Buckthorn was introduced to North America in the 1800s and was considered a desirable hedging plant. It has since become extremely invasive and difficult to eradicate. Forming dense masses on the forest floor, it easily crowds out native plants, shrubs, and saplings that are important to our natural ecosystem. There are effective ways to remove and kill buckthorns, however, and to help native plants return and become established.
Now is a good time to remove Buckthorn. Native plant’s leaves will begin to turn color and drop their leaves, but buckthorn remains green for quite some time, making it easier to identify. Plants are also responding to shorter days and are taking up nutrients more quickly, so they’ll also take up herbicide more quickly.
There are three basic steps to successful Buckthorn removal – cut, treat, and replace. The way in which each of these steps is performed, however, is critical to effective removal.
Cut stumps short so they will be less likely to re-sprout after treatment - about 2” above the ground. Cut small shoots with a hand pruner 2” above the ground as well.
Although it’s often preferred to use little or no chemicals whenever possible, Buckthorn cannot be effectively controlled without chemical applications and would require constant cutting and hand-pulling that would never fully allow for natives and other plants to become established.
For effective control and killing of buckthorn, Tonkadale recommend Bonide KleenUp
with the active ingredient glyphosate, or Bonide Stump-Out
with the active ingredient triclopyr.
Follow label directions for dilution and apply the chosen chemical to the basal bark of the stump. This is the outer ring of the cut surface of the stump. Covering the whole surface of the stump or pouring chemical into drilled holes will not kill the stump more effectively and will only cause unnecessary over-exposure of chemical to you and the environment.
Gradual removal is the best option if Buckthorn is a large presence in the landscape. Undercutting an entire area quickly changes the landscape and can allow for other invasive species growth (especially a problem if garlic mustard is present!) and can cause erosion.
Buckthorn's greatest threat has been to native plant life. Sometimes plants will come back when their competition has been removed, so be on the lookout for little pockets of native plants. If there are spaces that need to be filled, consider planting native plants that would have once been naturally occurring.
Native plants that will naturalize and provide beauty include Virginia bluebells, bloodroot, and Wild Ginger.
There are also several wonderful native shrubs and trees that can aid in restoring the natural ecosystem and offer the shade and structure that Buckthorn once provided. Some to consider: Witch hazel, pagoda dogwood, ironwood (difficult to find, but worth it), sugar maple, or black cherry.
For more information visit the University of Minnesota Extension website: http://www.extension.umn.edu/
or the Minnesota Dept. of Natural Resources website: http://www.dnr.state.mn.us/index.html
This DNR publication is especially helpful: http://files.dnr.state.mn.us/natural_resources/invasives/terrestrialplants/woodyplants/buckthorn_what_you_should_know.pdf