State whether the following statement is true or false. Rewrite the false statement correctly.
Introduction of fertilisers into the field is called biological control of weeds.
Solution:
Ans. False
The correct statement is as follows:
Introduction of such organisms into the field that consume or destroy the weeds is called biological control of weeds.
Biological control of weeds:
The weeds are unwanted plants that grow in the crop field with the crops and absorb most of the soil nutrients. The weeds are usually treated with chemicals. But in biological control method living agents are used to suppress the spread of weeds. These living agents can be bacteria, fungi, insects or other grazing animals.
Biological control involves using insects or other organisms that consume and destroy weeds and pests.
Ans. False
The correct statement is as follows:
Introduction of such organisms into the field that consume or destroy the weeds is called biological control of weeds.
Biological control of weeds:
The weeds are unwanted plants that grow in the crop field with the crops and absorb most of the soil nutrients. The weeds are usually treated with chemicals. But in biological control method living agents are used to suppress the spread of weeds. These living agents can be bacteria, fungi, insects or other grazing animals.
Biological control involves using insects or other organisms that consume and destroy weeds and pests.
For example: The prickly-pear cacti (Opuntia) are controlled by cochineal insects.
Aquatic weeds are controlled by the fish known as grass carp.
Ladybirds and dragonflies are useful in getting rid of aphids and mosquitoes.
Chemical methods:
Yes, we can control weeds by using certain chemicals called weedicides like 2,4-D [2, 4- Dichlorophenoxy Acetic Acid] . But, we should be careful that we spray them in a minimum amount. Huge amounts of such chemicals can harm the crops and has a chance to pollute the surrounding environment. Anyway, the most suitable technique to control them is by cutting them close to the ground.