The best horsetail weed killers are formulations that are specifically created to kill brush, vines, sedge, and other extremely hardy plants. The most effective formulations contain at least one of the following active ingredients: 2,4 D, Triclopyr, triethylamine salt, and halosulfuron-methyl. Weed killers with one or more of these ingredients are the only thing that will give you a chance at killing horsetail weeds down to the root.
The strongest products are non-selective, but there are horsetail killers that are safe to use in grass. The best horsetail weed killers are:
What to Look for in a Weed Killer for Horsetail
When choosing a horsetail weed killer, avoid common weed killers. Standard formulations of RoundUp and other popular weed sprays rely on Glyphosate as the main active ingredient. While this is fine for killing dandelions, horsetail is resistant to most weed killers.
Look for products labeled as “brush killers” and those that specialize in poison ivy control. These are some of the few weed killers that contain a blend of active ingredients strong enough to kill horsetail.
Most brush killers are non-selective, meaning they will kill any plant they touch, including grass. To kill horsetail growing in your yard, use a specially formulated brush killer that does not harm grass, or a selective sedge and nutgrass herbicide.
Best Horsetail Weed Killers
Below are the best weed killers for horsetail. These products are some of the few that give you a fighting chance against this deep-rooted and resilient invasive weed. When using any of these products, follow manufacturer directions carefully and keep in mind that it may take 1-2 weeks after application to see full results.
Crossbow sets the gold standard for killing horsetail because it pulls no punches. It combines 2 active ingredients (2,4-D and Triclopyr) to attack horsetail weeds. Horsetail has extensive root systems that can span a diameter of 20 feet and a depth of 5 feet. 2,4-D and Triclopyr are some of the only weed-killing ingredients that will attack horsetail rhizomes and actually destroy roots. Most other treatments are either ineffective or only kill the top of the plant, allowing it to resprout quickly.
Crossbow is also safe to use on most turfgrass species, allowing you to apply it even where horsetail has invaded your yard.
RoundUp is a household name in weed control because of their legacy of high quality products. While standard RoundUp will have little to no effect on horsetail because Glyphosate alone isn’t strong enough, RoundUp Poison Ivy Plus Tough Brush Killer can do the job. This is because, in addition to Glyphosate, the formulation includes both Triclopyr and triethylamine salt. In tandem, these three ingredients will attack horsetail and kill the plant completely.
Like standard RoundUp, this formulation does include Glyphosate, a non-selective weed killer that will kill any plant it touches, including lawn grasses. Apply only to horsetail growing in non-grassy areas. As with all horsetail killers, avoid applying it to any desirable garden plants.
Sedgehammer is probably the most turf-friendly of all the horsetail killers on this list, meaning it has the lowest chance of doing damage to your lawn. Unlike the others, the active ingredient in Sedgehammer is halosulfuron-methyl, which leaves almost all turf grasses unharmed. Initially designed for sedge and nutgrass control, Sedgehammer has shown strong results in killing horsetail, especially young plants under 6 inches, but it can be effective against mature plants as well.
Don’t get worried if the Sedgehammer doesn’t appear to be killing horsetail immediately. Although the top of the horsetail may still appear leafy and green, you should see a necrotic ring appear at the base of the horsetail plant within 1–2 weeks, as the Sedgehammer attacks the plant systems and kills it.
Like Sedgehammer, Ortho’s Weed-B-Gon formulation kills horsetail and is safe for use in lawns. Its formulation is different from brush-killing formulations, in that it pairs 2,4 D with, dimethylamine salt, MCPP-P, DMA salt, and Dicamba. In a New Zealand study, Dicamba was shown to be effective in killing horsetail in agricultural settings, so evidence suggests it may be another useful horsetail weed control tool.
While it contains lower concentrations of 2,4 D than some of the brush-killing formulations on this list, Weed-B-Gon is one of the best choices for attacking horsetail without harming your lawn.
With a formulation of 2,4 D and 2,4,5-trichlorophenoxyacetic acid, Brush-B-Gon contains an ingredient that destroys the cells that carry water and nutrients (2,4 D) with a powerful defoliant (2,4,5). This means that Brush-B-Gon destroys horsetail plant root and stalk systems at the same time it attacks horsetail leaves.
While Brush-B-Gon is extremely effective at killing horsetail, it’s best to avoid using it in grassy areas. Brush-B-Gon is non-selective and will kill several grass species on contact, including Bermuda and St. Augustine grass.
Our Choice for Best Horsetail Weed Killer
Crossbow is an extremely powerful formula that contains two of the most effective ingredients for killing horsetail. At the same time it serves as a powerful weed killer, it is also safe to use on most grasses, making it the perfect horsetail weed killer for use in your lawn. If you’ve got a horsetail infestation, try Crossbow first. Odds are, you won’t need any other product.
Weed Killer for Horsetail Weeds
Horsetail is notoriously hard to kill, but several weed killers on the market are capable of eradicating this weed. When searching for the best horsetail weed killer, look for products advertised as “brush killers.” Products in this category typically contain one or more of the following ingredients: 2,4 D, Triclopyr, triethylamine salt, and halosulfuron-methyl. These ingredients are the best at killing horsetail, and a high-quality brush killer will not only kill horsetail but leave your lawn grass undamaged.