Which statement about contact herbicides is true regarding perennial weeds?

Which statement about contact herbicides is true regarding perennial weeds?

• A. They are less effective on perennial weeds
• B. They are highly effective on perennials
• C. They are ineffective on annual weeds
• D. They are always selective for perennials only

Answer: (A)

Contact herbicides kill only the plant tissue they physically touch and do not move inside the plant. Perennial weeds have underground storage organs—like deep roots or rhizomes—that can survive and regrow after the foliage is damaged. Because these storage parts aren’t reached by the herbicide, regrowth is common, making these herbicides less effective on perennials than on annuals. They’re typically not reliable for long-term perennial control and may require multiple applications or pairing with other control methods. They’re not selective for perennials only, and they can affect other plants if not used carefully. This is why the true statement is that contact herbicides are less effective on perennial weeds.

Contact herbicides kill only the plant tissue they physically touch and do not move inside the plant. Perennial weeds have underground storage organs—like deep roots or rhizomes—that can survive and regrow after the foliage is damaged. Because these storage parts aren’t reached by the herbicide, regrowth is common, making these herbicides less effective on perennials than on annuals. They’re typically not reliable for long-term perennial control and may require multiple applications or pairing with other control methods. They’re not selective for perennials only, and they can affect other plants if not used carefully. This is why the true statement is that contact herbicides are less effective on perennial weeds.