Glyphosate is the main active ingredient in the world’s leading brand of grass and weed killer: RoundUp. But that’s not the only brand that features the herbicide. According to the National Pesticide Information Center at Oregon State University, over 750 products available for purchase in the U.S. contain the controversial ingredient.
According to EPA statistics, approximately 280 million pounds of glyphosate is applied to 298 million acres of crop land annually. Glyphosate is also a registered pesticide. In the home and garden sector, it’s the second-most used insect killer. But because of rising concerns over glyphosate’s (and the inert chemicals that make it more active in RoundUp) impact on human as well as animal and environmental health, more people are turning to natural weed-controlling alternatives.
Before listing some alternatives to glyphosate, it’s important to mention a few things about using a non-commercial weed-controlling ingredient or formula.
First of all, unbranded weed killers are not regulated by the EPA. As such, there may be little or no data as to the effectiveness and safety of the glyphosate alternative. Just because an ingredient or product is “all-natural” doesn’t necessarily mean it won’t cause harm if it gets in your eyes or nasal passages.
With that disclaimer out of the way, let’s take a look at some natural alternatives to Roundup. (Roundup contains 41% glyphosate; the remaining 59% is inert ingredients, which may make glyphosate more effective but potentially more toxic.)
Categories of Alternative Herbicides
According to a fact sheet prepared by two researchers at the University of Maryland, College of Agriculture and Natural Resources, there are 7 categories of alternative herbicides:
- Natural acids (vinegar + citric acids)
- Herbicidal soaps
- Iron-based herbicides
- Salt-based herbicides
- Phytotoxic oils (clove, peppermint, pine, citronella)
- Corn gluten
- Combination products
The UMD fact sheet focuses on vinegar-based alternatives to glyphosate. Vinegar (acetic acid, aka ethanoic acid), alters weed growth by acting on the cell membranes of a plant. This action causes the weeds to rapidly break down and dry out on contact.
But not just any household vinegar will do the trick. You may need to use herbicidal vinegar, which is much stronger than household vinegar. The former contains up to 20% acetic acid while the household variety contains just 5% acetic acid.
Products that contain 8% or less acetic acid are exempt from EPA pesticide registration, says the fact sheet, which states, “In sufficient quantities, acetic acid results in quick burn down of the plant, especially in bright sunlight. Products are non-selective, foliar sprays that kill most broad- leaved weeds.”
Despite its efficacy, vinegar may not work alone. It’s best to use a natural surfactant. The UMD fact sheet recommends yucca extract. This will help the vinegar stick to the weeds.
Read the UMD fact sheet to learn more about using vinegar to control weed growth.
All-natural dish soap brands such as Seventh Generation may be environmentally-friendly. But on their own, they don’t make for very strong weed killers. Just as glyphosate needs adjuvants (inert ingredients) to be more effective, natural soaps need help. So what can you add to natural soap to transform it into a lethal herbicide? For starters, use vinegar and add some salt.
Courtesy of SFGate.com, here’s a recipe for natural weed-killing success: Add 1 cup of salt and 1 tablespoon of dish soap to 1 gallon of vinegar, and mix thoroughly. Use a funnel to put the solution into a spray bottle. For best results, SFGate.com recommends using up vinegar that contains up to 20 percent acetic acid. And make sure the natural soap is not antibacterial.
And when you apply the vinegar/salt/soap, take precautions as if you’re using a very toxic herbicide: protect your hands and eyes and spray the plants on a hot, dry day.
Moreover, don’t expect natural alternatives to glyphosate to be one-and-done solutions; you will need to reapply these solutions.
MyGreenMontgomery.org, an eco-conscious website located in Montgomery County, MD, says that iron chelate is an active ingredient in several herbicide products, compatible with that County’s pesticide legislation.
Here’s how iron chelate works: Iron binds to a chelating agent. Together, the iron and binding ingredient is uptaken by the plant. If your grass is full of broadleaf weeds, iron chelate is absorbed into the weeds on a much larger scale than grass. This means there’s a better chance your lawn will be spared while the majority of the invasive weeds will be eliminated.
Iron chelate also works on moss, algae, and some fungal diseases in turf and garden beds, says MyGreenMontgomery.org, which adds that applying iron chelate is pet-friendly, once the grass is dry.
There’s more to essential oils than aromatherapy. The volatile organic compounds (the active ingredients) in plants, or “essence” of the plant (hence the term essential oils) possess strong properties. So much so they can kill weeds. Especially clove and peppermint oil, which makes for a potent herbicide/pesticide combination.
Try adding vinegar, salt and these two oils. Approximately 15 drops of each oil added to a tbsp of dish soap and a couple liters of vinegar may help keep weeds at bay.
A byproduct of milling corn, corn gluten (gluten is the glue-like proteins in wheat, corn and other grains) serves as an organic alternative to glyphosate. Effective if used before the weeds emerge rather than after they take root, corn gluten requires 20 pounds of it per 1,000 square feet of lawn, says TheSpruce.com. In addition to controlling weeds, corn gluten contains soil-benefiting nitrogen.