Question

Which one is a non-selective contact herbicide?

• A. Paraquat
• B. Glyphosate
• C. Metribuzin
• D. Isoproturon

Hint:

Always distinguish: Paraquat = non-selective contact, Glyphosate = non-selective systemic.

Answer 1

The Correct Option is A

Step 1: Types of herbicides.
Herbicides can be classified as:
- Selective herbicides: Kill specific weeds without harming the crop.
- Non-selective herbicides: Kill all types of plants they come into contact with.
Additionally, they may act as contact (killing only the part they touch) or systemic (moving through the plant system).
Step 2: About Paraquat.
Paraquat is a non-selective, contact herbicide.
It kills green plant tissue immediately upon contact by destroying cell membranes.
It does not move systemically in the plant, so underground parts may survive if not sprayed.
It is widely used for weed control in non-crop areas and as a desiccant before harvest.
Step 3: Analysis of options.
- (A) Paraquat: Correct, non-selective contact herbicide.
- (B) Glyphosate: Non-selective, but systemic, not contact.
- (C) Metribuzin: Selective, systemic herbicide, not purely contact.
- (D) Isoproturon: Selective herbicide, used for broadleaf weeds in wheat.
Step 4: Conclusion.
Thus, Paraquat is the correct non-selective contact herbicide.