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Post-emergent paddy herbicide tank-mix

A common Telangana-Andhra post-emergent paddy spray combines three acetolactate synthase (ALS) inhibitors — all in HRAC Group 2 — to give one-shot control of grasses, sedges and broadleaf weeds at the 2-4 leaf weed stage. Typical brand combination: penoxsulam (Crystal Cream / Penoxa), bispyribac sodium (PI Nominee Gold / Indofil Nami) and metsulfuron + chlorimuron (DuPont Almix / Clormax).

Composition / Active ingredient

Three formulations, all ALS inhibitors:

  • Penoxsulam 2.67% OD — Triazolopyrimidine sulfonamide. Active on grasses and sedges.
  • Bispyribac sodium 10% SC — Pyrimidinyloxybenzoate (PI Nominee Gold). Active on grasses, sedges and broadleaves.
  • Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP — Sulfonylurea pair (DuPont Almix / Clormax). Active on tougher broadleaves and sedges.

Mode of action

All three actives inhibit acetolactate synthase (ALS), the first enzyme in branched-chain amino acid biosynthesis. They are classified together under HRAC Group 2. Despite acting at the same enzyme, the three molecules have different binding sites and partial spectrum differences, so the tank-mix gives broader, more reliable weed kill than any single product.

Target use and dose

The standard Telangana paddy tank-mix:

  • Penoxsulam 2.67% OD: ~400 ml/acre for grasses
  • Bispyribac sodium 10% SC: 50 ml/acre for grasses, sedges and broadleaf
  • Metsulfuron 10% + chlorimuron 10% WP (Almix / Clormax): 8 g/acre for tougher broadleaf and sedge cleanup

Applied at the 2-4 leaf weed stage / 12-20 DAT in transplanted paddy. The field is drained before spraying and re-flooded after 48-72 hours.

Safety and regulatory status

Stacking three Group 2 herbicides accelerates ALS resistance selection in weeds; this tank-mix should be rotated season-to-season with non-ALS modes of action — chloroacetamide Pretilachlor Craze (HRAC 15) at pre-emergence, the auxin + ALS Corteva Novixid Penoxsulam Florpyrauxifen (HRAC 4 + 2), and the new VLCFA inhibitor Ipfencarbazone Dinkar.

See also: Bispyribac Sodium Nominee Gold, Pyrazosulfuron Chempa, Novixid Penoxsulam Florpyrauxifen, Pretilachlor Craze, Halosulfuron Methyl Sempra.

References

  1. Nominee Gold — Bispyribac sodium 10% SC. PI Industries.
  2. Penoxa — Penoxsulam 2.67% OD. Crystal Crop Protection.