The Morton Arboretum’s horticulturists are calling on homeowners and land managers in the Chicago region to remove the invasive plant species buckthorn from their property this fall and winter.
Once sold as an ornamental plant, buckthorn became popular for landscaping as a residential hedge or small tree. But in time, the plants form dense thickets and reproduce aggressively, blocking sunlight for other plants and disrupting native ecosystems. According to the Arboretum, buckthorn spread so aggressively that it can no longer be sold in Illinois under the Illinois Exotic Weed Act.
“Buckthorn causes long-lasting damage to the soil, making the soil inhospitable to other plant life,” said Julie Janoski, Plant Clinic manager at the Arboretum. “Getting buckthorn under control will require work on everyone’s part, including homeowners, municipalities, park districts, corporations, schools and other land stewards.”
The 2010 Tree Census reported that 28% of the Chicago region’s trees are buckthorn, with the majority on private lands. According to the Chicago Region Trees Initiative (CRTI), a coalition of more than 200 organizations working to build a healthier urban forest, environmental organizations in the Chicago region spend millions on eradicating buckthorn every year, but this effort still doesn’t address the majority of buckthorn that grows on private lands.
“Learning how to identify and successfully eradicate it on an individual level is the first step in diminishing this threat,” Janoski added.
Identification and Replacement
Buckthorn is a large shrub or small tree that is identified by glossy, oval leaves and dark-colored berries, which birds eat, spreading the seeds. The change in seasons presents an opportunity to easily find and replace the invaders, since leaves on buckthorn remain green longer than native species in the fall.
To help slow the spread, Janoski recommends removing buckthorn entirely and replacing it with more environmentally sound shrubs such as blackhaw viburnum, spicebush or hazelnut. “Cutting the plant to the ground will not kill it,” she cautioned. “Either the root system must be completely dug up or an herbicide is required to kill it.”
Those with questions about buckthorn can contact The Morton Arboretum’s Plant Clinic at plantclinic@mortonarb.org for advice. For online resources on identification, removal and replacement of the invasive species, visit ChicagoRTI.org/HealthyHedges.