Definition and biological necessity of weed control
Weeds are plants that grow out of place, competing aggressively with cultivated crops for sunlight, soil nutrients, water, and root space.
Weedicides provide rapid chemical suppression of unwanted vegetation, preventing crop yield reductions that can otherwise reach 30% to 50% in unmanaged fields.
- Definition: Chemical or biological formulations designed to kill or inhibit the growth of unwanted plant species.
- Resource protection: Conserves costly fertilizer inputs and irrigation water exclusively for standing crop plants.
- Labor reduction: Alleviates severe farm labor shortages during critical early intercultural weeding periods.
Major classifications and agricultural examples
Weedicides are classified according to their selectivity, application timing, and mode of movement inside plant tissues.
Understanding these distinctions prevents crop damage and ensures successful eradication of target weed complexes.
- Selective weedicides: Destroy specific weed species without harming the host crop (e.g., Atrazine in maize, Pendimethalin in pulses, Bispyribac Sodium in rice).
- Non-selective weedicides: Kill all green plant vegetation upon contact (e.g., Glyphosate, Glufosinate Ammonium, Paraquat Dichloride).
- Pre-emergence weedicides: Applied to moist soil after sowing but before crop or weed emergence to stop germinating weed seeds (e.g., Pretilachlor, Pendimethalin).
- Post-emergence weedicides: Applied onto actively growing weed foliage after crops have established (e.g., 2,4-D, Fenoxaprop-p-ethyl).
Application safety, spray equipment, and precautions
Successful herbicide application requires calibrated spray equipment and dedicated flat fan or floodjet nozzles to ensure uniform soil or foliar coverage.
Operators must maintain strict protective safety protocols to prevent chemical drift onto neighboring sensitive crops.
- Dedicated sprayer: Use a separate sprayer for weedicides to prevent accidental contamination when subsequently spraying insecticides.
- Spray nozzles: Always utilize flat fan or floodjet nozzles operated at low pressure to minimize fine airborne drift.
- Personal protective equipment: Wear rubber gloves, protective goggles, face mask, and protective footwear during preparation and spraying.
Official source
Check the latest rules, benefits and forms here. KisanPe is an independent platform and is not a government website.
ICAR - Directorate of Weed Research ↗Related on KisanPe
Common questions
What is the primary difference between selective and non-selective weedicides?
Selective weedicides destroy weeds while leaving the crop unharmed; non-selective weedicides kill all green vegetation they contact.
When should pre-emergence weedicides be applied?
Pre-emergence weedicides should be sprayed onto moist soil within 1 to 3 days after crop sowing, before crop and weed seeds germinate.
Why is nozzle selection critical when spraying weedicides?
Flat fan or floodjet nozzles produce uniform overlapping spray fans at low pressure, avoiding mist drift and ensuring complete surface coverage.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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