An herbicide applied after the target weed has emerged is known as what? Provide an example used in rangeland.

• A. Pre-emergent herbicide; example atrazine.
• B. Post-emergent herbicide; example glyphosate.
• C. Systemic herbicide; example paraquat.
• D. Contact herbicide; example glyphosate.

Answer: (B)

Applying herbicide after the weed has emerged is post-emergent. This means the chemical is used on weeds that are already visible and actively growing, targeting them from the foliage down as they’re present in the stand. Glyphosate is a common example in rangeland because it is systemic; it moves within the plant and can kill the whole shoot and roots when applied to the foliage.

For contrast, a pre-emergent herbicide is applied before weed seeds germinate to prevent emergence, with atrazine often serving that soil-residue role. Some products act primarily on contact, like paraquat, which kills only the tissue it touches and doesn’t move through the plant.