Virginia Commercial Pesticide Applicators CORE Exam

What characterizes residual pesticides?

1. They break down quickly into nontoxic by-products

2. They remain effective for extended periods

3. They are only effective against insects

4. They require high application rates

The correct answer is: They remain effective for extended periods

Residual pesticides are characterized by their ability to remain effective for extended periods after application. This longevity allows them to continue controlling pests long after they've been applied, which is advantageous for managing pest populations over time. The extended efficacy is often due to their formulation and the way they interact with surfaces where they are applied; they may adhere to plants, soil, or structures, releasing the active ingredients gradually to maintain their effectiveness. The other options do not accurately describe residual pesticides. For instance, residual pesticides do not necessarily break down quickly into nontoxic by-products. In fact, many residual pesticides are designed to resist degradation to maximize their effectiveness over time. Additionally, residual pesticides are not limited to targeting only insects; they can also be effective against a variety of pests, including weeds and diseases. Finally, while residual pesticides can be effective at lower application rates, they do not inherently require high rates to be effective; their lasting effects are what primarily define them.