Chemical Class and Mode of Action
Pretilachlor belongs to the chloroacetamide chemical family (HRAC Group 15), functioning as a cell division and lipid synthesis inhibitor.
It specifically inhibits very-long-chain fatty acid (VLCFA) elongase enzymes in germinating weed seedlings, halting cell elongation and preventing weed coleoptile emergence.
- Chloroacetamide Chemistry: Selective pre-emergence herbicide with excellent crop safety in transplanted rice
- Weed Seedling Arrest: Kills emerging weed shoots and roots at germination before they breach the soil surface
- Selective Tolerance: Transplanted rice seedlings rapidly detoxify pretilachlor through natural glutathione S-transferase enzymes
- Soil Barrier: Forms a chemical seal in the top 1 to 2 cm of field mud, suppressing weed germination for 25 to 30 days
Target Weeds in Transplanted Paddy
Pretilachlor controls a wide spectrum of competitive grassy weeds, annual sedges, and broadleaves before they can establish.
Applying it early protects young rice seedlings from vegetative-stage nutrient competition.
- Grasses: Echinochloa crus-galli (barnyard grass), Echinochloa colona, and Leptochloa chinensis
- Sedges: Cyperus difformis, Cyperus iria, and Scirpus species
- Broadleaf Weeds: Ludwigia parviflora, Sphenoclea zeylanica, Eclipta alba, and Monochoria vaginalis
- Application Window: Applied at 0 to 3 days after transplanting before weed seeds begin germinating
Water Management and Application Methods
Pretilachlor requires continuous shallow standing water (2 to 3 cm) in the paddy field for 4 to 5 days after application to maintain the chemical barrier.
It can be applied as a foliar spray or mixed with clean dry sand or fertilizer and broadcast uniformly across standing water.
- Standing Water: Maintain 2 to 3 cm water depth; letting the field dry out breaks the herbicidal barrier and permits weed emergence
- Sand Mix Broadcasting: Mix recommended dose thoroughly with 15 to 20 kg of dry sand or urea per acre and broadcast evenly
- Spray Method: Apply using 150 liters of water per acre fitted with a floodjet or flat-fan nozzle
Official source
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Central Insecticides Board & Registration Committee ↗Related on KisanPe
Common questions
What is pretilachlor 50% EC used for in paddy?
It is a selective pre-emergence herbicide used to control germinating grasses, sedges, and broadleaf weeds in transplanted rice fields.
When should pretilachlor 50% EC be applied?
Apply within 0 to 3 days after transplanting rice seedlings into standing shallow water before weed seeds germinate.
Can pretilachlor be applied by mixing with sand?
Yes, it is commonly mixed with dry sand or urea and broadcast uniformly across fields holding shallow standing water.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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