Chemistry:Swep
Swep or MCC is a carbamate herbicide discovered in the 1960s,[1] formerly used to control annual weeds and grasses in rice, potatoes, cotton, corn, peas, peanuts, and sorghum, and is no longer used in the USA.[2] Notably, swep must be applied at high rates per acre compared to other herbicides, 3.75-5.62 kg/Ha (3.35-5.01 lbs/ac.).[3]
Mechanism of action
Swep interferes with cell division and growth.[3]
Environmental behaviour
Swep is relatively volatile, with a vapour pressure of 187 mPa, so swep can be lost to the atmosphere.[4] In a laboratory soil degradation test, the amount of swep in soil halved in 21 days. Degradation is by microbial breakdown, not by chemical means.[5]
3,4-Dichloroaniline (DCA) is swep's primary metabolite, roughly one part in six of which is further transformed to 3,3',4,4'-tetrachloroazobenzene (TCAB).[5] DCA can be broken down (mineralised) by many microbes, including strains of variovorax, sphingomonas and achromobacter. A "consortium" of a couple of bacteria strains can convert swep to DCA and then break down the 3,4-DCA.[3] DCA is an intermediate, and does not accumulate in meaningful quantities are swep decomposes.[5]
Uses
Swep is usually formulated as an emulsifiable concentrate (EC).[1]
Swep can control grasses, broadleaf weeds, and sedges,[1] including barnyard grass, purslane, chenopodium and trifoliate grass.[4]
It is used on cereals and vegetables[1] including leek, green onion and garlic.[4]
References
- ↑ 1.0 1.1 1.2 1.3 Hertfordshire, University of. "Swep". Pesticide Properties Database. https://sitem.herts.ac.uk/aeru/ppdb/en/Reports/3631.htm.
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedhaz - ↑ 3.0 3.1 3.2 Zhang, Long; Hang, Ping; Zhou, Xiyi; Dai, Chen; He, Ziyi; Jiang, Jiandong (7 January 2020). "Mineralization of the herbicide swep by a two-strain consortium and characterization of a new amidase for hydrolyzing swep". Microbial Cell Factories 19 (1): 4. doi:10.1186/s12934-020-1276-9. PMC 6945715. https://pmc.ncbi.nlm.nih.gov/articles/PMC6945715/. Retrieved 9 February 2026.
- ↑ 4.0 4.1 4.2 An, Zexiu; Bo, Xiaofei; Mei, Qiong; Wei, Bo; Xie, Ju; Zhan, Jinhua; He, Maoxia (10 April 2022). "Theoretical insights into the degradation of swep by hydroxyl radicals in atmosphere and water environment: Mechanisms, kinetics and toxicity". Science of The Total Environment 816. doi:10.1016/j.scitotenv.2021.151651. https://www.sciencedirect.com/science/article/abs/pii/S0048969721067279. Retrieved 9 February 2026.
- ↑ 5.0 5.1 5.2 Bartha, R.; Pramer, D. (July 1969). "Transformation of the herbicide methyl-N-(3,4-dichlorophenyl)-carbamate (Swep) in soil". Bulletin of Environmental Contamination and Toxicology 4 (4): 240–245. doi:10.1007/BF01557982. https://link.springer.com/article/10.1007/BF01557982. Retrieved 9 February 2026.
External links
- Swep in the Pesticide Properties DataBase (PPDB)
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