Which of the following can be a negative consequence of pesticide overspray?

Pesticide overspray can lead to contamination of non-target areas, which is a significant negative consequence of its application. This occurs when pesticides intended for a specific target organism inadvertently drift or are applied to areas not meant to receive the treatment, such as nearby ecosystems, water bodies, or other plants. This unintended exposure can harm beneficial organisms, disrupt local ecosystems, and lead to the accumulation of harmful substances in the environment.

In contrast, immediate pest control is a desired outcome of pesticide application, and benefits to adjacent crops may occur if the overspray inadvertently reduces pest populations that can harm those crops. Increased soil fertility is generally unrelated to pesticide application, as most pesticides do not contribute to enhancing soil nutrient levels. Thus, contamination of non-target areas is clearly the most harmful consequence among the options provided.