Describe the difference between residual and non-residual.

• A. Non-residual pesticides have no lasting effect; residual pesticides remain in soil to continue to control pests.
• B. Residual pesticides have no lasting effect; non-residual pesticides persist in soil.
• C. Residual pesticides become inactive quickly; non-residual pesticides persist in soil.
• D. Residual pesticides are only used indoors; non-residual outdoors.

Answer: (B)

The main idea is how long a pesticide continues to work after it’s applied. Residual pesticides are the ones that stay active in the environment—think soil, surfaces, or plant surfaces—for some time after application and keep providing pest control beyond that moment. Non-residual pesticides, on the other hand, break down quickly and don’t leave a lasting residue to continue fighting pests later.

This difference depends on factors like the chemical’s stability, how strongly it binds to soil particles, and environmental conditions such as sunlight, temperature, moisture, and microbial activity. Because of these factors, residual products can offer extended protection, but they also raise considerations about environmental impact and safe reentry after application. Non-residual products act fast but need to be reapplied if pests return, since they don’t linger.

So the description that best captures the distinction is that residual pesticides persist in the environment to continue control, while non-residual pesticides do not linger. Descriptions claiming residuals have no lasting effect or that non-residual persist in soil don’t fit the true meanings.