Which type of herbicide is more effective on larger, bushier weeds than on small weeds that have just sprouted?

• A. Systemic
• B. Contact
• C. Non-Selective
• D. Residual

Answer: (A)

Systemic herbicides are taken up by the plant and moved through its vascular system to reach all parts, including roots and new growth. Because they travel inside, they can affect larger, bushier weeds where there’s more tissue to absorb the chemical and where killing the entire plant (not just the surface) is needed. This translocation lets the herbicide reach underground or far-growing parts that a bigger weed relies on. In contrast, a contact herbicide works only on the tissue it touches and doesn’t move inside the plant, so it’s less reliable for larger plants. Non-selective describes the range of species affected, not how the chemical moves within the plant, and residual describes how long the chemical remains in the soil or surfaces, not its movement or effectiveness on bigger weeds. So, the option describing movement through the plant to control larger, bushier weeds is systemic.