Bensulfuron-methyl
Bensulfuron-methyl: A High-Efficiency Herbicide for Paddy Fields
Bensulfuron-methyl is a sulfonylurea herbicide widely used for controlling broadleaf weeds and sedges in rice paddies. With excellent selectivity and low application rates, it has become a preferred choice for rice farmers worldwide.
Key Product Features
- Highly effective against troublesome weeds in paddy fields
- Low application rates (15-60 g ai/ha)
- Excellent crop safety for rice varieties
- Long residual activity (4-6 weeks)
- Environmentally friendly formulation
Technical Specifications
| Parameter | Specification |
|---|---|
| Chemical Name | Methyl 2-[[[[(4,6-dimethoxypyrimidin-2-yl)amino]carbonyl]amino]sulfonyl]methyl]benzoate |
| Molecular Formula | C16H18N4O7S |
| Molecular Weight | 410.4 g/mol |
| Appearance | White to off-white powder |
| Melting Point | 185-188°C |
| Solubility | 1.2 mg/L in water (20°C) |
| Formulation Types | Wettable powder (WP), Water dispersible granules (WG) |
Target Weeds
Bensulfuron-methyl effectively controls:
- Broadleaf weeds: Monochoria vaginalis, Ludwigia prostrata, Rotala indica
- Sedges: Cyperus difformis, Scirpus juncoides, Eleocharis kuroguwai
- Annual weeds: Ammania spp., Lindernia spp.
Application Guidelines
| Crop | Application Timing | Rate (g ai/ha) | Method |
|---|---|---|---|
| Transplanted rice | 3-7 days after transplanting | 30-45 | Water surface application |
| Direct-seeded rice | 1-3 leaf stage of weeds | 30-45 | Water surface application |
Bensulfuron-methyl FAQ
What is the mechanism of action of Bensulfuron-methyl?
Bensulfuron-methyl is an acetolactate synthase (ALS) inhibitor. It works by blocking the ALS enzyme, which is essential for branched-chain amino acid synthesis in plants. This inhibition eventually leads to cessation of cell division and plant growth.
How long does Bensulfuron-methyl remain active in the soil?
The soil half-life of Bensulfuron-methyl is typically 2-4 weeks, depending on soil type and environmental conditions. In flooded paddy conditions, it may persist longer (4-6 weeks) and provide extended weed control.
Can Bensulfuron-methyl be used in rotational crops?
Caution must be exercised with rotational crops. While rice shows excellent tolerance, some sensitive crops planted after rice may show injury if planted too soon. Always follow label recommendations regarding crop rotation intervals.
Safety and Environmental Profile
- LD50 (rat, oral): >5000 mg/kg (practically non-toxic)
- Ecotoxicity: Low toxicity to fish and aquatic organisms
- Soil mobility: Low to moderate (Koc 100-500)
- Degradation: Primarily microbial degradation in soil
Comparison with Other Herbicides
| Herbicide | Application Rate | Weed Spectrum | Residual Activity |
|---|---|---|---|
| Bensulfuron-methyl | 30-45 g ai/ha | Broadleaf weeds + sedges | 4-6 weeks |
| Butachlor | 1000-1500 g ai/ha | Grasses + some broadleaves | 3-4 weeks |
| Pretilachlor | 450-600 g ai/ha | Grasses + some broadleaves | 3-5 weeks |
Storage and Handling
- Store in original container in cool, dry place
- Keep away from food, feed and drinking water
- Wear protective clothing during handling
- Rinse empty containers thoroughly before disposal
Bensulfuron-methyl FAQ (Continued)
What are the symptoms of Bensulfuron-methyl on sensitive weeds?
Affected weeds typically show chlorosis (yellowing) of new growth within 5-7 days after application. This is followed by stunting, necrosis, and eventual death of the plant within 2-3 weeks.
Can Bensulfuron-methyl be mixed with other herbicides?
Yes, Bensulfuron-methyl is frequently mixed with grass herbicides like pretilachlor or butachlor to provide broad-spectrum weed control. Always conduct a jar test before tank mixing to check compatibility.
What water management is required for Bensulfuron-methyl application?
Maintain 3-5 cm of standing water in the field during and for 3-5 days after application. Do not drain water during this period as it reduces herbicide efficacy.
Resistance Management
To prevent weed resistance to Bensulfuron-methyl:
- Rotate with herbicides having different modes of action
- Use recommended rates - avoid underdosing
- Combine with mechanical weed control when possible
- Monitor fields for reduced control efficacy