Bittersweet
Celastrus orbiculatus
Why is it a problem?
Introduced from East Asia in the late 1800s, bittersweet has become a significant threat in Northern Michigan. Several varieties of this invasive vine are particularly problematic, as they outcompete native species and deplete food sources for wildlife, including birds. Bittersweet can climb up to 60 feet, encircling trees and shrubs and disrupting their access to water and nutrients. Its dense growth also adds considerable weight to tree canopies, further straining the trees.
How to identify it?
Bittersweet does have a native look-alike called American bittersweet, especially when the two hybridize. Invasive bittersweet has orange/red berries present in the fall and are green in the summer seasons. These berries form along each leaf axil which is a key feature when distinguishing invasive vs native bittersweet. Invasive bittersweet leaves are alternate and finely toothed, appearing oblong and sometimes round.
How to manage it?
Mechanical controls for bittersweet are not an effective form of eradication. Herbicide treatments have generally been the most effective form of treatment. You can check out the DNR recommendations for treatments. (Link)
