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

Clomazone 48% EC (Emulsifiable Concentrate) is a selective pre-emergence herbicide from the nitrile family, designed to control annual grassy and broadleaf weeds in soybeans, cotton, tobacco, and other row crops. As a carotenoid biosynthesis inhibitor, it disrupts photosynthesis by blocking pigment formation, leading to plant (albinism) and subsequent death. The 48% EC formulation (480 g/L clomazone) offers high solubility and ease of application, making it a strategic tool in pre-emergence weed management.

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

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

Application Guide

Crop	Target Weeds	Dosage (L/ha)	Application Timing
Soybeans	Crabgrass, pigweed	0.5–1.0	Pre-emergence (0–3 days post-planting)
Cotton	Foxtail, lambsquarters	0.6–1.2	Pre-emergence (before weed germination)
Tobacco	Annual grasses, sedges	0.8–1.5	Pre-emergence (1–2 days after transplanting)
Sugarcane	Green foxtail, amaranth	1.0–2.0	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.
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

Selective Albino Effect: Safe for crops like soybeans, which metabolize clomazone rapidly.
Residual Activity: 3–4 weeks of soil protection, ideal for early-season weed control.
Low Application Rates: 0.5–2.0 L/ha, reducing chemical input costs.
Broad-Spectrum Control: Effective against 20+ annual grassy and broadleaf weeds.
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

Can Clomazone 48% EC be used post-emergence?
No; it requires uptake by germinating seedlings for efficacy.
What is the pre-harvest interval (PHI)?
PHI varies: 60 days for soybeans, 90 days for cotton, 120 days for tobacco.
Does Clomazone affect rotational crops?
Sensitive crops (e.g., beets, spinach) may require 4–6 months; consult label for specifics.
Is Clomazone compatible with organic farming?
No; synthetic herbicide prohibited in organic systems.
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).

Contact us for technical data sheets or application consulting. Optimize your pre-emergence weed control with Clomazone 48% EC—proven efficacy for modern row crop agriculture.