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.

Uses

Triclopyr is a selective weedkiller used to control dicotyledonous weeds (i.e. broadleaf plants) while leaving monocotyledonous plants (mostly bulbs, grasses and conifers) unaffected, or to control rust fungus on soybean crops. In the USA, it is sold under the trade names Garlon, Remedy, Turflon, Weed-B-Gon (purple label), Brush-B-Gon among others, and in the UK as SBK Brushwood Killer. It is a major ingredient in Confront, which was withdrawn from most uses because of concerns about compost contamination from the other major ingredient, clopyralid.

Environmental effects

Triclopyr breaks down in soil with a half-life between 30 and 90 days. It degrades rapidly in water, and 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 nontoxic to bees and marginally toxic to fish (rainbow trout LC50 (96 hr) = 117 ppm). Garlon's fact sheet for their triclopyr ester product indicates that triclopyr is highly toxic to fish, aquatic plants, and aquatic invertebrates, and should never be used in waterways, wetlands, or other sensitive habitats. This is only for the triclopyr ester product, not for the triclopyr amine product.