Buckthorn has become a highly invasive species across North America, aggressively outcompeting native vegetation and degrading natural habitats. This non-native shrub or small tree quickly forms dense thickets that shade out the forest understory, diminishing plant diversity. Effective buckthorn removal is necessary to restore ecological balance. This involves a strategic, multi-step approach combining identification, mechanical removal, targeted chemical control, and long-term maintenance.
Identifying Buckthorn and Optimal Timing for Removal
Accurate identification is the first step in successful removal, focusing on the two main invasive species: Common Buckthorn (Rhamnus cathartica) and Glossy Buckthorn (Frangula alnus). Common Buckthorn has sub-opposite leaves with finely toothed edges and distinct, arcing veins, and its twigs frequently end in a sharp, thorn-like spine. Glossy Buckthorn leaves are typically oval with smooth, untoothed edges and a glossy surface with parallel veins. Both species display a characteristic orange inner bark layer when a branch is scraped or cut.
Timing is paramount for maximizing removal effectiveness, especially when using herbicides. The optimal period for chemical control is late summer through fall (July to October). During this time, the plant is actively moving energy and nutrients down to its roots for winter storage, pulling the herbicide deep into the root system. Mechanical removal, like hand-pulling, is best performed in early spring when the soil is moist, making it easier to extract the entire root system.
Physical and Mechanical Eradication Methods
For small buckthorn seedlings and young plants under a half-inch in diameter, hand-pulling is an effective, chemical-free method. This should be done when the ground is damp to ensure the entire root crown is removed, which prevents immediate re-sprouting. If the root crown breaks off, the plant will likely re-sprout.
Medium-sized shrubs (one to two inches in diameter) can be efficiently removed using specialized tools like weed wrenches or root jacks. These tools provide leverage to pull the entire plant, including the root system, from the soil with minimal disturbance. Complete root removal is necessary because cutting them without chemical treatment results in vigorous re-sprouting from the stump.
For large, established buckthorn trees exceeding two inches in diameter, the “cut and mow” technique is used when chemical treatment is not an option. This non-chemical approach involves cutting the plant near the base and then repeatedly cutting any re-sprouts that emerge throughout the growing season. This aggressive, multi-year cycle is designed to exhaust the carbohydrate reserves stored in the root system, eventually killing the plant.
Targeted Chemical Control Applications
Chemical control is often the most efficient method for mature, established buckthorn because it quickly kills the root system. The most commonly recommended active ingredients are glyphosate and triclopyr, which are applied directly to the plant rather than sprayed broadly. Glyphosate is a non-selective herbicide, while triclopyr is more selective and targets woody plants.
The cut-stump treatment is the standard for plants over half an inch in diameter. It involves cutting the stem as close to the ground as possible. The concentrated herbicide (typically 18-25% glyphosate or triclopyr) must be applied immediately to the freshly cut surface, targeting the cambium layer—the thin, living ring just beneath the bark. Immediate application is necessary because the stump quickly forms a barrier that prevents the absorption of the herbicide.
A basal bark treatment offers a less invasive chemical option for smaller stems up to about five inches in diameter. This method uses an oil-based formulation of triclopyr, applied directly to the intact bark around the base of the plant, typically from the ground line up to 12 to 18 inches. The oil allows the herbicide to penetrate the bark and be absorbed by the plant, making this treatment effective even during the dormant season. Always adhere to the manufacturer’s instructions and wear appropriate personal protective equipment.
Long-Term Management and Restoration
The removal of mature buckthorn is only the first phase, as the plant leaves behind a substantial seed bank in the soil. Recent research indicates that nearly all buckthorn seedlings will germinate within the first one to two years following the removal of the fruiting plants. This simplifies the long-term management timeline, but it still necessitates vigilant monitoring.
A continuous follow-up plan for at least three years is necessary to remove the flush of new seedlings that emerge after the initial removal. These new sprouts are easiest to manage through hand-pulling when they are small, but they will quickly take over the cleared area if ignored.
The most effective long-term strategy is to immediately plant native, shade-tolerant species in the cleared area to create competition. Planting native species, such as high-bush cranberry, American hazelnut, or grey dogwood, prevents the sun-loving buckthorn seedlings from establishing and helps stabilize the soil. Dense plantings of native trees and shrubs create heavy shade, which suppresses the growth of new buckthorn.