When does off-target pesticide drift typically occur?

Off-target pesticide drift typically occurs at the time of pesticide application or soon thereafter due to several key factors. During application, the physical forces at play, such as wind speed and direction, can carry pesticide droplets or vapors away from the intended target area. Agitation created by the application process can also generate small particles that are more susceptible to being affected by environmental conditions like wind.

Moreover, the immediate aftermath of an application is a critical window for drift to happen as it takes time for the applied chemicals to settle or adhere to the intended surfaces. Proper monitoring of environmental conditions at the time of application, including wind speed and temperature, is essential to minimize the risk of drift.

In contrast, the other options relate to different stages and processes associated with pesticides, such as storage, equipment calibration, and post-application phenomena like rainfall, which do not directly pertain to the mechanism of drift during the application process.