Glyphosate (Roundup) is the most common herbicide used for ecological restoration globally (about 40% of the time when herbicides are used).
Because glyphosate is used to often in environmental restoration projects with the aim to eliminate invasive species (here’s why focusing on invasive species can backfire), it’s important to understand the impacts of using it.
Many native plant enthusiasts and environmental workers consider glyphosate to be the “cheapest and quickest” way to kill native species. But at what cost?
How Glyphosate Harms Bees and Pollinators
Foundational PNAS research found glyphosate at field-realistic concentrations perturbs the gut microbiota of honey bees, altering core bacterial species and has also been detected in commercial honey (up to 163 μg/kg) and raw honey (up to 342 μg/liter), confirming real-world exposure, not just lab exposure. Follow-up work found this microbiome disruption can lead to disease outcomes that reduce pollinator fitness, including deformed wing syndrome and increased susceptibility to varroa mites.
Glyphosate Kills Microorganisms Essential for Plant, Animal, and Human Health
Use of glyphosate, even one time, even in small concentrations, causes significant shifts in the soil microbiome, which negatively impact plant, animal, and human health. Unfortunately, these effects accumulate over time, and
There’s a LOT to say about how glyphosate impacts microbiomes, and you can read more from Beyond Pesticides (which is a great site with a lot of well-documented articles on the environmental and health impacts of many kinds of herbicides and pesticides) at https://beyondpesticides.org/dailynewsblog/2021/10/glyphosate-kills-microorganisms-beneficial-to-plants-animals-and-humans/
How Glyphosate Threatens Monarchs and Non-Target Plant Species
Glyphosate usage has virtually destroyed the milkweed plants that young Monarch butterflies depend on. This is a widely cited driver of monarch population decline tied to glyphosate-resistant crop systems that allow near-total weed elimination in farm fields.
Glyphosate can be toxic to native plants, with spray concentrations as low as 0.1% reducing macrophyte growth (think of your typical herbaceous plants like milkweed). Note that the recommended concentration of glyphosate spray is 1-4%, which is 10-40 times more than the concentration needed to significantly harm native plants!
Glyphosate application intended to kill invasive plants can cause populations of native forbs to decline, thereby allowing for the establishment and spread of invasive species.
In other words, using glyphosate to kill native species ends up causing more harm to native species than had it not been used at all.
How Glyphosate Threatens Earthworms
According to the authors of a 2015 study on glyphosate’s effects on earthworms, “We demonstrate, that the surface casting activity of vertically burrowing earthworms (Lumbricus terrestris) almost ceased three weeks after herbicide application, while the activity of soil dwelling earthworms (Aporrectodea caliginosa) was not affected. Reproduction of the soil dwellers was reduced by 56% within three months after herbicide application. Herbicide application led to increased soil concentrations of nitrate by 1592% and phosphate by 127%, pointing to potential risks for nutrient leaching into streams, lakes, or groundwater aquifers. These sizeable herbicide-induced impacts on agroecosystems are particularly worrisome because these herbicides have been globally used for decades.”
This is horrifying when you understand the implications.
As an anecic (deep-burrowing) earthworm, Lumbricus terrestris (the common earthworm or nightcrawler) creates permanent, vertical burrows that can extend up to six feet deep into the ground. This behavior drives several vital ecosystem services, including creating essential soil structure and hydrology for ecosystems and agriculture, protecting nutrient cycles, providing soil fertility, promoting root growth, and supporting the food web.
Whatever positive effect you may think glyphosate is creating in an ecosystem, garden, or farm, it is doing far more damage by destroying earthworms and nutrient cycles.
How Glyphosate Harms Aquatic Life
Glyphosate diminishes the growth of microalgae and aquatic bacteria, and it persists in soil and air long enough that leaches into groundwater, runs off into streams and rivers, and continues to harm aquatic insects, birds, and other wildlife.
Concentrations as low as 0.1 mg/L can significantly reduce zooplankton diversity, disrupting the base of the aquatic food chain, which is insane when you realize that single application of glyphosate on a two-acre lawn would build up to more than 0.1 mg/L concentration if that property had a 10’x10′ pond.
Why We Should Not Use Glyphosate in an Attempt to Help Ecosystems
For all of the reasons cited above, and more, we should not be using glyphosate to help “restore” ecosystems.
No matter how bad you think invasive plant species are, they are not nearly as bad as the consequences of disrupting soil and aquatic microbiomes, destroying plankton communities in water, killing milkweed and countless other herbaceous plants, thus destroying habitat and food for insects, birds, and other wildlife, killing earthworms and disrupting soil nutrient cycles, and killing bees and pollinators that we rely on for pollinating food and our very survival.
I understand that many smart, kind, loving, empathetic people have used glyphosate in an attempt to help the environment. But that’s because they didn’t understand the impacts this toxic chemical has on the environment.
Now that you do know, you can never again use glyphosate and claim that you didn’t know.
Please share this information with someone you love, care about, and respect. And thank you for all that you do to care for this amazing planet and the incredible life that we all get to share here!
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