What is the difference between a "contact" pesticide and a "systemic" pesticide in terms of application strategy?

• A. Contact pesticides are systemic and require soil uptake
• B. Contact pesticides move inside plant tissues to reach pests
• C. Contact kills pests on contact and generally requires thorough coverage; Systemic moves within the plant and may require soil or trunk delivery
• D. Systemic pesticides only work on exterior pests

Answer: (C)

The main idea is how the pesticide reaches pests: whether it stays on the surface to act on contact, or it is absorbed by the plant and moves to where pests feed inside the plant. A contact pesticide works only where it touches pests on exterior surfaces, so the key to effectiveness is thorough coverage of all plant surfaces where pests may contact it. A systemic pesticide, on the other hand, is taken up by the plant and translocated to other tissues, so pests feeding inside the plant or on new growth can be affected even if the spray doesn’t coat every surface. That’s why the best description says that contact pesticides kill pests on contact and require thorough coverage, while systemic pesticides move within the plant and may require soil or trunk delivery to ensure uptake. The other statements mix up where the product acts or how it’s delivered, so they don’t fit the true differences.