Chemical Class & Mode of Action
Oxyfluorfen belongs to the diphenyl-ether family of contact herbicides. It acts by inhibiting the protoporphyrinogen oxidase (PPO) enzyme, resulting in toxic intracellular accumulation of protoporphyrin IX.
When exposed to sunlight, this accumulation generates high levels of reactive singlet oxygen that rapidly disrupt cellular membranes, causing cell leakage, rapid dessication, and weed necrosis within 2 to 4 days.
- Active Ingredient: Oxyfluorfen 23.5% w/w EC (Emulsifiable Concentrate)
- HRAC Classification: Group 14 (PPO inhibitor / cell membrane disruptor)
- Activity Type: Contact herbicide with significant residual soil activity; minimal translocation inside plants
- Light Activation: Requires ambient sunlight post-emergence to activate lethal lipid peroxidation
Approved Target Crops & Application Protocols
In India, Oxyfluorfen 23.5% EC is registered under the CIBRC for pre-emergence application in direct-seeded or transplanted onions, garlic, tea, potato, groundnut, and transplanted paddy.
When applied as a soil surface spray, it forms a continuous chemical barrier film on the soil. Germinating weed shoots contact this layer during emergence, absorb the active ingredient, and wither rapidly.
- Onion & Garlic: Apply pre-planting or within 2 to 3 days after transplanting before weed emergence
- Transplanted Rice: Apply within 3 to 5 days post-transplanting into standing water per label instructions
- Target Weeds: Amaranthus, Chenopodium, Portulaca, Echinochloa, and annual broadleaf weed seedlings
- Soil Preparation: Requires a smooth, clod-free, moist seedbed to establish an unbroken chemical barrier film
Crop Safety & Application Precautions
Because Oxyfluorfen is a contact membrane disruptor, direct foliar contact with standing green crop leaves can cause localized speckling or necrotic spotting. However, bulbs and true roots remain unaffected.
Do not disturb or cultivate the soil surface following a pre-emergence application, as physical hoeing breaks the continuous chemical seal, allowing buried weed seeds to germinate.
- Nozzle Selection: Use flat-fan or flood-jet nozzles operated at low pressure to deliver uniform soil coverage
- Soil Moisture: Adequate soil moisture at spraying is essential for optimal weed absorption
- Safety Gear: Wear chemical-resistant gloves, boots, protective eyewear, and coveralls during spraying
- PHI Compliance: Strictly observe statutory pre-harvest intervals registered with the CIBRC
Official source
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Central Insecticides Board & Registration Committee (CIBRC) ↗Related on KisanPe
Common questions
How does Oxyfluorfen herbicide work on weeds?
It inhibits the PPO enzyme; when exposed to sunlight, toxic oxygen radicals rupture weed cell membranes, causing rapid drying and necrosis of emerging weed seedlings.
Can Oxyfluorfen be used in onion crops?
Yes, it is one of the most widely registered herbicides for onion and garlic in India, applied pre-transplanting or immediately post-transplanting before weeds emerge.
Why shouldn't the soil be hoed after spraying Oxyfluorfen?
Hoeing or weeding breaks the continuous chemical barrier formed on the soil surface, exposing untreated soil and allowing buried weed seeds to germinate.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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