Metsulfuron Methyl 20% WP Herbicide Uses

Metsulfuron Methyl 20% WP is a selective, systemic, post-emergence herbicide from the sulfonylurea group, registered for use in India under the Insecticides Act, 1968. It is applied as a foliar spray, usually with a surfactant, to actively growing weeds in wheat, transplanted rice and sugarcane, and is absorbed through both the leaves and roots of target weeds at very low use rates. This page lists its mode of action, key benefits and the recommended crop-wise dosage as per CIB-registered labels.

Which Weeds Does This Control? (Field Identification Guide)

Not sure whether what's coming up in your wheat, rice or sugarcane field falls within this herbicide's control range? This guide helps you identify the weeds it targets so you can confirm before spraying.

Mode of Action

Metsulfuron methyl belongs to the sulfonylurea class of herbicides and works by inhibiting acetolactate synthase (ALS), an enzyme weeds need to produce the branched-chain amino acids valine, leucine and isoleucine. Without these amino acids, protein synthesis and cell division stop in the weed's growing points. It is systemic and effective at very low doses, taken up through both the leaves and roots of actively growing weeds and moved within the plant to the shoot and root tips. Treated weeds typically stop growing within a few days, show yellowing/purpling, and gradually die over one to three weeks, while the labelled crops tolerate the herbicide at the labelled dose and stage.

Features & Benefits

• Post-emergence, foliar-and-root-acting control effective at very low use rates per acre across three different crops — wheat, transplanted rice and sugarcane.
• Broad-spectrum activity on broadleaf weeds (Chenopodium album, Melilotus indica, Lathyrus aphaca, Anagallis arvensis, Vicia sativa, Cirsium arvense, Amaranthus viridis, Portulaca oleracea, Parthenium hysterophorus, Commelina benghalensis) plus sedges (Cyperus rotundus, Fimbristylis spp.) and a broadleaf aquatic weed (Ludwigia parviflora) depending on the crop.
• Wettable powder (WP) formulation, typically applied with a non-ionic surfactant to improve leaf coverage and uptake — check the current label for the surfactant rate.
• Low per-acre application volume makes it convenient for knapsack sprayers on smaller wheat and rice holdings.

Recommended Usage of Metsulfuron Methyl 20% WP Herbicide

The table below gives the CIB-registered dose, water volume, timing and waiting period per acre, based on the official CIB-registered per-hectare rate — see the note below the table for the conversion details. Always confirm against the current product label before use, including the surfactant addition rate.

Doses above are converted from the CIB-registered per-hectare rate (wheat and rice: 4 g a.i./ha, 20 g formulation/ha; sugarcane: 6 g a.i./ha, 30 g formulation/ha; 500–600 litres water/ha across all three) for Metsulfuron Methyl 20% WP. The sugarcane PHI of 346 days reflects the crop's long growing season, not an unusually persistent residue. Always confirm the current pack label/CIB registration and consult your local agricultural extension office before use and before harvest.

How to Use

1. Apply when weeds are small and actively growing, as per the timing on the current label; larger, well-established weeds are harder to control.
2. Mix the required quantity of Metsulfuron Methyl 20% WP into the spray tank and agitate well; add the surfactant specified on the current label at the correct rate, since it significantly improves leaf coverage and uptake for this herbicide.
3. In transplanted rice, drain standing water from the field or reduce it to a thin film before spraying, so the spray reaches weed foliage directly rather than being diluted by floodwater.
4. Spray uniformly using a knapsack or power sprayer fitted with a flat-fan nozzle, ensuring even coverage of weed foliage.
5. In rice, re-flood the field with a thin layer of water only after the spray has dried on the leaves, typically after a few hours, as per current label directions.
6. Avoid spraying during strong wind or if rain is expected within a few hours, as this can reduce weed uptake and control.

Precautions & Safety

• Wear appropriate PPE — mask, gloves, goggles and full-sleeved clothing — while mixing and spraying.
• Measure the small quantities required carefully, since this herbicide is used at very low per-acre doses and small errors can significantly affect the actual rate applied.
• Apply only at the correct crop stage and dose given above; do not drain the field immediately before spraying or re-flood too soon after in rice, as both reduce weed control.
• Store in the original, tightly closed container in a cool, dry place away from direct sunlight, food, feed and out of reach of children and livestock.
• Respect the labelled waiting period (PHI) for each crop — 80 days for wheat, 60 days for transplanted rice, 346 days for sugarcane — before harvest, and follow your local agricultural extension advice for the latest guidance.
• Metsulfuron methyl is an ALS-inhibitor (Group 2) herbicide; avoid repeated, back-to-back use of the same mode of action on the same field across seasons, and rotate herbicide groups as part of a resistance-management program.
• Follow label guidance on crop rotation before planting a different, sensitive crop in a treated field, since sulfonylurea residues can affect certain follow-on crops.
• 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.