What are weeds? How can they affect the growth of crop plants?

Explanation

Weeds are unwanted plants that grow along with the main crops. They compete with the crops for water, minerals and sunlight and, therefore, reduce crop yield. Weeds may be poisonous to humans and domestic animals. Weeds attract pests and spread them to the crop plants. They spread very fast. It is, therefore, necessary to remove them from time to time. Different types of weeds grow with different crops. They also vary from place to place and from season to season. Amaranthus is a very common weed which grows with almost every crop.