Chlorimuron-ethyl Herbicide | Selective Pre- and Post-Emergence Weed Control

Technical Specifications

• Active Ingredient: Chlorimuron-ethyl (CAS No. 90982-32-4)
• Molecular Formula: C₁₄H₁₅ClN₄O₇S
• Mode of Action: Inhibits acetolactate synthase (ALS), blocking biosynthesis of branched-chain amino acids (leucine, isoleucine, valine).
• Formulation: 25% WP (Wettable Powder)
• Target Crops: Soybeans, peanuts, cotton, dry beans, chickpeas.
• Target Weeds:
  • Annual Broadleaf: Pigweed, lambsquarters, velvetleaf, morningglory, smartweed.
  • Perennial Broadleaf: Field bindweed, Canada thistle (suppression).
  • Grasses: Partial control of annual bluegrass.

Mode of Action

1. Uptake: Absorbed by roots (pre-emergence) and foliage (post-emergence).
2. ALS Inhibition: Binds to acetolactate synthase, halting biosynthesis of essential amino acids.
3. Growth Arrest: Disrupts cell division in meristematic tissues (shoot/root tips).
4. Symptom Timeline:
   • 5–7 days: Chlorosis (yellowing) of new growth.
   • 10–14 days: Stunted growth, leaf curling, necrosis.
   • 21–28 days: Complete plant death.

Application Guide

Application Tips:

• Water Volume: Use 200–300 L/ha for pre-emergence; 300–400 L/ha for post-emergence.
• Rainfastness: 4–6 hours after application.
• Soil pH: Avoid use in soils with pH >7.5 to prevent crop injury.

Key Advantages

1. Broad-Spectrum Control: Effective against 30+ broadleaf weeds in legume crops.
2. Low Dosage: 5–20 g a.i./ha, reducing chemical input costs.
3. Residual Activity: Up to 6 weeks of soil protection, minimizing weed flushes.
4. Crop Safety: Selective in soybeans, peanuts, and cotton when used at labeled rates.
5. Tank Mix Compatibility:
   • Common Mixes: S-metolachlor, pendimethalin, glyphosate (broadens spectrum to include grasses).
   • Synergy: Enhances control of glyphosate-resistant weeds (e.g., Palmer amaranth).

Safety & Environmental Notes

• Toxicity: Low acute toxicity to mammals (LD₅₀ > 5000 mg/kg); toxic to aquatic invertebrates.
• Environmental Impact:
  • Soil persistence: 30–90 days (half-life), depending on pH and microbial activity.
  • Risk of carryover to sensitive crops (e.g., cereals, crucifers).
• Storage: Store in cool, dry place; protect from moisture.

Resistance Management

• HRAC Group: 2 (ALS inhibitors).
• Strategies:
  • Rotate with Group 14 (PPO inhibitors), Group 15 (VLCFA inhibitors), or Group 4 (synthetic auxins).
  • Tank mix with residual herbicides (e.g., chlorimuron-ethyl + metribuzin) to delay resistance.

FAQ

1. Can Chlorimuron-ethyl be used in organic farming?
   No; it is synthetic and prohibited in organic systems.
2. How does Chlorimuron-ethyl affect rotational crops?
   Sensitive crops (e.g., wheat, barley, canola) may require 12–18 months before planting.
3. Is Chlorimuron-ethyl effective against glyphosate-resistant weeds?
   Yes, due to different mode of action; useful in resistance management programs.
4. Can it be applied through irrigation systems?
   Yes, via chemigation; ensure uniform distribution and follow label instructions.
5. What is the pre-harvest interval (PHI)?
   PHI is 60 days for soybeans, 90 days for peanuts; consult label for specifics.

Packaging & OEM Services

• Standard Packaging:
  • 100g, 500g, 1kg bags (WP).
  • 5kg, 10kg, 25kg drums for bulk orders.
• Custom Solutions:
  • Private labeling with multilingual artwork.
  • Regulatory support for global markets (COA, SDS, MRL data).
  • Custom blends (e.g., chlorimuron-ethyl + flumioxazin combinations).

Why Choose Chlorimuron-ethyl?

