When is vapor drift more likely to occur?

Vapor drift is more likely to occur at higher temperatures, specifically above 85 degrees Fahrenheit. At elevated temperatures, the volatility of certain pesticides increases, causing them to turn into a gas more readily. This gas can move away from the intended application site, carried by wind or air currents. Higher temperatures enhance the rate of evaporation, which can contribute to the potential for vapor drift to occur, resulting in the unintended movement of pesticides to non-target areas.

In contrast, cooler temperatures, foggy conditions, and high humidity tend to reduce the likelihood of vapor drift. Cooler temperatures slow down the evaporation rate, while foggy days can create moisture in the air that further inhibits the volatility of pesticides. High humidity levels also contribute to a decrease in evaporation rates, helping to keep pesticides closer to their application sites. Thus, the conditions under which vapor drift is most likely to occur clearly correlate with increased ambient temperatures.