Pyrazosulfuron Ethyl 10% WP Herbicide Uses

Pyrazosulfuron Ethyl 10% WP is a sulfonylurea-group selective herbicide, registered for use in India under the Insecticides Act, 1968, formulated as a wettable powder (WP). It is registered specifically for weed control in transplanted (puddled, lowland) rice, applied as an early post-emergence spray to control a broad spectrum of sedges, broadleaf weeds and young annual grasses that compete with the rice crop for nutrients, light and water during the critical early tillering stage. This page lists its mode of action, key benefits and the recommended dosage for transplanted rice as documented on manufacturer labels and cross-checked against published agricultural field-trial research.

Which Weeds Does This Control? (Field Identification Guide)

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

Mode of Action

Pyrazosulfuron ethyl belongs to the sulfonylurea class of herbicides. It acts by inhibiting acetolactate synthase (ALS), also known as acetohydroxyacid synthase (AHAS) — an enzyme essential for the biosynthesis of the branched-chain amino acids valine, leucine and isoleucine inside plant cells. By blocking this enzyme, the herbicide starves susceptible weeds of amino acids needed for protein synthesis and cell division, halting growth within hours of uptake, although visible symptoms — yellowing, stunting and eventual death of the growing point — take one to three weeks to appear fully. It is absorbed by both the roots and the foliage of germinating and emerging weeds and moves systemically within the plant, giving effective control even of weeds not fully covered by the spray droplets. Transplanted rice tolerates the herbicide at the recommended dose because the crop metabolises (detoxifies) it faster than the target weed species, giving pyrazosulfuron ethyl good crop selectivity when used as per the label.

Features & Benefits

• Broad-spectrum control of sedges, broadleaf weeds and young grasses in a single spray, reducing the need for multiple herbicides or repeated hand-weeding passes.
• Systemic uptake through both roots and foliage gives season-long weed control from a single early application, at a very low use rate (grams per acre) typical of sulfonylurea chemistry.
• Selective to transplanted rice at the recommended dose and application timing, allowing safe use directly over the standing crop without crop injury when label directions are followed.
• Reduces dependence on manual weeding labour, which is an increasingly costly and scarce input during the transplanted paddy season in Punjab.

Recommended Usage of Pyrazosulfuron Ethyl 10% WP Herbicide

The table below gives the recommended dose and water volume per acre, based on the manufacturer's product label as reproduced by major agri-input retailers, cross-checked against the target-weed spectrum reported in peer-reviewed field-trial research on transplanted rice. Always spray in the recommended water volume for uniform coverage, and confirm against the current product label before use.

Pyrazosulfuron Ethyl 10% WP is registered in India only for use in transplanted (puddled) rice — no other crop use is listed on the current label. The dose above (40–60 g/acre) is the manufacturer-listed label rate reproduced by major agri-input retailers, converted where necessary using 1 ha ≈ 2.47 acres. This is confirmed by the Government of India’s official CIB & RC list of approved herbicide uses, which registers Pyrazosulfuron Ethyl 10% WP for transplanted rice at 100–150 g product/ha (≈ 40–60 g/acre) in 500–600 litres of water/ha (≈ 200–240 litres/acre) — matching the label rate above almost exactly. The CIB list gives a waiting period (PHI) of 95 days for this use; always confirm the current PHI printed on your product label before use.

How to Use

1. Confirm your field is transplanted (puddled, lowland) rice — this herbicide's label covers this use only, and it is not recommended for direct-seeded rice or any other crop.
2. Maintain a thin film of standing water (about 2–3 cm) in the field at the time of spraying and for a few days afterward, as is standard practice for early post-emergence herbicides in transplanted rice, to aid even distribution and root uptake.
3. Since this is a wettable powder, first mix the recommended dose into a small quantity of water to make a smooth paste, then add this to the full spray tank volume while stirring continuously so it disperses evenly.
4. Spray uniformly over the field surface 3–7 days after transplanting, before weeds exceed the 2–4 leaf growth stage — applying later, once weeds are larger and more established, significantly reduces effectiveness.
5. Avoid draining the field or allowing heavy rainfall to wash the herbicide away within 24–48 hours of spraying, and do not tank-mix with other herbicides of a different chemistry unless specifically recommended on the label.
6. Do not use water drained from a treated field to irrigate other, non-rice crops, and avoid spray drift onto neighbouring fields growing broadleaf crops.

Precautions & Safety

• Wear appropriate PPE — mask/respirator, gloves, goggles and full-sleeved clothing — while mixing and spraying, and avoid inhaling the wettable powder dust while opening the pack.
• Use only in transplanted rice as per the registered label; sulfonylurea herbicides such as this one can cause severe injury to non-target broadleaf crops (vegetables, pulses, oilseeds) from drift or residue, so take extra care to avoid any spray drift onto neighbouring fields.
• Follow the recommended dose and application window strictly — both underdosing (poor weed control and greater risk of resistant weed populations developing over time) and overdosing (potential crop injury) reduce field performance.
• 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.
• Repeated, season-after-season use of the same herbicide site-of-action group can encourage resistant weed populations to develop; rotate with herbicides from a different mode-of-action group as part of an integrated weed-management program.
• 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.

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