By Katie Drewitz
University of Minnesota
October is a great time of year to spot and manage the buckthorn on your property. Buckthorn is a tall shrub or small tree that can reach 25 feet tall. It is commonly found in the understory of woodlands, fence lines, and forest edges. Buckthorn is easy to identify at this point in the season because its leaves maintain a dark green color after most trees and shrubs have changed color or the leaves have fallen off.
There are two species of buckthorn that are invasive in Minnesota, the common (Rhamnus cathartica) and the glossy (Fragula alnus). Both species are nonnative to Minnesota and were introduced in the early 1800s from Europe as a plant used for hedges. Landowners are encouraged to make efforts to control it on their property as it is on the Minnesota Restricted Noxious Weed List. Buckthorn is illegal to sell, transport without a permit, or intentionally plant in Minnesota. In addition, the common and glossy buckthorns are an over-wintering host site for soybean aphids and should be removed in fence lines and woodlands near soybean fields to reduce aphid populations.
Key identifying features include egg-shaped leaves with a pointed tip and stout thorns on the common buckthorn branches, while glossy buckthorn has oval-shaped leaves that are glossy and lacks thorns on its branches. Female plants produce berries that are dark purple to black and are in clusters with one-quarter inch berries. The berries are not edible to humans, but birds readily consume them and spread the seeds which contributes to their invasive nature.
Management includes hand-pulling seedlings or small trees. A tool called a weed wrench can also assist with removing plants up to 2 ½-inches in trunk diameter. Some local Soil and Water Conservation Districts or other offices may have them for check-out or rent. For larger trees, with a two-inch or larger diameter trunk, the plant should be cut down to the ground and the stump should be treated with chemical herbicide to prevent re-sprouting. Herbicides that can be used include brush or tree killing products containing triclopyr, glyphosate, or 2-4D. Always follow label instructions for herbicides. In some circumstances grazing by goats is also a viable control option.
For more information about buckthorn identification or control visit the Minnesota Department of Agriculture, Minnesota DNR or the University of Minnesota Extension websites. You can also contact your local Extension Educator. Residents in Fillmore and Houston counties can call (507) 765-3896 or (507) 725-5807 or email firstname.lastname@example.org.