Herbicides should be used in combination with other methods of weed control such as cultural (i.e., use of crop residues as mulches, ), and .
When to apply
For effective weed control, different herbicides should be applied at different growth stages.
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
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
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: (pdf) from Direct Seeded Rice (DSR) in the Eastern Gangetic Plains of India
How to apply
- Always read and follow the instructions on the product label.
- Choose products suited for the type of weeds to be controlled and stage of crop or weed growth to which they should be applied.
- Ensure that field conditions are suitable for herbicide activity (e.g. soil must be moist, saturated or with standing water).
- Use the recommended rate and dilution.
- Use clean water for spraying.
- Calibrate sprayer and make sure spray nozzles are functioning properly. Use flat-fan nozzle for better delivery and surface cover.
- Uniformly apply product in the field by maintaining proper pressure, walking speed, and sufficient swath overlap.
- When post-emergence herbicides are applied in moist or saturated soil, re-introduce water into the plots one day after application, and maintain desired water depth.
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.