Herbicide Formulations

1. Wettable Powders (WP)

• Definition: Finely ground powders with low solubility in water. They are mixed with water before spraying, forming a suspension.
• Features: Require constant agitation during spraying to avoid settling.
• Advantages: Easy to store, less risk of phytotoxicity.
• Disadvantages: Dusty, inhalation hazard, needs good mixing.
• Examples: Simazine, 2,4-D sodium salt, Diuron, Linuron. Atrazine WP (used in maize and sorghum).

2. Water-Soluble Concentrates (WSC or SL)

• Definition: Herbicides that dissolve completely in water, forming a true solution.
• Features: Easy to measure and apply, no sedimentation.
• Advantages: No agitation needed, easy handling.
• Disadvantages: Corrosive to equipment, may cause phytotoxicity if overdosed.
• Examples: 2,4-D amine, Dicamba, Diquat, Paraquat.

3. Emulsifiable Concentrates (EC)

• Definition: Active ingredient dissolved in oil/organic solvent with an emulsifier. When mixed with water, forms a stable emulsion.
• Features: Popular in agriculture due to uniform spreading and penetration.
• Advantages: Easy mixing, high effectiveness, good foliar coverage.
• Disadvantages: Flammable, phytotoxic risk at high doses.
• Examples: 2,4-D ester, Alachlor, Nitrofen, Diallate. Butachlor EC (used in rice).

4. Liquid Suspensions (LS or SC = Suspension Concentrates)

• Definition: Active ingredient finely ground and suspended in a liquid (often oil-based). When diluted with water, forms a stable suspension.
• Features: Better stability than WP, safer than EC.
• Examples: Atrazine, Cyprazine, Nitralin.

5. Soluble Powders (SP)

• Definition: Powder formulations that dissolve completely in water, making a clear solution.
• Features: No agitation required after dissolving.
• Advantages: Easy to handle and apply.
• Disadvantages: Limited to herbicides with high water solubility.
• Examples: Sodium salt of 2,4-D, Trichloroacetic acid (TCA), Dalapon, Endothall.

6. Granules (G)

• Definition: Inert clay/mineral granules coated with herbicide solution, dried, and applied directly to soil.
• Features: Applied with spreaders; do not need mixing with water.
• Advantages: Safe to handle, less drift, controlled release, useful for soil incorporation.
• Disadvantages: Less effective on foliar weeds, bulky, costly transport.
• Examples: Butachlor granules, 2,4-D granules.

Comparison Table of Herbicide Formulations