MDARD Michigan Core Pesticide Applicator Practice Exam

What is the main source of surface water contamination by pesticides according to best practices?

1. Drift from aerial applications

2. Runoff and erosion

3. Vapor drift during treatment

4. Leaching into groundwater

The correct answer is: Runoff and erosion

Runoff and erosion are recognized as the primary mechanisms for surface water contamination by pesticides. When it rains or when irrigation occurs, excess water can carry pesticide residues from agricultural fields into nearby waterways. This movement involves both the physical action of water flowing over the land, which can erode soil that has absorbed pesticides, and the direct transport of dissolved pesticides that have mixed into the water. Best practices in pesticide application emphasize the importance of managing runoff, such as by employing buffer zones, cover crops, and other erosion control measures. This is crucial because reducing runoff minimizes the likelihood that pesticides will reach surface water bodies, where they can have harmful effects on aquatic ecosystems and water quality. The other options, while they may contribute to pesticide contamination in specific scenarios, do not represent the main source of surface water contamination within the broader context of agricultural pesticide use.