Smilax species, commonly known as Greenbrier or Catbrier, are aggressive, native woody vines that quickly dominate a landscape. These perennial plants are difficult to eliminate due to their tough, lignified stems and robust, deep underground storage system. Standard hand-weeding or simple cutting methods are often ineffective. The plant stores substantial energy reserves in its subterranean structure. Successful eradication requires persistent, targeted methods that focus on physically removing or chemically destroying the dense root system, addressing the source of its relentless regrowth.
Identifying the Problem Vine
Confirming the presence of Smilax is the first step toward effective control. The vines are characterized by tough, woody stems frequently armed with sharp spines or prickles, which can be green or brownish. These spines make manual handling challenging and necessitate heavy protective gear. The leaves are typically glossy green, alternately arranged, and often heart-shaped, ovate, or fiddle-shaped, with three prominent parallel veins. Many species use strong, wiry tendrils to latch onto and climb adjacent vegetation or structures, forming dense thickets. These climbing vines can reach heights of up to 30 feet, using trees and shrubs for support.
The most characteristic feature lies beneath the soil surface, where a network of knobby, segmented rhizomes and hard, tuberous structures exists. These subterranean organs function as energy storage units, allowing the plant to rapidly regenerate even after the above-ground growth is destroyed. This extensive root system is why simple top-growth removal results in determined re-sprouting.
Physical Removal Techniques
For smaller, younger infestations or where chemical use is a concern, manual extraction is a viable but labor-intensive option. Initial efforts should focus on safely cutting the above-ground vines near the soil line to remove the thorny biomass. Heavy-duty gloves and long sleeves are recommended to protect against the sharp spines. Once the vines are cleared, digging out the underground rhizomes and tubers begins. These storage organs are often found deep in the soil, sometimes down to two feet, and can be tough and woody.
Every piece of the knobby, segmented root system must be removed, as even small fragments can regenerate a new plant. This mechanical approach is best suited for isolated plants or newly established populations that have not yet developed an extensive underground network. Repeated cutting of new sprouts can eventually exhaust the plant’s stored energy reserves, but this requires intense vigilance over multiple growing seasons. Removing the top growth forces the plant to deplete its reserves, but this must be done immediately upon re-sprouting to prevent photosynthesis.
Effective Chemical Treatment Strategies
Chemical control is the most efficient method for managing large or well-established Greenbrier infestations. Systemic herbicides, which are absorbed by the foliage and transported throughout the plant, are necessary to reach the deep root structure. Products containing glyphosate or triclopyr are recommended for controlling woody perennial vines. Foliar application is most effective when the vine is actively translocating nutrients to the roots, typically in late summer or early fall.
Applying the systemic herbicide during this period allows the chemical to be pulled down into the rhizomes alongside the plant’s stored food reserves. A 10% solution of concentrated glyphosate is an effective concentration for foliar treatment. Since mature Smilax leaves often have a waxy coating that resists herbicide absorption, it is beneficial to first cut the established vines and then spray the tender, new regrowth. The young leaves lack the thick cuticle of older growth, allowing for significantly better uptake of the herbicide. The addition of a non-ionic surfactant can further help the chemical penetrate the leaf surface.
Targeting the Root System for Complete Eradication
To overcome the vine’s deep energy reserves and waxy leaves, the “cut-stump” method offers a direct means of delivering herbicide to the root system. This technique involves cutting the main vine stem close to the ground, typically within a few inches of the soil surface. The success of this method relies on the plant’s vascular system being immediately available to transport the chemical.
A concentrated, undiluted herbicide, such as one containing a high percentage of glyphosate or triclopyr, should be painted or brushed onto the freshly cut surface immediately after the vine is severed. This immediate application is necessary because the plant’s cut tissues can quickly form a protective seal, preventing the chemical from entering the vascular system. The herbicide is then drawn directly down into the knobby rhizomes and tubers. This targeted approach minimizes the risk of herbicide drift and damage to desirable surrounding plants.
Because Greenbrier is capable of persistent re-sprouting, it is necessary to monitor the area closely for any new shoots emerging from the root system. Any regrowth should be treated promptly with a follow-up spot application of the foliar spray or by repeating the cut-stump method on the new stems to ensure the complete exhaustion of the persistent root structure.