Which environmental factor is not listed as influencing spray drift?

• A. Soil type
• B. UV intensity
• C. Wind speed and direction
• D. Relative humidity

Answer: (A)

Spray drift is controlled by how droplets move through the air before they reach a target, which depends on atmospheric conditions and the spray’s characteristics. Wind speed and direction directly push and carry droplets away from the target, so they strongly influence how far drift can occur. Relative humidity affects evaporation of droplets in flight; lower humidity tends to cause more evaporation, creating smaller droplets that can travel farther. UV intensity mostly affects what happens after the droplet lands, such as degradation of the pesticide by sunlight, rather than how droplets move in the air during application. Soil type, however, influences what happens after deposition—how quickly the chemical infiltrates soil, binds to particles, or runs off—rather than the airborne travel of the spray. Therefore, soil type is not listed as influencing spray drift. To minimize drift, consider factors like choosing appropriate wind conditions, adjusting nozzle types and droplet sizes, and maintaining proper application height.