What is the difference between contact and translocated herbicides?

What is the difference between contact and translocated herbicides?

• A. Contact: kill treated tissue only; Translocated: move throughout plant.
• B. Contact: kill the whole plant; Translocated: stay in the sprayed area.
• C. Contact: move throughout plant; Translocated: kill treated tissue only.
• D. Contact: kill roots only; Translocated: kill leaves only.

Answer: (A)

Herbicide behavior hinges on whether the chemical stays where it’s applied or moves inside the plant. Contact herbicides kill only the plant tissue they touch and don’t travel to other parts, so their effect is limited to the sprayed area. Translocated (systemic) herbicides are taken up and moved through the plant’s vascular system, allowing the chemical to reach and kill tissues beyond the point of contact, often affecting the entire plant. That’s why the statement describing contact as killing treated tissue only and translocated as moving throughout the plant best captures the difference. In practice, this means you need thorough coverage for contact herbicides, while systemic ones can affect parts you didn’t spray as the chemical moves to growing points and roots. Examples: paraquat is a contact herbicide; glyphosate is systemic.

Herbicide behavior hinges on whether the chemical stays where it’s applied or moves inside the plant. Contact herbicides kill only the plant tissue they touch and don’t travel to other parts, so their effect is limited to the sprayed area. Translocated (systemic) herbicides are taken up and moved through the plant’s vascular system, allowing the chemical to reach and kill tissues beyond the point of contact, often affecting the entire plant. That’s why the statement describing contact as killing treated tissue only and translocated as moving throughout the plant best captures the difference. In practice, this means you need thorough coverage for contact herbicides, while systemic ones can affect parts you didn’t spray as the chemical moves to growing points and roots. Examples: paraquat is a contact herbicide; glyphosate is systemic.