Lesson Note On The Uses of Weeds and Methods of Weeds Control

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Cultural weed control: It involves the use of routine farm practices without the use of tools. These practices are

1. Mulching: Dry grasses are applied on ridges, vegetables beds or flat land. These will suppress or smothers weeds that have grown on such land and prevent others from sprouting.
2. Crop rotation: This is effective in controlling weeds associated with specific crops e.g milk weed is a serious problem on soyabeans and cowpea, but ineffective on cassava and maize. When such crops are moved away from the plot, the life cycle of the weed is interrupted.
3. Flooding: This method is effective in controlling weeds with under-ground perennial organs. The root of weeds are subjected to anaerobic condition (they will be deprived of oxygen) thereby killing them. E.g rice field.
4. Burning: This involves setting the vegetation on fire during land preparation. This method is effective in controlling weeds propagated by seeds and aerial portions.
5. Cover cropping: This involves planting fast growing leguminous crops such as mucuna utilis and calopo on land to act as cover and smother weeds. This method is effective in controlling weeds in plantation farm.

Others include the following Use of clean seeds, Close spacing and Close season.

Biological weed control: This is the use of natural enemies or living organisms e.g plants, animals, insects and micro-organisms to control weeds.

Preventive Weed Control

Under preventive method of weed control, the most effective is quarantine.

Quarantine are laws or regulations put in place by the government in order to prevent the entry of foreign pests, diseases, and weeds from one country to another. 

All imported agricultural materials must undergo quarantine by subjecting them to certain tests and inspections to be sure they do not contain weed seeds, fruits or their propagules before they are allowed entry into the country.

Integrated Weed Management (IWM)

In this method, all or some of the measures discussed above are combined together and used to combat weeds as no single method is absolute. Hence, it is the most effective of weed control method.

EVALUATION:

1. List four general methods of controlling weeds.
2. Explain how mulching and crop rotation can be used to control weeds.
3. Differentiate between pre-emergence and post-emergence herbicides.