• Soybean and peanut producers
• Resistance management programs
• Regions with high broadleaf weed pressure
• Conservation tillage systems

How does Chlorimuron-ethyl differ from other sulfonylurea herbicides?

1. Target Crop Specificity

• Chlorsulfuron (wheat, barley) 3,
• Metsulfuron-methyl (rice, wheat) 4,
• Tribenuron-methyl (wheat, canola) 3.
  This specificity arises from rapid metabolic inactivation in soybeans, where it is detoxified via hydroxylation and conjugation within hours 715. In contrast, crops like wheat tolerate chlorsulfuron due to different detoxification pathways 7.

2. Weed Control Spectrum

• Chlorimuron-ethyl excels against broadleaf weeds (e.g., pigweed, velvetleaf) and sedges in soybeans 18. It shows limited activity against grasses, requiring tank mixes for broader control 8.
• Broader-spectrum sulfonylureas like metsulfuron-methyl or thifensulfuron-methyl control both broadleaf and grass weeds 46. For example, metsulfuron-methyl is effective against grasses like Echinochloa in rice 4.
• Niche sulfonylureas (e.g., nicosulfuron for corn) target grass weeds specifically 3.

3. Application Rates and Timing

• Chlorimuron-ethyl is applied at extremely low rates (5–20 g a.i./ha), particularly in post-emergence scenarios (1/8–3/16 oz ai/acre) 114. This aligns with the sulfonylurea family’s hallmark low-dose efficacy 6.
• Earlier sulfonylureas like chlorsulfuron require higher rates (10–20 g a.i./ha) and are often used pre-emergence 313.
• Timing sensitivity: Chlorimuron-ethyl’s post-emergence window is narrow (soybean 2–3 trifoliate stage), whereas metsulfuron-methyl can be applied later in rice 49.

4. Soil Residual Activity and Rotational Crop Safety

• Chlorimuron-ethyl exhibits moderate soil persistence (half-life 30–90 days), posing risks to rotational crops like corn, cotton, or cereals if planted within 12–18 months 589.
• Longer-residual sulfonylureas (e.g., chlorsulfuron, sulfometuron-methyl) persist for 6–12 months, restricting rotational options 37.
• Shorter-residual alternatives (e.g., thifensulfuron-methyl) degrade faster (half-life 1–2 weeks), allowing quicker crop rotations 7.

5. Environmental Behavior

• Soil mobility: Chlorimuron-ethyl’s high water solubility (4.5 g/L at pH 7) and low adsorption (Koc 30–170) make it prone to leaching in sandy soils 1014. This contrasts with metsulfuron-methyl, which has lower leaching potential 5.
• Degradation pathways: Chlorimuron-ethyl degrades via hydrolysis (faster in acidic soils) and microbial activity 1015. Other sulfonylureas like chlorsulfuron rely more on microbial degradation 7.
• Aquatic toxicity: Chlorimuron-ethyl is toxic to aquatic invertebrates, requiring caution near water bodies 10. Most sulfonylureas share low mammalian toxicity but vary in aquatic impacts 614.

6. Resistance Management

• Resistance risks: Chlorimuron-ethyl’s long-term use in soybeans has selected for ALS-resistant weeds (e.g., Amaranthus spp.) in some regions 515.
• Rotational strategies: Unlike metsulfuron-methyl, which is often tank-mixed with grass herbicides 4, Chlorimuron-ethyl requires rotation with Group 15 (e.g., S-metolachlor) or Group 14 (e.g., flumioxazin) to delay resistance 815.
• Cross-resistance: Weeds resistant to Chlorimuron-ethyl may also resist other Group 2 herbicides like chlorsulfuron 5.

7. Formulation and Compatibility

• Common formulation: Chlorimuron-ethyl is typically sold as 25% WP (wettable powder) 28.
• Tank mix flexibility: It pairs well with grass herbicides (e.g., fluazifop) or PPO inhibitors (e.g., fomesafen) to broaden spectra 8. In contrast, chlorsulfuron often requires pH adjustment for compatibility 3.
• Adjuvant requirements: Chlorimuron-ethyl benefits from non-ionic surfactants to enhance leaf adhesion, a practice less critical for soil-applied sulfonylureas like pendimethalin 814.

Key Takeaways