What is weeds and how to control it ?

Weeds are the unwanted plants which growing with the crop.

The adverse effects of weeds are:

(i) Weeds are complete with the crops for soil nutrients, sunlight and space.

(ii) Weeds harbor insects, pests and microorganisms.

(iii) Some weeds release into the soil, poisonous substances that are harmful to plants, human beings and animals.

Thus, weeds decrease the quality as well as yield of agricultural produce. Therefore, it is necessary to remove them from time to time. Though most of the weeds are uprooted during the ploughing of fields but they reappear when the crop grows. Weeds are very difficult to eliminate because of their certain natural powers. Weed seeds germinate earlier, their seedlings grow faster and on maturity, they produce large number of seeds. Some weeds have broad leaves while other has narrow leaves.

What are the common weeds found in wheat and rice fields?

1. Amaranthus (chaulai)

2. Chenopodium (bathua)

3. Convolvulus (hiran khuri)

4. Wild-oar (javi)

5. Grasses (ghaas).

How to Control Weed?

The process of removing weeds from a crop fields is called weeding. The common methods applied to control weeds are manual or physical methods, cropping methods, chemical methods and biological methods.

1. Physical Methods:

Hand-weeding, tilling, mowing, burning, etc. are examples of physical methods of weed control. The most efficient physical method of weed control is hand weeding. However, this method is very laborious, time consuming and costly. Weeding can also be done by ploughing or with the help of implements like trowel (khurpa) or harrow.

2. Cropping Methods:

The cropping methods of weed control involve selecting a proper variety of crop which can successfully compete with the weeds. Some crops such as sorghum, cowpea can compete better with weeds while crops such as groundnut, lentil are poor competitors. The verities which are well adapted to a region whose seeds have good germination can compete better with weeds.

3. Chemical Methods:

The chemical methods involve killing of weeds by spraying certain chemicals called weedicides. Thus, weedicides are the chemical substances, which are used to destroy weeds present in a crop. Weedicides are also known as herbicides. Some of the common weedicides are:

a. MCPA [4-chloro-2-methyl phenoxy acetic acid]

b. Battachlor

c. 2, 4-D [2-4-dichlorophenoxyacetic acid]

d. TCA [trichloroacetic acid]

e. 2, 4, 5-T [2, 4, 5-trichlorophenoxyacetic acid].

In order to kill the weeds a solution of the weedicide is sprayed on the standing crops in the fields with the help of a sprayer. The weedicides kills the weeds selectively without damaging the crop. Weedicides are more effective in killing broad-leaved weeds. The removal of weeds from the growing curves facilitates harvesting and gives a high quality produce. The chemical method is easier, less time consuming and less costly than manual weeding.

4. Biological Methods:

In biological methods of weed control, a natural enemy of the weed plant is used. For the success of this method, it is necessary that the destructive agent must be highly specialized and should not harm the crop even under starvation conditions.