What are weed also explain the …

Weeds are unwanted plants in the cultivated field. Example - Xanthium (gokhroo), Parthenium (gajar ghas), Cyperinus rotundus (motha).

Effects of weeds on crop plants:

1. The growth of weeds in the crop fields is harmful because they compete for food, space and light.
2. They take up nutrients and reduce the growth of the crop.
3. They spread crop pests and diseases by acting as alternate host to insects and microorganisms.
4. Some weeds may produce toxic substance which may interfere with the growth of crop plants.

Therefore, removal of weeds from cultivated fields during the early stages of crop growth is essential for a good harvest.

The process of removing the weeds from crop field is called weeding.

Methods of controlling weeds:

1. Mechanical methods: Weeds can be controlled by mechanical methods like uprooting or ploughing with trowel or khurpi.
2.  Chemical methods: They can also be controlled by using herbicides or weedicides. Some common weedicides are 2,4-D, Atrazine and Isoproturon.
3. Cultural methods: They include proper bed preparation, timely sowing of crops, intercropping and crop rotation.
4. Biological control: Biological control of weeds involves the deliberate use of insects or some other organisms which consume and specifically destroy the weed plants like eradication of Opuntia cactus by using the  cochineal insects in Maharashtra and Tamil Nadu.