ALS Enzyme Inhibition and Weed Spectrum
Pyrazosulfuron-ethyl belongs to the sulfonylurea chemical group (HRAC Group 2). It inhibits acetolactate synthase (ALS), an enzyme essential for synthesizing branched-chain amino acids (valine, leucine, isoleucine) in susceptible weed meristems.
Weed growth stops within 24 hours of application, followed by leaf chlorosis, necrosis, and complete weed collapse within 7 to 10 days.
- Sedges: Cyperus difformis, Cyperus iria, and Fimbristylis miliacea.
- Broadleaf weeds: Ludwigia parviflora, Sphenoclea zeylanica, and Eclipta alba.
- Low application rate: Delivers comprehensive weed suppression at extremely low grams of active ingredient per acre.
- Crop selectivity: Paddy plants metabolize Pyrazosulfuron-ethyl rapidly, ensuring complete crop safety without stunting.
Water Management and Application Timing
Field water depth at the time of spraying and subsequent water retention are decisive for herbicide efficacy.
Applying when weeds are at the 1 to 2 leaf stage creates a continuous chemical barrier in the standing water layer.
- Application timing: Apply between 3 to 8 days after transplanting in transplanted paddy, or 5 to 10 days after sowing in DSR.
- Water depth: Maintain a 2 to 3 cm water layer in the field during application and hold water undisturbed for 4 to 5 days.
- Spray or sand mix: Can be sprayed using flat fan nozzles or mixed with dry sand or urea for uniform broadcast.
Official source
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Central Insecticides Board & Registration Committee ↗Related on KisanPe
Common questions
What is the active ingredient in UPL Saathi herbicide?
UPL Saathi contains Pyrazosulfuron-ethyl 10% WP, an ALS-inhibiting sulfonylurea herbicide for rice.
When should UPL Saathi be applied in transplanted rice?
Apply 3 to 8 days after transplanting in standing water (2 to 3 cm depth) when weeds are at the early germination stage.
Does UPL Saathi control sedges like Cyperus in paddy?
Yes, Pyrazosulfuron-ethyl is particularly effective against major paddy sedges including Cyperus difformis and Cyperus iria.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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