Alachlor 43% EC Herbicide | Pre-Emergence Weed Control for Crops

Technical Specifications

• Active Ingredient: Alachlor (CAS No. 15972-60-8)
• Molecular Formula: C₁₂H₁₈ClNO₂
• Molecular Weight: 241.73 g/mol
• Mode of Action: Inhibits VLCFA synthesis, blocking cell membrane formation in germinating weeds.
• Formulation: 43% EC (430 g/L Alachlor)
• Physical State: Light amber to brown oily liquid
• Solubility: 242 ppm in water at 25°C; soluble in acetone, xylene
• Vapor Pressure: 2.9×10⁻⁷ mmHg at 25°C
• pH Range: 5.0–8.0 (stable in most agricultural waters)

Mode of Action

1. Soil Uptake: Absorbed by germinating weed roots and young shoots.
2. Biochemical Blockade: Inhibits acetyl-CoA carboxylase, preventing elongation of fatty acid chains.
3. Growth Arrest: Disrupts meristematic tissue development in coleoptiles (grasses) and hypocotyls (broadleaves).
4. Symptom Timeline:
   • 3–7 days: Stunted shoot growth, lack of new leaf emergence.
   • 10–14 days: Chlorosis and necrosis in emerging seedlings.

Application Guide

Application Tips:

• Water Volume: Use 200–400 L/ha for uniform soil coverage.
• Soil Moisture: Optimal efficacy requires 10–20 mm rainfall/irrigation within 7 days of application.
• Tank Mixes:
  • Corn: Alachlor 43% EC + atrazine (broadens spectrum to broadleaf weeds).
  • Soybeans: Alachlor 43% EC + metribuzin (enhances broadleaf control).
• Soil Type Adjustments:
  • High organic matter (OM >3%): Use higher rates (3.0–4.0 L/ha).
  • Sandy soils: Use lower rates (1.5–2.0 L/ha) to reduce leaching risk.

Key Advantages

1. Broad-Spectrum Control: Effective against 20+ annual grassy and broadleaf weeds.
2. Residual Activity: 4–6 weeks of soil protection, reducing need for post-emergence applications.
3. Crop Safety: Selective in corn, soybeans, and cotton due to metabolic detoxification.
4. Cost-Effective: Low application rates (1.5–5.0 L/ha) compared to other pre-emergence herbicides.
5. Tank Mix Flexibility: Compatible with most common herbicides (e.g., glyphosate, acetochlor) for resistance management.

Safety & Environmental Notes

• Toxicity:
  • Low acute toxicity to mammals (LD₅₀ > 2000 mg/kg for rats).
  • Highly toxic to fish and aquatic invertebrates (keep 100 m from water bodies).
• Environmental Impact:
  • Soil half-life: 7–21 days (degrades via microbial action and photolysis).
  • Moderate leaching potential in sandy soils; avoid use in areas with shallow groundwater.
• Storage: Store in cool, dry place; protect from direct sunlight and freezing.

Resistance Management

• HRAC Group: 15 (VLCFA synthesis inhibitors).
• Strategies:
  • Rotate with Group 2 (ALS inhibitors) or Group 14 (PPO inhibitors).
  • Tank mix with herbicides of different modes of action (e.g., alachlor + glyphosate).
• Current Resistance Status: Limited resistance reported, primarily in annual grasses after continuous use.

FAQ

1. Can Alachlor 43% EC be used post-emergence?
   No; it requires uptake by germinating seedlings for efficacy.
2. What is the pre-harvest interval (PHI)?
   PHI varies by crop: 60 days for corn, 45 days for soybeans, 70 days for cotton.
3. Is Alachlor compatible with organic farming?
   No; synthetic herbicide prohibited in organic systems.
4. How does Alachlor affect rotational crops?
   Sensitive crops (e.g., beets, spinach) may require 4–6 months before planting; consult label for specifics.
5. Can it be applied through irrigation systems?
   Yes, via chemigation, but ensure uniform distribution and follow label rates.

Real-World Application Cases

• Midwestern Corn Fields: 3.0 L/ha Alachlor 43% EC + 2.0 L/ha atrazine controlled 90% of annual weeds through the growing season.
• Southeastern Soybeans: 2.5 L/ha Alachlor 43% EC reduced weed competition, increasing soybean yield by 15% compared to untreated plots.
• Cotton in Texas: 2.0 L/ha Alachlor 43% EC + 1.0 L/ha S-metolachlor provided season-long control of crabgrass and pigweed.

Packaging & Compliance

• Standard Packaging: 5L, 10L, 20L HDPE containers.
• Regulatory Support: COA, SDS, and MRL data available for global markets.
• Custom Solutions: Private labeling and formulation blending (e.g., alachlor + metribuzin premixes).