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

Alachlor 43% EC (Emulsifiable Concentrate) is a selective pre-emergence herbicide from the chloroacetanilide family, designed to control annual grassy and broadleaf weeds in corn, soybeans, cotton, and other row crops. As a very long-chain fatty acid (VLCFA) synthesis inhibitor, it disrupts cell membrane formation in germinating weeds, leading to growth arrest and death. The 43% EC formulation (430 g/L alachlor) offers high solubility and ease of application, making it a staple in pre-emergence weed management programs.

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

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

Application Guide

Crop	Target Weeds	Dosage (L/ha)	Application Timing
Corn	Barnyardgrass, crabgrass	2.0–4.0	Pre-emergence (0–3 days post-planting)
Soybeans	Foxtail, lambsquarters	1.5–3.0	Pre-emergence (after planting, before crop emergence)
Cotton	Green foxtail, amaranth	2.0–3.0	Pre-emergence (before weed germination)
Sugarcane	Annual grasses, sedges	3.0–5.0	Pre-emergence (within 7 days of planting)

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

Broad-Spectrum Control: Effective against 20+ annual grassy and broadleaf weeds.
Residual Activity: 4–6 weeks of soil protection, reducing need for post-emergence applications.
Crop Safety: Selective in corn, soybeans, and cotton due to metabolic detoxification.
Cost-Effective: Low application rates (1.5–5.0 L/ha) compared to other pre-emergence herbicides.
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

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

Contact us for bulk orders or technical support. Optimize your pre-emergence weed control with Alachlor 43% EC—proven efficacy for modern row crop agriculture.