, so they can travel differently under the same conditions. Boom height affects how far droplets can move before they reach the target; higher booms can increase drift potential. Weather conditions matter too—wind speed and direction obviously push droplets off target, and temperature (along with air stability) influences evaporation and air currents, which can enhance drift risk. The combination of all these factors gives the most accurate picture of drift potential.

Other options describe residues in the tank or pesticide degradation in sunlight, which are not drift.