QAL Laws & Regulation Practice Exam

What is the primary cause of pesticide runoff?

1. Pesticides applied in dry conditions

2. Pesticides applied before a heavy rain

3. Using old pesticide stock

4. Overwatering the treated area

The correct answer is: Pesticides applied before a heavy rain

The primary cause of pesticide runoff is indeed related to the timing of pesticide application in relation to rainfall. When pesticides are applied before heavy rain, the soil may not have enough time to absorb the chemicals. As a result, the rain can wash these pesticides off the treated area and into nearby waterways, contributing to contamination issues. This situation is particularly problematic because runoff can carry harmful chemicals into ecosystems, affecting both aquatic life and drinking water supplies. The other options do not directly lead to runoff in the same significant way as applying pesticides just before rain. While applying pesticides in dry conditions may result in different efficacy issues, it does not inherently cause runoff. Using old pesticide stock can impact the effectiveness of pest control but is not a direct contributor to runoff events. Overwatering the treated area can lead to pesticide leaching, which is somewhat related but typically does not involve the immediate and significant volume of water that heavy rain brings. Therefore, the timing of spraying before a heavy rain is crucial to understanding runoff dynamics.