As one of the most inexpensive and oldest weed killers, 2,4-Dichlorophenoxyacetic acid (usually called 2,4-D) is a systemic herbicide that is widely applied all over the world. It is effective to selectively kill a variety of terrestrial and aquatic broadleaf weeds without affecting most grasses, such as cereals, lawn turf, and grassland. Nowadays, 2,4-D is widely used to treat unwanted vegetation in various areas. In the field of forestry, it is used for stump treatment, trunk injection, selective control of brush in conifer forests and used to kill weeds and brush along roadways, railways, and power lines which probably damage equipment or interfere with safe operation. Besides, it is applied to control aquatic weeds for the safety of boating, fishing and swimming or protection of hydroelectric equipment. It is also used to control the spread of invasive, noxious and non-native weed species by government and control various poisonous weeds such as poison ivy and poison oak. In addiction to the forestry use, 2,4-D can also be used as a supplement in plant cell culture media in laboratories as a dedifferentiation hormone.
