Appearance Fluffy solid Molar mass 256.46 g/mol Acidity (pKa) 2.68 | Formula C7H4Cl3NO3 Melting point 148 °C Soluble in Water | |
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IUPAC ID [(3,5,6-Trichloro-2-pyridinyl)oxy]acetic acid | ||
Triclopyr (3,5,6-Trichloro-2-pyridinyloxyacetic acid) is an organic compound in the pyridine group that is used as a systemic, foliar herbicide and fungicide.
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Uses
Triclopyr is used to control broadleaf weeds while leaving grasses and conifers unaffected or to control rust diseases on crops.
Triclopyr is effective on woody plants and is used for brush control in rights of way and defoliation of wooded areas. In the USA it is sold under the trade names Garlon and Release, and in the UK as SBK Brushwood Killer.
It is also used for broadleaf weeds, particularly Creeping Charlie (Glechoma hederacea). It is sold under the trade names Turflon, Weed-B-Gon (purple label), and Brush-B-Gon ("Poison Ivy Killer") for these purposes. It is a major ingredient in Confront, which was withdrawn from most uses due to concerns about compost contamination from the other major ingredient, clopyralid.
Triclopyr is formulated both as an ester and as an amine salt. The usual tradeoffs regarding effectiveness, drift, and toxicity to humans apply to these two formulations. It is chemically very similar to the herbicide which it generally replaces, 2,4,5-T, which was phased out in the U.S. in the 1970s amid toxicity concerns.
Environmental issues
Triclopyr breaks down in soil with a half-life of between 30 and 90 days. One of the byproducts of breakdown, trichloropyridinol, remains in the soil for up to a year. Triclopyr degrades rapidly in water. It remains active in decaying vegetation for about 3 months.
The compound is slightly toxic to ducks (LD50 = 1698 mg/kg) and quail (LD50 = 3000 mg/kg). It has been found non-toxic to bees and very slightly toxic to fish (Rainbow trout LC50 (96 hrs.) = 117 ppm).