|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Appearance||White crystalline solid|
|Melting point||150 to 152 °C (302 to 306 °F; 423 to 425 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers. Clopyralid is in the picolinic acid family of herbicides, which also includes aminopyralid, picloram, triclopyr, and several less common herbicides. For control of creeping thistle, Cirsium arvense, a noxious, perennial weed, clopyralid is one of the few effective herbicides available. It is particularly damaging to peas, tomatoes, and sunflowers, and can render potatoes, lettuce, and spinach inedible. It does not affect grasses (family Poaceae).
Clopyralid is known for its ability to persist in dead plants and compost, and has accumulated to phytotoxic levels in finished compost in a few highly publicized cases. This first came to light in Washington, when during 2000 and 2001, residues of clopyralid were detected in commercial compost, and compost made at a municipal site damaged tomatoes and other garden plants planted in it. Word quickly spread to other local and state governments, and in 2002, DowAgro, the manufacturer of clopyralid, voluntarily deregistered it for use on domestic lawns in the US and it is banned in several US states, but it is found in consumer products in Europe such as Scotts Verdone Extra and Vitax Lawn Clear 2.
Clopyralid is licensed for lawn use in France and under these names: Bayer Jardin: Désherbant jeune gazon and Scanner Sélectif gazon Vilmorin: désherbant Gazon LONPAR. Brand names of clopyralid in the US market include Stinger, Transline, Reclaim, Curtail, Confront, Clopyr AG, Lontrel, Millennium Ultra, Millenium Ultra Plus and Redeem.
- Merck Index, 11th Edition, 2398.
- Staff, Virginia Tech Cooperative Extension. Revised May 14, 2012 Pyridine Herbicide Carryover: Causes and Precautions Archived 2016-11-30 at the Wayback Machine Accessed May 27, 2013
- Bob Hartzler, extension weed management specialist, Department of Agronomy, Iowa State University. February 21, 2006 Aminopyralid - New herbicide for pastures, roadsides, etc. Archived 2014-11-03 at the Wayback Machine Accessed May 27, 2013
- Moody, Oliver (23 February 2013). "Weedkiller banned in US 'is getting into compost and killing garden vegetables'". The Times. London.
- David E. Haskell , California Department of Pesticide Regulation Clopyralid in Compost[permanent dead link] 2003 Proceedings of the California Weed Science Society 55:163-166
- "Herbicide Resistant Weeds". Archived from the original on 2011-07-18. Retrieved 2011-03-07.