MDARD Michigan Core Pesticide Applicator Practice Exam

Which factor is most critical in preventing vapor drift when applying pesticides?

1. Humidity and temperature

2. Droplet size and wind speed

3. Time of application

4. Type of pesticide used

The correct answer is: Droplet size and wind speed

The factor that is most critical in preventing vapor drift when applying pesticides is droplet size and wind speed. When pesticides are applied, the size of the droplets that are released into the air plays a significant role in their trajectory and ability to remain suspended. Larger droplets are less likely to drift away from the target area because they are affected more by gravity and less by wind. Conversely, smaller droplets can remain airborne for longer periods and are more prone to being carried off-site by wind conditions. Wind speed is another crucial element. High wind speeds can increase the likelihood of drift by moving pesticide droplets away from the target area before they have a chance to settle on the intended surface. Therefore, both droplet size and wind speed directly impact the potential for vapor drift during the application process. Applying pesticides when conditions are suitable—characterized by appropriate droplet size and minimal wind—helps mitigate the risks associated with drift, ensuring that the pesticide remains effective and reduces the potential for unintended exposure to non-target areas.