Methods of Weed/Pest Control
Weed control involves the removal and prevention of weeds from spreading quickly and causing damage to cultivated crops. Some very common methods of weed control are:
Physical Control: These involve picking 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 pests is high.
This is a slow and tedious method of controlling weeds. It is efficient in small farms. Regular weeding must be done using a hand, cutlass or hoe during the wet season when weeds tend to grow and spread rapidly.
Other methods of physical control include setting traps, the use of scarecrows, the use of the net, the use of reflective plastic strips, use of empty tin cans.
Chemical Control: The most common method of controlling insect pests and weeds 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 with a machine known as a sprayer.
Biological Control: 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 eggs.
For example, beetles can successfully control water weeds and water hyacinths by feeding on their stems and leaves, cats can control rats, and chickens can control insects.
Mechanical Control (Use of Machines): It is used in large farms through the use of machines called cultivators or weeders to remove weeds efficiently and effectively. This method is suitable for farms where the crops are well planted in rows.
Cultural Control (Use of Cropping Systems): Crop rotation system is very useful, as early planting and timely harvesting prevent 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
GENERAL EVALUATION/REVISION QUESTIONS
- What is biological control?
- Write a short note on cultural control.
- Define natural enemies.
- Mention two examples of cover crops.
- Define the following: a. Physical control b. Chemical control c. Biological control
- Mechanical control. Cultural control
- Chemicals which are poisonous to insects and weeds are called _____ and ______.
- What is weed control?
- Explain the physical control of weeds and pests.
THEORY
- State and explain two of pest control methods.
- Give two examples each of the methods stated above.
See also