Acetochlor: A Selective Pre-Emergent Herbicide for Weed Control

Definition:
Acetochlor is a selective, pre-emergent chloroacetanilide herbicide used to control annual grasses and certain broadleaf weeds. It is widely applied in crops such as corn, soybeans, sugarcane, and peanuts. Acetochlor is valued for its residual activity and its role in integrated weed management programs.

Chemical Characteristics of Acetochlor:

• Chemical Name: 2-Chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide

• Molecular Formula: C₁₄H₂₀ClNO₂

• Molecular Weight: 269.8 g/mol

• Appearance: Clear to pale yellow liquid.

• Solubility: Low solubility in water; soluble in organic solvents.

• Stability: Stable under normal conditions but degrades under strong sunlight or alkaline conditions.

Mode of Action:

Acetochlor inhibits long-chain fatty acid synthesis in germinating weed seeds, disrupting cell division and preventing seedling growth. It is absorbed primarily through shoots of emerging weeds.

Uses and Applications:

1. Target Weeds:

   • Controls annual grasses such as foxtail, barnyard grass, crabgrass, and certain broadleaf weeds like pigweed and lambsquarters.

2. Crops:

   • Commonly used in corn, soybeans, peanuts, sugarcane, and cotton.

3. Timing:

   • Applied pre-emergence (before weed germination) or early post-emergence (before weeds reach early leaf stages).

Benefits of Acetochlor:

• Broad-Spectrum Control: Effective against key annual grass and some broadleaf weeds.

• Residual Activity: Provides extended control during early crop growth.

• Compatibility: Can be tank-mixed with other herbicides to broaden weed control spectrum.

• Crop Selectivity: Safe on labeled crops when used correctly.

Limitations:

• Limited Post-Emergence Activity: Most effective before weeds emerge.

• Soil Activation Needed: Requires rainfall or irrigation for proper activation.

• Environmental Concerns: May leach to groundwater in sandy soils with low organic matter.

Recommended Application:

• Dosage: Typically 1.0–2.5 L/ha depending on soil type, weed pressure, and crop.

• Method: Soil surface spray, followed by incorporation or rainfall.

• Precautions:

  • Avoid application near water sources.

  • Rotate with herbicides of different modes of action to prevent resistance.

  • Use protective gear during handling and application.

Storage and Handling:

• Storage: Keep in tightly sealed containers in cool, dry, ventilated areas.

• Shelf Life: Generally stable for 2–3 years under recommended conditions.

• Safety: Toxic to aquatic life; avoid contamination of water bodies.

FAQ on Acetochlor:

Q1: What is the primary use of Acetochlor?
A1: It is mainly used for pre-emergent control of annual grasses and some broadleaf weeds in crops like corn and soybeans.

Q2: Does Acetochlor control emerged weeds?
A2: No, it primarily works on germinating weeds and is less effective post-emergence.

Q3: How is Acetochlor activated in the soil?
A3: It requires rainfall or irrigation to move the herbicide into the weed germination zone.

Q4: Can Acetochlor be mixed with other herbicides?
A4: Yes, it is commonly tank-mixed with atrazine, glyphosate, or other herbicides for broader weed control.