Triclopyr - WikiHQ

Triclopyr, also Trichlopyr, formally [(3,5,6-trichloropyridin-2-yl)oxy]acetic acid, is an organic compound in the pyridine family of herbicides that is used as a systemic foliar type of herbicide Triclopyr is an acetic acid derivative, and so a monocarboxylic acid, with a pyridyloxy substituent: specifically, a pyridin-2-yloxy group substituted by chloro groups at positions 3, 5, and 6.

<chem>CHNCl3O- Na+ + CH2Cl-C(O)OCH3 -> CHNCl3-O-CH2C(O)OCH3 + NaCl</chem>

In the second step, the methyl ester is hydrolysed under alkaline conditions, with an acidic work-up to afford the acid product.

<chem>CHNCl3-O-CH2C(O)OCH3 + NaOH -> CHNCl3-O-CH2C(O)O- Na+ + CH3OH</chem>

<chem>CHNCl3-O-CH2C(O)O- Na+ + H2SO4 -> CHNCl3-O-CH2C(O)OH + NaHSO4</chem>

Once the product has cooled, a decolorising agent is often added, such as NaClO or 30% H<sub>2</sub>O<sub>2</sub>.

History

Triclopyr triethylammonium (TEA) was first registered in 1979 in the United States for use as an herbicide in non-crop areas and forestry to control broadleaf weeds and woody plants. A year later, in 1980, a formulation containing triclopyr butoxyethyl ester (BEE) was registered for similar applications. Both formulations expanded their usage to turf sites in 1984, and in 1985, triclopyr BEE was specifically registered for use on rangeland and permanent grass pastures. In 1995, the triclopyr TEA formulation received registration for use on rice crops to manage broadleaf weed species.

Triclopyr's usage in the US in 2018 was , and has held at roughly this level since 1998, by USGS estimates. It is mostly used on pasture and hay, with a small but consistent use on rice.

Uses

As presented by the Wisconsin Department of Natural resources, triclopyr is a systemic herbicide and is believed selective in its control of dicotyledonous (broadleaf) weeds and woody plants, The guidance goes on to state that<blockquote>Triclopyr needs to be applied to plants that are actively growing. If there is flowing water at a treated site, higher concentrations or a repeated application may be required. the United States, Brazil, Canada, Morocco, Paraguay, South Africa and Southeast Asia. In the United States, it is sold under the trade names Garlon, Remedy, Turflon, Weed-B-Gon, Brush-B-Gon, and RoundUp Brush Killer, and in the United Kingdom as SBK Brushwood Killer. It is also a major ingredient in Confront. In addition to weed control, triclopyr has also been documented for use in controlling rust fungus on soybean crops.

Triclopyr undergoes relatively rapid breakdown in soil, primarily through microbial activity. Soil half-lives typically range from 8 to 46 days, with longer persistence observed in deeper, less oxygenated soils. Although triclopyr is considered mobile in soil, studies have indicated limited movement below depths of 15 to 90 centimeters. Its movement in soil is influenced by factors such as organic matter content and rainfall. As a systemic herbicide, triclopyr is absorbed by plants through both leaves and roots and tends to accumulate in active growth regions. The rate of breakdown within plants varies widely depending on the species; reported half-lives in plants range from 3 to 24 days, with some plants like barley and wheat showing more rapid degradation. It has been found nontoxic to bees

Garlon's fact sheet for a triclopyr ester—versus the triclopyr amine salt per se—indicates that further derivative to be highly toxic to fish, aquatic plants, and aquatic invertebrates, and so never used in waterways, wetlands, or other sensitive habitats.

References

External links

archived Triclopyr Technical Fact Sheet – National Pesticide Information Center
Triclopyr General Fact Sheet – National Pesticide Information Center
Triclopyr Pesticide Information Profile – Extension Toxicology Network