Weed management‎ > ‎

Manual and mechanical

Manual method includes handweeding and use of hand tools. Mechanical method, on the other hand,includes the application of mechanized interrow cultivation and other mechanical method.

Manual method

Handweeding and the use of hand tools

- Examples of hand tools are hoes and sickles


  • Effective method of removing weeds
  • Practical and efficient method of removing weeds within rows or hills of rice where weeds cannot be controlled by other means


  • Extremely tedious and time consuming
  • It is not practical to use on large scale area of rice
  • It is difficult to distinguish weed seedlings from rice seedlings at early stage of growth and uprooting or damaging rice cannot be avoided. This occurs particularly in direct-seeded rice

Hand weeding is most useful on annual weeds and certain perennial weeds that usually do not regenerate from underground parts. It is a practical method of removing weeds within rows and hills where a cultivating implement cannot be used, but requires more labor than other direct weed control methods.

Handweeding of young weeds at the two-leaf to three-leaf growth stages is extremely difficult. Therefore, handweeding is generally delayed until weeds are large enough to be grasped easily. The method requires adequate soil moisture to ensure that weeds can be easily pulled. After weeding, the weeds usually have to be removed from the field to stop them from regenerating when left sitting in the field water.

Mechanical method

For mechanical weed control, straight row planting is essential. Example of tillage implements are rotary weeder and lithao. Weed control by tillage is achieved by:

  1. Burial. The weeds are buried in the soil thrown over them by the tillage tools. If the weeds growing points is buried, most annual weeds are killed by this method of weed control
  2. Disturbance of the roots. Passing of the tillage implement looses the soil or cuts the root system so weeds die of desiccation before they can reestablish.


  • Requires less time to wee rice than manual weeding.
  • Lower cost than manual weeding
  • Inability to control weeds growing close to crop plants.
  • Cannot be used effectively when the soil is too dry or too wet.
  • Improper use of tillage implements can damage the rice.

Mechanical weeding

Mechanical weeding is another direct method of weed control. For all mechanical methods, straight-row planting is essential.

Mechanized inter-row cultivation has the advantage that it aerates the soil, which often seems to help crop growth. However, mechanical weeding may be less effective than hand weeding because weeds within the crop rows are not removed. Competition from those weeds that survive can be harmful.

The challenges for mechanical weeding are that it requires row planted crops and it is very difficult if the soil surface is dry or if the soil sets hard.