Paraquat is a non-selective, contact herbicide that rapidly destroys plant tissues. It works by disrupting photosynthesis, leading to the formation of toxic reactive oxygen species (ROS) that damage cell membranes and kill plant cells.
How Does Paraquat Work?
1. Disrupts Photosynthesis
- Paraquat interferes with electron transport in chloroplasts.
- This leads to the production of superoxide radicals, which are highly reactive molecules that damage cell structures.
2. Causes Rapid Cell Membrane Destruction
- The oxidative stress created by paraquat destroys plant cell membranes.
- This results in water loss, desiccation, and tissue collapse, causing rapid wilting and death.
3. Fast-Acting & Irreversible Damage
- Symptoms appear within hours of application.
- Leaves dry out and turn brown, usually within 24 to 48 hours.
- The damage is permanent, and the plant cannot recover.
Why is Paraquat So Effective?
Works on almost all green plants (non-selective).
Rapid burn-down effect, making it ideal for quick weed control.
No systemic action – does not translocate to roots, so it kills only the treated areas.
How is Paraquat Applied?
1. Foliar Spray (Most Common Method)
- Applied directly to leaves using sprayers.
- Best results occur when applied to actively growing weeds.
- Works well in warm, sunny conditions when photosynthesis is active.
2. Directed Spray (Row Crops & Orchards)
- Applied in orchards, vineyards, or between row crops to control weeds without harming the main crop.
- Must be carefully directed to avoid contact with desirable plants.
3. Pre-Plant or Pre-Emergence Application
- Often used to clear fields before planting crops.
- Controls existing vegetation without affecting seeds or crops that have not yet emerged.
4. Spot Treatment
- Used for targeted weed control in non-crop areas, fence lines, and roadsides.
- Applied with hand-held or backpack sprayers.
5. No-Till & Conservation Tillage Systems
- Frequently used in no-till farming to kill weeds without disturbing the soil.
- Helps preserve soil structure while preventing weed competition.
Paraquat remains one of the fastest and most effective herbicides, but due to its high toxicity, strict handling precautions and application regulations must be followed.