Clomazone 48% EC Herbicide | Selective Pre-Emergence Weed Control

Technical Specifications

• Active Ingredient: Clomazone (CAS No. 81777-89-1)
• Molecular Formula: C₁₂H₁₄ClNO₂
• Molecular Weight: 241.70 g/mol
• Mode of Action: Inhibits phytoene desaturase, blocking carotenoid synthesis.
• Formulation: 48% EC (480 g/L Clomazone)
• Physical State: Light yellow to amber oily liquid
• Solubility: 220 ppm in water at 25°C; soluble in acetone, xylene
• Vapor Pressure: 2.3×10⁻⁷ mmHg at 25°C
• pH Range: 5.0–8.0 (stable in agricultural waters)

Mode of Action

1. Soil & Root Uptake: Absorbed by germinating weed roots and young shoots.
2. Carotenoid Blockade: Inhibits phytoene desaturase, preventing lycopene and β-carotene synthesis.
3. Photosynthetic Disruption:
   • Chlorophyll lacks protective carotenoids, leading to photo-oxidative damage.
   • Shoots emerge white (albino) and fail to photosynthesize.
4. Symptom Timeline:
   • 3–7 days: Albino seedlings with no green pigmentation.
   • 10–14 days: Necrosis due to lack of photosynthetic activity.

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.
• Tank Mixes:
  • Soybeans: Clomazone 48% EC + S-metolachlor (enhances grass control).
  • Cotton: Clomazone 48% EC + acetochlor (broadens spectrum to broadleaf weeds).
• Soil Type Adjustments:
  • High organic matter (OM >3%): Use higher rates (0.8–1.2 L/ha).
  • Sandy soils: Lower rates (0.5–0.8 L/ha) to reduce volatility.

Key Advantages

1. Selective Albino Effect: Safe for crops like soybeans, which metabolize clomazone rapidly.
2. Residual Activity: 3–4 weeks of soil protection, ideal for early-season weed control.
3. Low Application Rates: 0.5–2.0 L/ha, reducing chemical input costs.
4. Broad-Spectrum Control: Effective against 20+ annual grassy and broadleaf weeds.
5. Rotational Flexibility: Shorter soil residual (15–30 days) compared to other pre-emergence herbicides.

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: 15–30 days (degrades via microbial action and photolysis).
  • Volatility risk in warm climates; may cause vapor drift to sensitive crops (e.g., crucifers).
• Storage: Store in cool, dry place; avoid temperatures >35°C to prevent degradation.

Resistance Management

• HRAC Group: 12 (carotenoid biosynthesis inhibitors).
• Strategies:
  • Rotate with Group 15 (e.g., S-metolachlor) or Group 2 (e.g., chlorimuron-ethyl).
  • Tank mix with herbicides of different modes of action to delay resistance.
• Current Resistance: Limited resistance reported, primarily in continuous soybean systems.

FAQ

1. Can Clomazone 48% EC be used post-emergence?
   No; it requires uptake by germinating seedlings for efficacy.
2. What is the pre-harvest interval (PHI)?
   PHI varies: 60 days for soybeans, 90 days for cotton, 120 days for tobacco.
3. Does Clomazone affect rotational crops?
   Sensitive crops (e.g., beets, spinach) may require 4–6 months; consult label for specifics.
4. Is Clomazone compatible with organic farming?
   No; synthetic herbicide prohibited in organic systems.
5. How to mitigate vapor drift risk?
   Apply in cool conditions (<25°C); use drift-reducing nozzles and avoid upwind application near sensitive crops.

Real-World Applications

• Midwestern Soybeans: 0.75 L/ha Clomazone 48% EC + 1.5 L/ha S-metolachlor controlled 90% of annual weeds through planting.
• Cotton in the Southeast: 1.0 L/ha Clomazone 48% EC reduced weed competition, increasing yield by 12%.
• Tobacco Fields in Kentucky: 1.2 L/ha Clomazone 48% EC provided season-long control of crabgrass and lambsquarters.

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 tank mix formulations (e.g., clomazone + acetochlor premixes).