Mefenacet 50% WP Herbicide | Pre-Emergent Weed Control for Rice and Transplanting Crops

Technical Specifications

Mode of Action

1. Root & Coleoptile Absorption:
   • Taken up by germinating roots and coleoptiles of young weeds.
2. Lipid Biosynthesis Inhibition:
   • Blocks the synthesis of long-chain fatty acids, essential for cell membrane formation.
3. Symptom Progression:
   • 5–7 days: Stunted root growth and curled coleoptiles
   • 10–14 days: Complete inhibition of seedling emergence or necrosis

Application Guide

Application Best Practices

• Water Management in Rice:
  Maintain 3–5 cm standing water for 5–7 days post-application to enhance herbicide activation.
• Adjuvants:
  Add 0.5% v/v mineral oil adjuvant for improved soil adsorption in non-flooded conditions.
• Tank Mixes:
  • With bensulfuron-methyl for broadleaf weed control in rice
  • With metribuzin for combined grass and broadleaf suppression in oilseeds
• Weather Conditions:
  Apply in calm weather (wind speed < 10 km/h); avoid during heavy rainfall.

Key Advantages

1. Highly Effective Against Grassy Weeds:
   • Controls 20+ annual grass species, including barnyard grass and crabgrass.
2. Long Residual Activity:
   • Provides 3–4 weeks of residual control, reducing early-season weed competition.
3. Crop Safety in Flooded Systems:
   • Selective in transplanted rice when applied under proper water management.
4. Cost-Effective Solution:
   • Lower application rates compared to some acetanilide herbicides (e.g., alachlor).
5. Low Mammalian Toxicity:
   • LD₅₀ > 2000 mg/kg (rat); minimal risk to non-target terrestrial organisms.

Safety & Environmental Notes

• Toxicity:
  • Moderate toxicity to fish (LC₅₀ 0.1–1 mg/L); keep 50 m buffer from water bodies.
  • Low toxicity to bees (LD₅₀ > 100 μg/bee).
• Crop Rotation Restrictions:
  • Avoid planting sensitive crops (e.g., crucifers, beets) within 6 months of application.
• Storage:
  Store in a sealed container at 5–30°C, away from moisture and direct sunlight.

Packaging & Compliance

• Standard Packs: 1 kg, 5 kg, 25 kg multi-layer paper bags with PE liner
• Regulatory Status:
  • Registered in major rice-growing regions (China, India, Southeast Asia)
• Shelf Life: 2 years under recommended storage conditions

FAQ

• Can Mefenacet 50% WP control broadleaf weeds?
  Primarily targets grasses; use tank mixes with broadleaf herbicides (e.g., 2,4-D) for combined control.
• What is the pre-harvest interval (PHI) for rice?
  60 days from application to harvest.
• Is it compatible with organic farming?
  No, as it is a synthetic herbicide; consult organic certification standards.
• How to manage herbicide-resistant barnyard grass?
  Rotate with Group 1 (fenoxaprop) or Group 2 (cyhalofop) herbicides in subsequent seasons.
• Can it be used in direct-seeded rice?
  Yes, but apply 1–2 days after seeding with proper soil moisture (not waterlogged).

Field Performance

• Rice Trials in Vietnam:
  1200 g ai/ha + bensulfuron-methyl controlled 92% of barnyard grass, increasing grain yield by 18%.
• Vegetable Trials in India:
  1000 g ai/ha reduced weed density in transplanted cabbage by 80%, improving head size and quality.