Under what condition are spray drift issues likely to occur?

Spray drift issues are most likely to occur during a temperature inversion. This phenomenon happens when a layer of warm air traps cooler air near the ground, preventing proper mixing of the atmosphere. As a result, any airborne particles, including pesticide droplets, can remain suspended and drift away from the intended application area rather than dissipating or falling to the ground as they would under normal atmospheric conditions. This can lead to unintended pesticide exposure to non-target areas, including sensitive habitats or residential areas, thus increasing the risk of environmental and health impacts.

In contrast, high humidity conditions typically help droplets fall more quickly to the ground due to increased weight and can reduce the distance they travel. Low air pressure can also influence drift but is less of a direct factor than a temperature inversion. Calm winds would generally result in minimal drift, as there would be insufficient airflow to carry the particles away from the targeted area. Understanding these atmospheric conditions is crucial for effective pest management strategies and minimizing unintended consequences of pesticide application.