How to control weeds
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.
Fact sheets: Chemical weed control | Cultural weed control