Question

Glyphosate is used for weed control as a \(\underline{\hspace{3cm}}\).

• A. Post-emergence selective herbicide
• B. Post-emergence non-selective herbicide
• C. Pre-emergence selective herbicide
• D. Pre-emergence non-selective herbicide

Hint:

Remember: Glyphosate is systemic, post-emergence, and non-selective. It is used in zero-tillage farming, plantation crops, and to clear weeds before sowing.

Answer 1

The Correct Option is B

Step 1: Understand glyphosate.
Glyphosate is a widely used systemic herbicide. It inhibits the enzyme EPSP synthase (5-enolpyruvylshikimate-3-phosphate synthase), blocking the shikimic acid pathway essential for amino acid synthesis in plants.

Step 2: Classify it by stage and selectivity.
- Stage: Glyphosate is applied after the emergence of weeds, i.e., it is a post-emergence herbicide.
- Selectivity: Glyphosate kills a wide range of plants (grasses, broadleaf weeds, shrubs, even trees), meaning it is non-selective.

Step 3: Eliminate incorrect options.
- (1) Post-emergence selective herbicide → Wrong, it is not selective.
- (2) Post-emergence non-selective herbicide → Correct.
- (3) Pre-emergence selective herbicide → Wrong, glyphosate is not pre-emergence.
- (4) Pre-emergence non-selective herbicide → Wrong, it is not pre-emergence.

Step 4: Conclusion.
Hence, glyphosate is a post-emergence non-selective herbicide.

Final Answer: \[ \boxed{\text{Glyphosate is a post-emergence non-selective herbicide.}} \]