Skip to content

Pyrazosulfuron-ethyl (Dhanuka Chempa)

Dhanuka Chempa is a sulfonylurea herbicide for transplanted rice containing pyrazosulfuron-ethyl 70% WDG. It is one of the most widely used pre- and early post-emergent herbicides in Indian paddy, applied as a sand-broadcast at 3-5 days after transplanting or as a spray at 15-30 DAT.

Composition / Active ingredient

  • Active ingredient: Pyrazosulfuron-ethyl
  • Formulation: 70% WDG (water-dispersible granule)
  • Chemical class: Sulfonylurea (pyrazole-substituted)

Mode of action

Pyrazosulfuron-ethyl inhibits acetolactate synthase (ALS), blocking branched-chain amino acid biosynthesis. HRAC Group 2. Absorbed through both roots and emerging shoots, it translocates to growing meristems where it stops cell division. Visible chlorosis appears within 7-10 days and complete weed kill within 2-3 weeks.

Target use and dose

Standard dose is 12 g/acre (30 g/ha). Two application timings are practiced in Indian paddy:

  • Sand broadcast: 3-5 days after transplanting in 2-3 inch standing water
  • Foliar spray: 15-30 DAT at the 2-4 leaf weed stage with field drained then re-flooded

Target weeds include grasses (Echinochloa, Dactyloctenium), sedges (Cyperus iria, Fimbristylis) and broadleaves (Ammania, Monochoria, Ludwigia).

Safety and regulatory status

The product is selective only on rice; spray drift to broadleaf crops can cause severe injury. As a Group 2 sulfonylurea, it shares cross-resistance risk with Bispyribac Sodium Nominee Gold and Halosulfuron Methyl Sempra; rotation with chloroacetamide Pretilachlor Craze (HRAC 15) and the auxin + ALS mix Novixid Penoxsulam Florpyrauxifen (HRAC 4 + 2) protects long-term efficacy.

See also: Bispyribac Sodium Nominee Gold, Halosulfuron Methyl Sempra, Pretilachlor Craze, Novixid Penoxsulam Florpyrauxifen, Post Emergent Paddy Herbicide Mix.

References

  1. Chempa — Pyrazosulfuron-ethyl 70% WDG. Dhanuka Agritech.
  2. Chempa Herbicide. AgriVruddhi.