Oregon Pesticide Practice Test

Which two factors are most important in avoiding vapor drift?

1. Humidity and pesticide concentration

2. Temperature and pesticide volatility

3. Wind speed and distance from application site

4. Soil type and rainfall levels

The correct answer is: Temperature and pesticide volatility

Focusing on temperature and pesticide volatility is crucial in avoiding vapor drift because these two elements directly impact how pesticides behave once they are applied. Temperature plays a significant role in the rate at which pesticides volatilize, meaning how quickly they can change from a liquid to a gas. High temperatures can increase volatility, leading to more vapors that can drift away from the intended application area. Pesticide volatility is a property of the chemical formulation itself; some pesticides are designed to evaporate more readily than others. Therefore, understanding both the temperature conditions at the time of application and the inherent volatility of the substances being used allows applicators to make informed decisions about when and how to apply pesticides to minimize the risk of drift. While wind speed and distance from the application site also contribute to drift potential, their effects are secondary to temperature and volatility, as high winds can carry vapors further but are influenced by how much vapor is produced in the first place. Humidity and pesticide concentration can affect overall efficacy but are less directly related to the phenomenon of volatilization and resultant drift. Soil type and rainfall levels pertain more to soil management and runoff rather than airborne drift following application.