Buckthorn

What is Buckthorn?
Buckthorn is a non-native, invasive shrub originating in northern Eurasia. It has been distributed by nurseries in this country since at least the nineteenth century. For many years, Buckthorn has been used as a hedge plant, most often in residential lots. Recently, because of its extreme invasiveness, all species of buckthorn have been banned from sales. It has also been placed on the Minnesota State Restricted Noxious Weed List. Although sales are prohibited, removal is not mandatory.

Two non-native species of Buckthorn shrubs thrive and spread in Edina’s wooded lots and other non-mowed areas throughout the City on both public and private property. Common Buckthorn (Rhamnus cathartica) and Glossy Buckthorn (Rhamnus frangula) grow abundantly in wooded lots, open meadows, along trails and streets, under specimen trees and other favorable sites. Buckthorn can grow on almost any site that is not continually mowed. Its seed is spread by birds after they eat the berries of the female plants.

Why is Buckthorn harmful?
Buckthorn displaces other more desirable plants; reduces beneficial and healthy biodiversity of flora and fauna; adds stress to trees through over-competition for nutrients, light and water; and grows in such thorny thickets that make passage difficult.

What is the City doing about Buckthorn?
The City encourages residents to remove buckthorn from their property. The City is also actively removing Buckthorn on specific properties and has formulated a comprehensive buckthorn management plan for parklands. City parklands have been assessed and prioritized to determine how best to direct resources.

How do I get rid of Buckthorn?
Buckthorn should not be cut without having a method of killing the stumps. If the stumps are not killed, they will re-sprout vigorously and be even more difficult to eradicate. Stumps can be chemically or mechanically neutralized or removed.

Uprooting
Buckthorn uproots quite easily. A mechanical tool called a weed wrench can pull out shrubs up to 2.5 inches in diameter and 10 to 15 feet tall. The City has a limited number of these tools available for residents to borrow at no charge. Some local hardware stores also rent this tool.

Chemical Treatment
Stumps can be chemically treated. The most common method is applying glyphosate at 25 percent concentration to fresh cut stumps. Same day application is the most effective. This should only be done from late summer through fall and as long as temperatures are above 32 degrees.

Glyphosate is an active ingredient in "Roundup" and other brand name chemicals. Glyphosate cannot be used near waterways. When treating stumps around water, "Rodeo" is recommended.

Grinding
Stumps can also be ground out with a stump chipper. They will not re-sprout.

What about the cover my buckthorn hedges provide?
Residents with buckthorn hedges who wish to remove them, but also need or desire the screening they provide, may want to formulate a gradual removal/replacement plan.

A potential restoration option in buckthorn infested areas is to replant native species. Native plants are naturally hardy and replanting may help reduce buckthorn regeneration.

The replanting of native plants is best suited for small areas where it is economically and physically feasible over the long-term. In the highly competitive environment of natural wooded lots, it is likely that a great quantity of these replants will not survive, unless continuous and future care is provided.

Also, any plan devised will most likely detract from a more natural, successive woodland composition. Plant selection and spacing in natural areas, when determined through natural selection, abiding by laws known and unknown, would more likely render a woodlot healthier and more aesthetically pleasing than would an artificially designed site.

Will buckthorn removal adversely affect the other plants in the area?
Residential property owners who wish to remove Buckthorn on property that contains natural, wooded areas of varying sizes should be aware of related concerns prior to formulating a removal plan.

Distinguishing between buckthorn and other species is important, especially when the goal is to preserve and protect all other plants during buckthorn removal. Not only will this help preserve the natural composition of the woods, but also provide shade that will help reduce regeneration of buckthorn plants.

Treat wooded lots as sensitive areas. Too many disturbances can cause stress that can lead to future declining or mortality among the plants that define your wooded lot. Avoid or minimize soil compaction in these areas. Soil compaction can adversely affect roots, which in turn adversely affects the visible vegetation. Overuse or abuse of chemicals is another concern. Over-reliance of chemicals could adversely affect the desired vegetation.

In most instances, removing the existing buckthorn shrubs is only the beginning. Buckthorn seeds stay viable for six to eight years. A sound management plan must be long term. But it should also be devised in such a way as to minimize disturbances.

Residents who wish to receive further information on this subject may contact the City Forester Tom Horwath at 952-826-0308.