Considerations for using chemical controls for invasive plants in the Arden Woods:
For clarity: when treating invasive plants, we use generic glyphosate, not Round-Up. The adjuvants that are most hazardous to amphibians are surfactants in the proprietary formula of Round-UP. Glyphosate, (the active ingredient) can be bought as a single ingredient without those surfactants. Glyphosate is preferred because it is taken into the target plant’s vascular system preventing it from spreading to other plants and the environment, it binds with the soil particles and does not leach into the water table, and it does not last in the environment very long. (half-life depends on conditions and can range from 35 to average 47 days up to 197 days depending on microbial activity)
We use glyphosate as stump treatment and foliar sprays. Stump treatment is dabbing a small amount (measured in drops) with an applicator or a foam brush to a cut stem. It is applied so that the plant will not re-sprout and we don’t have to go back and retreat the same areas. The chemical can translocate within the plant and kill the root system making it more effective. In certain areas it’s best to leave the root structure in place and chemical treatment allows for this. We don’t disturb the soil structure or leave viable root fragments behind which is a benefit.
In foliar sprays, we limit the spray area by pulling areas of light growth until we reach a concentrated area of invasive plants reducing the area we spray and making sure the chemical will only hit target plants.
We foliar spray only when conditions are favorable (no wind, no rain predicted, correct temperature, correct timing and season for vulnerability of the plant) and spring ephemeral plants will not be affected.
Most recently, Arden’s foliar spraying has been done by a professional land manager with a pesticide applicator’s license. In April, I earned a pesticide applicator’s license out of an abundance of caution. It wasn’t necessary because glyphosate is not a restricted-use herbicide but learning about safe procedures and how to limit pesticide use was very useful.
In March 2015, World Health Organization’s International Agency for Research on Cancer (IARC) ranked glyphosate as a “probable” carcinogen. There are issues with this report. The ruling was directed at industrial practice not our limited practice. In the article listed here, from Reuters (I choose Reuters because of their reputation for neutrality and accuracy) dated October 2017, the reporterdetails instances in the IARC report where new information about the glyphosate not being likely to cause cancer was ignored. Quoting from the same Reuters article:
A year after IARC issued its evaluation, a joint United Nations and World Health Organization panel reviewed the potential for glyphosate in food to cause cancer in people. It concluded the weedkiller was "unlikely to pose a carcinogenic risk to humans."
The U.S. Environmental Protection Agency, which first assessed glyphosate in the 1980s and has reviewed it several times since, says it has “low toxicity for humans.” TheEuropean Food Safety Authority and the European Chemicals Agency, which advise the 28 members of the EU, have also assessed glyphosate within the past two years and ruled it safe.
Use of any herbicide is our last resort. I believe that limiting chemical use is essential. I prefer organic food because I don’t like the chemicals and believe that organic farming better for the earth. But Arden has a massive task maintaining the ecology of our Arden woods. We use glyphosate very differently than industrial use, applying very little chemical to treat specific plants that we isolate as much as possible. It’s nearly pointless and inefficient for me to go around attempting to pull out all the poison ivy along the paths because it re-sprouts from the remaining root system. It’s damaging to the soil and neighboring plants to yank out mats of English ivy when a foliar spray could treat it. Uprooting burning bush and Norway maples is damaging to the soil structure, it is preferable to stump treat or the work is less effective and our minimal resources are gone retreating the same areas.
I know our efforts are making a difference because I’ve seen other unmanaged woodlands nearby that are a wreck, monocultures lacking native plants and tree canopies overwhelmed with invasive growth. It is an essential tool in our fight. Judicious and cautious use of herbicides is a standard in ecological restorationprofession.
Fate of glyphosate in environment:
The European Food Safety Authority, 2015 “unlikely to pose a carcinogenic hazard to humans”
The EPA has reviewed Glyphosate several times since the 1980’s and found that it has “low toxicity for humans”