Allelopathy is transfer of chemicals from one plant to another. Allelopathy is a larger area of ecological and physiological processes. According to modern research, depending on different concentrations, allelochemicals have positive or negative effects on plants. Allelochemicals are also known as secondary metabolites, compounds like phenol, alkaloids, steroids etc. Allopathic studies are performed to find out the effects of allelochemicals on seeds to promote or inhibit seed germination. Allelochemicals are also effective herbicides, fungicides, insecticides, and plant growth regulators that are environmentally friendly. Despite the fact that allelochemicals have been used as environmentally friendly herbicides for decades, natural herbicides made from allelochemicals are extremely rare. Herbicides made from natural products have been the subject of numerous studies.