Which term describes a chemical applied to control weeds after they have emerged from the soil?

• A. Postemergence herbicide
• B. Preemergence herbicide
• C. Selective herbicide
• D. Nonselective herbicide

Answer: (A)

Postemergence describes applying the chemical after weeds have emerged and are actively growing, which matches the scenario in the question. Preemergence is applied before germination to prevent emergence, so it’s the opposite timing. The terms selective and nonselective refer to the range of plants affected, not when the herbicide is applied: selective targets specific weeds with less crop injury, while nonselective kills a broad range of plants. So the description that fits weeds after they’ve emerged is postemergence herbicide.