Methods of Weed Control

Agricultural Science JSS1 Second  Term

WEEK  9

Methods of Weed Control

Performance Objectives

    1. List the methods of weed control.

    2. Briefly discuss the methods of weed control

Content

Weed can be controlled using the following methods:

1. Mechanical/Physical method

2. Chemical method

3. Cultural method

4. Biological method

1. Mechanical/Physical method: In this method, the weeds are physically or mechanically removed after they are established. There are different mechanical/physical methods of weed control and they are as follows:

i. Slashing with cutlass/ machete

ii. Mowing of weeds on lawns, plantation or farms. The mower used is fixed to a tractor or can be pulled by hand to move over the farmland.

iii. Flooding: This is the starving weeds air to discourage respiration. The farmland covered with weeds is flooded for a maximum period of 7weeks.

iv. Hand pulling: It is a slow method of pulling weeds by hand in the farm. It is used on small farmlands and very effective but time and energy-consuming.

v. Hoeing: This method involves the use of how to remove weed from the farm. It can also be time and energy-consuming.

2. Chemical method: This entails the use of chemicals in large mechanized farms to kill weeds. The chemicals used for this method are called HERBICIDES. They are sprayed either on the leaves of weeds or applied directly to the soil. There are two types of herbicides; SELECTIVE AND NON-SELECTIVE herbicides.

Selective herbicides are chemicals which kill or injure certain types of weeds which grow among crops. They only destroy the weeds. Examples are 2,4-D (Dichlorophenoxy acetic acid), potassium cyanate and cyanamide.

Non- selective herbicides are chemicals which kill indiscriminately all plants with which they come in contact with. They are poisonous to mammals and should be used with extreme care. Examples are grammozone, lead arsenate and sodium chlorate.

3. Cultural method:  In this method, cultural practices like crop rotation, mulching, burning of farmland, early planting, tillage and good spacing are used to reduce the growth of weeds on the farm.

Crop rotation is used when a weed is closely associated with a crop. In such a situation, the weed will die naturally when the crop is no longer on the farm.

Mulching is done by covering the surface of the soil with vegetative materials or plastic materials which will help to destroy weeds.

Early planting helps to control weed growth. By planting early, crops become fully grown before the weeds start growing.

Tillage is a cultural practice that exposes the roots of weeds for destruction by the intense heat of the sun and when herbicides are sprayed.

Good spacing and correct spacing of crops during planting help to reduce and control weed growth along crop rows. It also enhances the passage of machines during mechanical control of weeds.

4. Biological method: This method involves the use of living plants and animals to control weeds. Cover crops that grow fast and large can be used to overshadow weeds thereby reducing their growth. Cover crops like melon, groundnut and weeds like centrosema pubescens can be used for this purpose.

Insects can also be introduced into the farm to control the growth of weeds. These insects are first identified and then introduced to the areas to feed on a particular weed. Farm animals like cattle also help to control weed growth through grazing/pasturing.