What herbicide kills only the green portion of the plant where it lands?

• A. Systemic
• B. Contact
• C. Postemergent
• D. Preemergent

Answer: (B)

The basic idea is how the herbicide moves in the plant. A contact herbicide acts only on the tissue it directly touches, so it kills just the green, sprayed portion where it lands and doesn’t move to other parts of the plant. That’s why you see dead spots or leaves where the chemical contacted, while the rest of the plant may stay alive if not touched. Systemic herbicides, by contrast, are absorbed and transported throughout the plant, often killing the entire plant rather than just the sprayed area. Timing terms like preemergent and postemergent describe when the herbicide is applied, not how it moves in the plant, so they don’t define this local-tissue effect.