Is Tree Stump Killer Herbicide Safe Around Ponds?

The active ingredient in herbicides used specifically for killing trees and tree stumps is triclopyr butoxyethanol ester (triclopyr BEE), which is NOT safe to use around ponds, lakes, rivers, streams, any other waterways or bodies of water.

The product leaflet for Triclopyr 600 Herbicide issues the following warning:

PROTECTION OF WILDLIFE, FISH, CRUSTACEANS AND ENVIRONMENT

  • This product is highly toxic to fish and other aquatic organisms.
  • DO NOT contaminate streams, rivers or waterways with the chemical or used containers.

The US EPA has made the following statements about triclopyr BEE: “There is a high potential for acute risk to birds from triclopyr BEE.” and
Endangered species of birds, mammals, fish, aquatic invertebrates, estuarine/marine species, and plants may be affected by triclopyr BEE.”

Why Triclopyr Herbicide is Unsafe to Use Near Water

Triclopyr BEE is a synthetic auxin herbicide of the pyridyloxy‐carboxylate class, which mimics the plant growth hormone auxin. It causes uncontrolled growth and eventually the death of many sensitive broad-leaved plants.

These herbicides are effective even when present in the most minute quantities, and have been implicated in persistent herbicide contamination of commercial soil, compost manure and hay, leading to extensive damage of non-target plants and significant crop losses.

The chemical structure of Triclopyr butoxyethanol ester (BEE)

The herbicide Triclopyr BEE is sold in formulations such as Triclopyr 600, Garlon 600, Blackberry & Tree Killer, and Tri-Pic Herbicide.

Triclopyr BEE herbicides should NOT be used around waterways and bodies for the following reasons:

  • high mobility in soil, is easily washed away by rain or water runoff to non-target areas.
  • high persistence, will not break down easily and will remain active for very long periods of time. Triclopyr is primarily broken down by microorganisms in the top 12 inches of soil but when it gets deep into soil, where there’s less oxygen, it can persist for years. The half-life (time taken to break down to half of the original amount) of triclopyr in water with light is claimed to be around 1 day, but without light, such as in the bottom sediment layer in a pond or lake, it is stable in water with a half-life of 142 days. The soil half-life ranges from 8 to 46 days. In deeper soils with less oxygen, the half-life is longer, persisting for years.
  • moderate to high toxicity to fish and other marine species, toxic to birds.

Because triclopyr is considered mobile and moderately persistent there is a potential for it to contaminate drinking water.

When looking up information on the toxicity of the herbicide triclopyr, it is important to understand that it’s available in three different chemical forms, which are used for different purposes, and have different chemical properties, including toxicity levels.

The three forms of triclopyr are as follows:

  1. triclopyr BEE (butoxyethanol ester)
  2. triclopyr TEA (triethylamine salt)
  3. triclopyr acid

Only the butoxyethanol ester form of triclopy (triclopyr BEE) is used as a tree, blackberry and tree stump killer herbicide, and should never be used around water for the reasons outlined.

For a safer way to kill tree stumps, see the article – How to Kill a Tree Stump Without Poisonous Chemicals

References:

  • Triclopyr 600 Herbicide Leaflet – HerbiGuide
  • triclopyr BEE (butoxyethyl ester) – Thurston County
  • Strid, A.; Hanson, W.; Cross, A.; Jenkins, J. 2018 Triclopyr General Fact Sheet; National Pesticide Information Center, Oregon State University Extension Services. npic.orst.edu/factsheets/triclopyrgen.html.

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