Which characteristic describes systemic (systematic) herbicides?

Which characteristic describes systemic (systematic) herbicides?

• A. Applied to plant foliage and then moves throughout the plant, killing over days or weeks
• B. Applied to soil to prevent germination
• C. Act rapidly within hours and are nonselective
• D. Are only effective on annual weeds

Answer: (A)

Systemic herbicides are defined by their uptake and movement inside the plant. After the chemical is absorbed—often through foliage—it is translocated via the plant’s vascular system to other tissues, including growing points and roots. Because the toxin travels within the plant, the entire plant eventually dies, but visible effects and death occur over days to weeks rather than hours. This internal spread is what makes systemic herbicides effective for whole-plant control, including perennials, not just the parts that were directly treated. So, applying to foliage and then having the chemical move through the plant to kill it over time describes a systemic herbicide. In contrast, soil-applied products that prevent germination act at the soil level, rapid contact-only products kill tissues at the point of contact, and systemic products are not limited to annual weeds.

Systemic herbicides are defined by their uptake and movement inside the plant. After the chemical is absorbed—often through foliage—it is translocated via the plant’s vascular system to other tissues, including growing points and roots. Because the toxin travels within the plant, the entire plant eventually dies, but visible effects and death occur over days to weeks rather than hours. This internal spread is what makes systemic herbicides effective for whole-plant control, including perennials, not just the parts that were directly treated.

So, applying to foliage and then having the chemical move through the plant to kill it over time describes a systemic herbicide. In contrast, soil-applied products that prevent germination act at the soil level, rapid contact-only products kill tissues at the point of contact, and systemic products are not limited to annual weeds.