Virginia Commercial Pesticide Applicators CORE Exam

Which humidity level can exacerbate pesticide drift?

1. High humidity

2. Low humidity

3. Moderate humidity

4. Variable humidity

The correct answer is: Low humidity

Low humidity levels can exacerbate pesticide drift due to the increased evaporation rate of the pesticide. When humidity is low, the air is drier, which can lead to a quicker transition of liquid pesticide into vapor. This vaporization can enhance the potential for drift, as the pesticide particles may be carried further by wind currents before they have a chance to settle on the intended target area. In contrast, high humidity levels tend to slow down the evaporation process, allowing droplets to remain larger and settle more quickly, reducing the likelihood of drift. Moderate humidity does not pose as significant a risk, as the conditions are more stable for pesticide application. Variable humidity can also lead to unpredictable conditions that may not uniformly favor drift or deposition, but low humidity is distinctly known to create conditions that can increase drift risk due to the rapid evaporation of pesticide products.