How to control weeds for rice crop

Weed control is important to prevent losses in yield and production costs, and to preserve good grain quality. Specifically, weeds

• decrease yields by direct competition for sunlight, nutrients, and water
• increase production costs e.g., higher labor or input costs
• reduce grain quality and price
  For example, weed seeds in grain can cause the buyer price to be reduced.

Weed management should be practiced during specific stages of rice production:

During land preparation

Control of weeds during land preparation is crucial to reduce the amount of weed pressure in the field. Land preparation should start 3−4 weeks before planting. Plowing destroys weeds and remaining stubble from the previous crop. Weeds should be allowed to grow before the next cultivation. In addition, a level field helps retain a constant water level that controls weeds.

 For wet seeded rice

• Plow and harrow several times before planting. Depending on weed population, three or more operations can be done.
• Allow weeds to emerge for at least 2 weeks then kill by another shallow tillage. This reduces the number of weed seeds in the soil, and greatly reduces weeds for the subsequent crop.

 For dry seeded rice

• Allow weeds to emerge within 1−2 weeks, then kill them with either a non-selective herbicide or by light cultivation. 
• Spray herbicides, and perform manual and/or mechanical weeding.

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