Methods of weed/pest Control

Weed control involves removal and preventing weeds from spreading quickly and causing damage to cultivated crops. Some very common methods of weed control are:


  1. PhysicalControl: These involve picking of weeds and insects from the crop/animal by hand. It is called Hand picking. It is most useful for large insects like grasshoppers but very difficult to use on large farmland or if the number of pest is high. ):- This is a slow and tedious method of controlling weeds. It is efficient in small farms. Regular weeding must be done using hand, cutlass or hoe during wet season when weeds tend to grow and spread rapidly. Other methods of physical control includes setting traps, use of scare crow, use of net, use of reflective plastic strips, use of empty tin cans.


  1. ChemicalControl: The most common method of controlling insect pest and weed is by the use of chemicals. Chemicals which are poisonous to insects and weeds are called insecticides and herbicides respectively. The insecticides are applied by spraying by the machine known as sprayers.
  1. BiologicalControl: These involve the use of natural enemies of insect pests and weeds against them. The natural enemies may be other insects that feed on them or on their laid eggs.  For example, beetle can successfully control water weed and water hyacinth by feeding on their stems and leaves, cat can control rat, chicken can control insect.


  1. Mechanical control (Use of Machines): It is use in large farms through the use of machines called cultivators or weeders to remove weeds efficiently and effectively. This

method is suitable in farms where the crops are well planted in rows.


  1. Cultural Control (Use of Cropping Systems): Crop rotation system is very useful, earl planting and timely harvesting in preventing weeds from growing and spreading. Also, cover crops can be grown to prevent weed growth. Cover crops have large leaves, spread very rapidly and thus can kill any young weed seedlings. Examples of cover crops are members of the bean family e.g. Mucuna and Centrosema


  1. What is biological control?
  2. Write short note on cultural control.
  3. Define natural enemies.
  4. Mention two examples of cover crops.
  5. Define the following: a. Physical control b. Chemical control c. Biological control
  6. Mechanical control d. Cultural control
  7. Chemicals which are poisonous to insects and weeds are called _____ and ______.
  8. What is weed control?
  9. Explain physical control of weed and pest.



  1. Which of these is very difficult to use if the number of pest is high A. chemical control B. physical control C. biological control D. cultural control?
  2. Pollution of water bodies can likely be reduced by A. washing of chemicals from farmland B. falling down of suspended chemicals in air with rain C. release of waste product of chemical producing industries D. adequate awareness by extension agents .
  3. _____ involve the use of natural enemies of insect pests and weeds against them
  4. physical control B. chemical control C. cultural control D. biological control.
  5. Which of the following is not a physical control methodA. Use of trapB. Use of net

C.Use of chemicalD.Hand picking

  1. Natural enemies of weed and water hyacinth is A. Beetle B. Ant C. Bees D. Spider.



  1. State and explain two of pest control method.
  2. Give two examples each the methods stated above.

See also






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