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2,4-Dichlorophenoxyacetic acid is an organic compound with the chemical formula Cl 2 C 6 H 3 OCH 2 CO 2 H.It is usually referred to by its ISO common name 2,4-D. [4] It is a systemic herbicide that kills most broadleaf weeds by causing uncontrolled growth, but most grasses such as cereals, lawn turf, and grassland are relatively unaffected.
The other auxin now used in comparable amounts to 2,4-D is dicamba, where the 2019 figure was 30,000,000 pounds (14,000,000 kg). [7] It is a benzoic acid rather than a phenoxyacetic acid whose use has grown rapidly since 2016 as crops genetically modified to be resistant to it have been cultivated.
Dicamba is toxic to conifer species but is in general less toxic to grasses. [2] Dicamba is a synthetic auxin that functions by increasing plant growth rate, leading to senescence and cell death. [2] [11] The growth regulating properties of dicamba were first discovered by Zimmerman and Hitchcock in 1942. [12]
When 2,4-D was commercially released in 1946, it became the first successful selective herbicide, triggering a worldwide revolution in agricultural output. It allowed for greatly enhanced weed control in wheat, maize (corn), rice, and similar cereal grass crops, because it kills dicots (broadleaf plants), but not most monocots (grasses). The ...
Today, only R-dichlorprop (also called dichlorprop-p or 2,4-DP-p) and its derivatives are sold as pesticides in the United States. Dichlorprop is a carboxylic acid, and like related herbicides with free acid groups, it is often sold as a salt or ester. Currently, the 2-ethylhexyl ester is used commercially. The butoxyethyl and isooctyl esters ...
By the end of 1941 it was clear to the Templeman group that MCPA was one of the most active compounds tested but other auxin herbicides including 2,4-D were also effective. This work took place during World War II and was a case of multiple discovery .
In Canada, the use and sale of 2,4,5-T was prohibited after 1985. [5] The international trade of 2,4,5-T is restricted by the Rotterdam Convention. 2,4,5-T has since largely been replaced by dicamba and triclopyr. Human health effects from 2,4,5-T at low environmental doses or at biomonitored levels from low environmental exposures are unknown.
Formulation terminology follows a 2-letter convention: (e.g. GR: granules) listed by CropLife International (formerly GIFAP then GCPF) in the Catalogue of Pesticide Formulation Types (Monograph 2); see: download page. Some manufacturers do not follow these industry standards, which can cause confusion for users.