Which type of herbicides kills only the plants or plant tissues it touches during application?

• A. Growth Regulators
• B. Systemic herbicides
• C. Contact herbicides
• D. Pre-emergents

Answer: (C)

Killing only the tissues touched during application comes from a herbicide that acts locally and does not move through the plant. This local action is what defines a contact herbicide: it damages or kills the plant parts it actually contacts, and there’s little to no translocation to other tissues. Because of that, you must cover the weed thoroughly so all the targeted tissue is hit; otherwise, untreated areas will survive.

Growth regulators disrupt growth processes and are typically absorbed and translocated within the plant, reaching sites beyond the initial contact. Systemic herbicides rely on movement through the plant’s vascular system to affect distant tissues. Pre-emergents stay in the soil to prevent germination and don’t act on existing plant tissue. Therefore, the option that describes killing only what you touch is contact herbicides.