Which factor is likely to decrease the effectiveness of a pesticide application?

Excessive wind speed is a significant factor that can compromise the effectiveness of pesticide applications. When wind speeds are high, the spray droplets can be carried away from the target area, resulting in uneven application and reduced coverage of the pests or plants intended for treatment. This can lead to poor pest control due to insufficient contact with the pesticide, potentially allowing pests to survive or not be adequately managed. Additionally, high winds may lead to drift, where the pesticide moves to non-target areas and can cause unintended harm to beneficial insects, plants, or nearby environments.

In contrast, low ambient temperatures can slow the action of pesticides but do not inherently diminish their effectiveness. High humidity generally aids in maintaining the stability of pesticides and can enhance their effectiveness by aiding adhesion and absorption. Lastly, using high concentrations may increase the effectiveness of the pesticide if it is within the manufacturer's recommended limits, as more active ingredient presence can lead to better pest control. However, exceeding those limits can lead to phytotoxicity or other issues.