Which statement best contrasts systemic and contact herbicides?

Which statement best contrasts systemic and contact herbicides?

• A. Systemic works only on surface tissue; contact moves inside
• B. Systemic moves within the plant; contact kills only treated tissue
• C. They are the same
• D. Systemic are not used for perennials

Answer: (B)

The main idea is how the herbicide moves inside the plant. Systemic herbicides are absorbed and then transported through the plant’s vascular system, so they can reach new growth and even underground parts to kill the whole plant. Contact herbicides, on the other hand, act only on the tissue they touch and do not move inside the plant, so their effect is limited to the treated surface. Because of that, the statement that systemic moves within the plant and contact kills only treated tissue best contrasts the two.

The main idea is how the herbicide moves inside the plant. Systemic herbicides are absorbed and then transported through the plant’s vascular system, so they can reach new growth and even underground parts to kill the whole plant. Contact herbicides, on the other hand, act only on the tissue they touch and do not move inside the plant, so their effect is limited to the treated surface. Because of that, the statement that systemic moves within the plant and contact kills only treated tissue best contrasts the two.