Halosulfuron Methyl 75% WG Herbicide Uses

Halosulfuron Methyl 75% WG is a selective, post-emergence herbicide from the sulfonylurea chemical group, registered for use in India under the Insecticides Act, 1968, formulated as a water-dispersible granule (WG). It is registered specifically for the control of sedges — chiefly purple nutsedge (Cyperus rotundus) and Cyperus iria — in sugarcane, maize and bottle gourd. This page lists its mode of action, key benefits and the recommended dosage as per the official Central Insecticides Board & Registration Committee (CIB&RC) list of approved herbicide uses (Government of India), cross-checked against manufacturer labels.

Which Weeds Does This Control? (Field Identification Guide)

Not sure whether the weeds in your field match this herbicide's use case? This guide helps match weed identification to this herbicide's approved crop-wise uses.

Mode of Action

Halosulfuron methyl belongs to the sulfonylurea group of herbicides, an ALS (acetolactate synthase) inhibitor (Group 2 / Group B). It blocks the ALS enzyme, which plants need to synthesise the branched-chain amino acids (valine, leucine and isoleucine) essential for cell division and growth. With ALS activity blocked, cell division halts at the weed's growing points (meristems); susceptible sedges stop growing within a few days of application, then turn yellow and reddish before becoming necrotic and dying over one to three weeks — including significant suppression of the underground tuber system that makes nutsedge so persistent. The labelled crops tolerate halosulfuron methyl at the recommended dose because they metabolise (detoxify) the herbicide faster than the target sedges can, which is what gives the herbicide its crop selectivity.

Features & Benefits

• Targeted control of purple nutsedge (motha) and Cyperus iria — sedges that are notoriously difficult to manage with grass- or broadleaf-selective herbicides or hand-weeding alone.
• Suppresses the underground tuber (nutlet) system of purple nutsedge, helping reduce re-infestation in the following season, not just the visible top growth.
• Approved for three very different cropping systems — a long-duration cash crop (sugarcane), a cereal (maize) and a cucurbit vegetable (bottle gourd) — giving flexibility across a mixed cropping farm.
• Water-dispersible granule (WG) formulation mixes easily into the spray tank and is convenient to measure, store and handle compared to liquid concentrates.

Recommended Usage of Halosulfuron Methyl 75% WG Herbicide

The table below gives the recommended dose, water volume and waiting period per acre for each labelled crop, converted from the CIB&RC-registered per-hectare rate — see the note below the table for conversion details. Always spray in the recommended water volume for uniform coverage, and confirm against the current product label before use.

Halosulfuron Methyl 75% WG is registered in India for sugarcane, maize and bottle gourd — no other crop use is documented in the CIB&RC list. The doses above are converted from the CIB&RC-registered per-hectare rates (1 ha ≈ 2.47 acres): Sugarcane — 60–67.5 g a.i./ha, 80–90 g formulation/ha, 375 litres water/ha; Maize — 67.5 g a.i./ha, 90 g formulation/ha, 375 litres water/ha; Bottle gourd — 67.5 g a.i./ha, 90 g formulation/ha, 375 litres water/ha. Sugarcane's long waiting period (294 days) reflects its long cropping duration rather than any unusual toxicity concern — sugarcane is typically in the ground for close to a year before harvest. Always confirm the current product label and PHI/waiting period before use.

How to Use

1. Confirm your field is sown with sugarcane, maize or bottle gourd — this herbicide's label covers these three crops only.
2. Since this is a water-dispersible granule, first mix the recommended dose into a small quantity of water to make a smooth suspension, then add this to the full spray tank volume while stirring continuously so it disperses evenly.
3. Spray as a directed post-emergence application once purple nutsedge / Cyperus iria have emerged and are actively growing — young, actively growing sedges are controlled more effectively than mature, stressed ones.
4. Use a knapsack or power sprayer fitted with a flat-fan nozzle for uniform coverage, and spray during calm, dry weather — avoid spraying in windy conditions or when rain is expected within a few hours, as this reduces efficacy and increases drift.
5. Ensure good, even ground coverage since sedges often emerge in patches; avoid leaving gaps between spray swaths.
6. Do not tank-mix with other herbicides of a different chemistry unless specifically recommended on the label.

Precautions & Safety

• Wear appropriate PPE — mask/respirator, gloves, goggles and full-sleeved clothing — while mixing and spraying, and avoid inhaling the WG dust while opening the pack.
• Resistance of sedges and other weeds to ALS-inhibitor (Group 2/sulfonylurea) herbicides is a well-documented and increasingly common problem where the same mode-of-action group is used repeatedly; avoid season-after-season reliance on halosulfuron methyl alone, and rotate with herbicides from a different group as part of an integrated weed-management program.
• Follow the recommended dose and application window strictly — both underdosing (poor weed control and faster development of resistant weed populations) and overdosing (potential crop injury) reduce field performance.
• Respect the labelled waiting period (PHI) — 294 days for sugarcane, 45 days for maize and 46 days for bottle gourd — before harvest, and follow your local agricultural extension advice for the latest guidance.
• Store in the original, tightly closed container in a cool, dry place away from direct sunlight, food and feed, and out of reach of children and livestock.
• Wash hands, face and any exposed skin thoroughly with soap and water after handling or spraying, and change out of contaminated clothing before eating, drinking or smoking.

Brand names mentioned on this page are registered trademarks of their respective owners and are referenced here for identification purposes only; FarmMate is not affiliated with or endorsed by these brands. This page is for general information only — always consult your local agricultural extension office and confirm the current product label before use.