What does a "vapor drift" indicate about a pesticide?

A "vapor drift" occurs when pesticide vapors are released into the air, indicating that the pesticide is volatile. Volatility refers to the tendency of a substance to evaporate and exist as a gas at relatively low temperatures. Pesticides with high volatility have the potential to travel away from the target application area through the air, leading to potential off-target exposure to sensitive areas or unintended crops.

Understanding vapor drift is crucial for applicators as it helps in making informed decisions about when and how to apply certain pesticides, ensuring they remain within the designated treatment area and minimize the risk of contamination to neighboring plants, ecosystems, and humans. Moreover, recognizing the volatile nature of a pesticide can guide safety protocols, application methods, and timing to reduce drift.

The other options pertain to different characteristics of pesticides: persistence in soil refers to how long a pesticide remains in the soil without breaking down, opacity describes the visibility of a mixture, and resistance to leaching relates to a pesticide's tendency to wash away with water. These factors are important in their own contexts but do not pertain to the definition of "vapor drift."