Herbicides, also commonly known asweedkillers, arepesticidesused to kill unwantedplants.Selective herbicides kill specific targets, while leaving the desiredcroprelatively unharmed. Some of these act by interfering with the growth of theweedand are often synthetic mimics of naturalplant hormones. Herbicides used to clear waste ground, industrial sites, railways and railway embankments are not selective and kill allplantmaterial with which they come into contact. Smaller quantities are used in forestry, pasture systems, and management of areas set aside as wildlifehabitat.