Herbicides should be used in combination with other methods of weed control such as cultural (i.e., use of crop residues as mulches, stale seedbed technique), and manual and mechanical weeding.

When to apply

weeds-herbicideFor effective weed control, different herbicides should be applied at different growth stages.

  • Pre-planting

Spray non-selective herbicides on existing vegetation to kill weeds before planting.

Examples of herbicides to use: glyphosate, paraquat*, glufosinate

Read: Using zero tillage for weed control during land preparation

 *Banned in some countries; check herbicide availability and regulations
  • Pre-emergence

Apply herbicides prior to weed emergence at 1−3 DAS/DAT. 

Examples of herbicides to use: 

    • for transplanted rice - butachlor, pretilachlor
    • for wet seeded rice - pretilachlor + fenclorim
    • for dry seeded rice - oxadiazon, pendimethalin, oxadiargyl
  • Post-emergence

Spray herbicides at 3−4 leaf stage of the weed.

Examples of herbicides to use: bisparybacbispyribac, fenoxaprop + safener, fenoxaprop + ethoxysulfuron, metsulfuron + chlorimuron, azimsulfurom, penoxsulam, penoxsulam + cyhalofop, bentazon, 2,4-D

Read: Knockdown and post-emergence herbicide in DSR (pdf) from Direct Seeded Rice (DSR) in the Eastern Gangetic Plains of India


Reminders when using herbicides

  • Always mix clean water with herbicides before application. Refrain from using muddy water as this reduces herbicide efficacy.
  • Ensure all equipment, such as spray tanks, booms, and nozzles are well-cleaned after every use.
  • Do not mix herbicides together unless recommended.
  • Apply herbicides at a recommended rate.
  • Remember to wear proper protective equipment (i.e., gloves, breathing mask, goggles, and protective clothing) when spraying.