When do pesticides become problematic?

Pesticides become problematic primarily when they move off target, meaning they affect areas or organisms that were not intended to be treated. This can happen due to factors like drift during application, runoff from rain, or improper application methods. When pesticides are applied incorrectly or at the wrong times, they can impact non-target species, including beneficial insects, wildlife, and even humans, as well as contaminate soil and water sources.

In contrast, the other options reflect scenarios where the use and handling of pesticides are done correctly, promoting safety and efficacy. For instance, when pesticides are used correctly, they should ideally be effective against the intended pest without causing unintended harm. Proper storage ensures that pesticides remain effective and do not pose hazards due to degradation or spillage. Likewise, labeling is essential for safe handling and provides guidance on the appropriate use of the pesticide, ensuring that users maintain safety protocols and comply with regulations.