Equisetum arvense, commonly known as Mare’s Tail or Field Horsetail, presents one of the most formidable challenges in garden and landscape management. This ancient plant has survived for millions of years due to its highly specialized and resilient structure. Eradication often becomes a multi-year project requiring consistent effort once the plant establishes itself. Dealing with this tenacious weed necessitates a thorough understanding of its unique biology combined with specific, targeted removal techniques. Effective control relies not on a single method, but on a sustained, integrated approach that addresses both the visible plant and the extensive underground network.
The Biology That Makes Mare’s Tail Persistent
Mare’s Tail is notoriously difficult to eliminate because its survival mechanisms are deeply rooted, both literally and figuratively. The plant’s extensive subterranean rhizome system acts as a massive energy store, allowing it to regenerate rapidly even after the aerial shoots are destroyed. These rhizomes can penetrate the soil to depths of 4 to 6 feet, forming multiple layers of horizontal growth at intervals of about 12 inches. Merely removing the top growth does little more than temporarily weaken the plant, as the bulk of its resources remain protected deep underground.
The plant’s physical structure above ground also poses a significant barrier to conventional weed control methods. Its stiff, segmented stems and needle-like foliage are heavily impregnated with silica, sometimes containing up to 7.4% of the mineral. This high silica content provides structural rigidity but also creates a waxy, protective cuticle that is highly water-repellent. Most standard herbicides simply bead up and run off the surface, failing to penetrate the plant tissue and travel down to the rhizomes where they are needed.
Reproduction further complicates eradication efforts, as the plant relies on two primary methods of spread. While it produces spores on specialized fertile stems in early spring, its main mode of dispersal is vegetative through its rhizomes. The underground system is brittle and readily fragments, meaning any attempt at cultivation or digging that breaks the rhizomes can inadvertently multiply the problem. Even small segments, sometimes as short as 1.2 inches, are capable of sprouting into a new plant, turning simple weeding into a distribution system for the infestation.
Manual and Cultural Control Methods
Non-chemical control of Mare’s Tail requires a sustained effort focused on depleting the massive energy reserves stored in the rhizomes. Repeated cutting or snapping of the green aerial shoots is a direct way to starve the underground system. This process must be performed consistently throughout the growing season, preventing the plant from photosynthesizing and replenishing its stored sugars. The goal is to force the rhizomes to repeatedly use their reserves to produce new shoots until they are fully exhausted, a process that can take multiple years.
Exclusion techniques offer another effective cultural control method by completely blocking the sunlight the plant needs to survive. Laying down a thick, opaque covering, such as specialized weed fabric or black plastic sheeting, will suppress the growth over an entire season or more. For this method to succeed, the covering must be completely impenetrable to light and extend well beyond the edges of the visible infestation, as the rhizomes will attempt to grow out from under the exclusion zone to reach the sun.
Physical removal by digging is an option only when done with extreme care and thoroughness. Since every piece of rhizome can regrow, the entire area must be excavated to a depth of several feet, and all root fragments must be painstakingly removed. The excavated material should never be added to a home compost pile, as the rhizomes may survive and be redistributed; instead, they should be bagged for municipal disposal. Addressing underlying environmental factors is also helpful, as Mare’s Tail often thrives in damp, poorly drained, or acidic soils.
Effective Chemical Treatment Strategies
Chemical control of Mare’s Tail is challenging but possible when specialized application methods are employed to overcome the plant’s natural defenses. Broad-spectrum systemic herbicides, such as those containing glyphosate, are often the chemical of choice because they are absorbed by the leaves and translocated down to the extensive rhizome system. However, applying standard glyphosate products directly to the shoots is frequently ineffective due to the plant’s waxy, silica-coated cuticle.
To ensure the herbicide penetrates the plant’s surface, a non-ionic surfactant must be added to the spray mixture. A surfactant reduces the surface tension of the water-based spray droplets, allowing the solution to spread out and adhere to the waxy stem instead of rolling off. For maximum efficacy, the herbicide should be applied when the plant is actively growing, typically in late spring or early summer. This timing ensures the plant is drawing energy down to its roots, carrying the chemical with it.
A preparation technique called “bruising” or “crushing” the stems immediately before application significantly improves chemical uptake. Crushing the stems with a plank of wood breaks the protective cuticle, creating openings for the herbicide to enter the plant tissue directly. The herbicide can then be carefully painted or wiped onto the bruised stems, which minimizes the risk of drift onto desirable plants. Multiple applications over the season are required, as a single treatment rarely achieves complete control of the deep rhizome network.
Long-Term Suppression and Site Management
After initial control efforts, whether manual or chemical, long-term suppression focuses on making the environment unsuitable for Mare’s Tail regrowth. One effective strategy is to improve the overall health and structure of the soil. Mare’s Tail often colonizes sites with poor drainage and low fertility, so amending the soil with organic matter can create conditions that favor other, more desirable plants. Improving drainage, especially in perpetually damp areas, reduces the moist environment the weed prefers, making the site less hospitable for its return.
Consistent monitoring is a necessary part of the maintenance phase to prevent any relapse. New shoots must be removed immediately upon sight, as allowing them to grow enables the rhizomes to replenish their stored energy. Establishing dense, competitive planting in the cleared area is an excellent way to out-compete any residual rhizomes. Groundcover plants or a thick layer of mulch will deprive new Mare’s Tail shoots of the light they need to emerge and photosynthesize.