Pyroxasulfone 85% WG Herbicide Uses

Pyroxasulfone 85% WG is a pre-emergence / very-early-post-emergence herbicide from the isoxazoline chemical group, registered for use in India under the Insecticides Act, 1968, formulated as a water dispersible granule (WG). It is registered across three major crops — wheat, maize and soybean — for the control of grassy and select broadleaf weeds, applied to the soil before or just as weeds emerge. This page lists its mode of action, key benefits and the recommended dosage for each crop 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

Pyroxasulfone belongs to the isoxazoline chemical class within the VLCFA (very-long-chain fatty acid) synthesis inhibitor group of herbicides (Group 15 / Group K3). It works by blocking the elongation of very-long-chain fatty acids, which are essential building blocks for the waxy cuticle and cell membranes of a germinating weed seedling. Because this disruption happens at the point of germination and early shoot/root development, pyroxasulfone is primarily a soil-acting, pre-emergence herbicide (with activity extending into the very-early-post-emergence stage) — susceptible weeds are prevented from establishing before or just as they emerge from the soil, rather than being killed after visible growth like a typical post-emergence herbicide. For this reason, correct timing (application to moist soil before weeds emerge) and adequate soil moisture after application are critical to its performance.

Features & Benefits

• Broad-spectrum pre-emergence control of major grass weeds (Phalaris minor, Echinochloa, Eleusine indica) and several troublesome broadleaf weeds (Trianthema portulacastrum, Celosia argentea, Amaranthus viridis, Digera arvensis, Phyllanthus niruri) across three major crops.
• Season-long residual weed control from a single, well-timed pre-emergence application, reducing the need for repeated in-season sprays or hand-weeding.
• Group 15 (VLCFA-inhibitor) mode of action is a valuable resistance-management tool, being unrelated to the ACCase- and ALS-inhibitor herbicides commonly overused in wheat, maize and soybean.
• Registered across wheat, maize and soybean, making it a versatile option for farms growing more than one of these crops in rotation.

Recommended Usage of Pyroxasulfone 85% WG Herbicide

The table below gives the recommended dose, water volume and waiting period per acre for each 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.

Pyroxasulfone 85% WG is registered in India for use in wheat, maize and soybean — no other crop use is documented in the CIB&RC list. The dose above is the same across all three crops and is converted from the CIB&RC-registered per-hectare rate (127.5 g a.i./ha, 150 g formulation/ha, 500 litres water/ha; 1 ha ≈ 2.47 acres), which agrees closely with manufacturer label rates. The waiting period (PHI) differs by crop — Wheat 131 days, Maize 103 days, Soybean 94 days. Always confirm the current product label and PHI/waiting period before use.

How to Use

1. Confirm your field is sown with wheat, maize or soybean — this herbicide's label covers only these three crops.
2. Since this is a water dispersible granule (WG), first mix the recommended dose into a small quantity of water and stir to form a smooth suspension, then add this to the spray tank, half-filled with water, with continuous agitation; top up to the required water volume, maintaining agitation throughout spraying to keep the granules in suspension.
3. Apply as a pre-emergence spray to moist, well-prepared soil immediately after sowing and before the crop and weeds emerge — timing is critical, as pyroxasulfone needs adequate soil moisture to move into the weed germination zone and form an effective herbicide layer at the soil surface.
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, as this reduces the uniformity of the soil-applied herbicide layer and increases drift.
5. If the soil is dry at the time of application, a light irrigation shortly after spraying (where practical) helps activate the herbicide and improves weed control; avoid spraying just before heavy rain or flooding, which can wash the herbicide off-target.
6. Do not tank-mix with other herbicides of a different chemistry unless specifically recommended on the label, and avoid disturbing the treated soil surface (e.g. by tillage) after application, as this can break the herbicide layer and reduce weed control.

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.
• Pyroxasulfone belongs to Group 15 (VLCFA-inhibitor); avoid repeated, season-after-season use of the same mode-of-action group on the same field, and rotate with herbicides from a different group as part of an integrated weed-management program to delay resistance development.
• Follow the recommended dose and application timing strictly — both underdosing (poor weed control and faster development of resistant weed populations) and overdosing (potential crop injury, especially in light or sandy soils) reduce field performance.
• Do not apply to fields with a history of severe waterlogging, as pre-emergence herbicide performance and crop safety can both be affected under such conditions.
• Respect the labelled waiting period (PHI), which differs by crop — 131 days for wheat, 103 days for maize and 94 days for soybean — 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.