I’m posting this with the hope that park managers and other government officials will start taking this invasive plant seriously and do something about it NOW. (Originally written for the Greater Mohican Audubon Newsletter.)
There’s nothing sweet about Oriental bittersweet. Unless it’s watching the leaves wither up after cutting the vines or treating it with herbicide.
But don’t be lulled by temporary successes in controlling Oriental bittersweet (Celastrus orbiculatus). This aggressive invasive is tenacious. And it seems to have more friends than enemies.
In a 2018 article on Buckeye Yard & Garden onLine, Amy Stone refers to Oriental bittersweet as the “kudzu of the north.”
“Oriental bittersweet is invasive vine that is native to China, Japan and Korea,” Stone wrote in her article. “It was introduced to the United States as an ornamental plant around 1860. This deciduous, woody, twining vine can climb on trees, shrubs and anything else in its way.”
It was also introduced for erosion control, similar that notorious invasive Japanese knotweed (Fallopia japonica).
Yes, like so many other invasive plants, careless or clueless entrepreneurs introduced Oriental bittersweet to the U.S. To make matters worse, Oriental bittersweet is still sold here and prized for its colorful berries, which are used as decorations.
It’s easy to see where that could go awry. It’s bad enough that birds are spreading the seeds far and wide. Add to that well-meaning consumers spreading a little holiday joy — along with a nasty invasive vegetation.
Oriental bittersweet should not be confused with native American bittersweet (Celastrus scandens). But it can be. There are subtle differences between them. However, Stone advises that, “To add to the possible confusion, the two different species in the same genus (Celastrus) are crossing and producing plants that sometimes have characteristics of both the native and non-native species.”
What does it look like?
The University of Maryland Extension provides this description:
Growth habit: climbing, deciduous vine; leaves rounded to obovate, alternate, simple with bluntly toothed margins.
Reproduction: seed; flowers are inconspicuous followed by green to yellow fruits that burst open to display orange-red seeds persisting into fall after leaf drop.
According to the U.S. Department of Agriculture, it prefers upland meadows, thickets, young forests, and beaches.
What’s the harm?
Oriental bittersweet quickly takes over the landscape. Its deciduous woody vines create thickets, encircling tree trunks like boa constrictors, climbing upwards and choking the life out of them. The weight of the vines can pull down large trees. For that reason, those working to control this horrible invasive are warned never to tug at vines to remove them from trees or branches. It also shades out understory plants.
How could things possibly get worse? Oriental bittersweet also spreads underground; it reproduces by putting out root suckers.
To see the devastation up close, visit Charles Mill Lake Park on the Ashland and Richland county border. Oriental bittersweet is everywhere, even on the islands. In some places, the infestation is so bad that bittersweet vines are actually choking themselves.
What can be done?
In Ohio, public officials in general have yet to demonstrate any sense of urgency when it comes to controlling Oriental bittersweet and other invasive plants. On your own property, you can control it by constant cutting or mowing, pulling small vines or cutting large ones and treating the stumps with strong herbicide such as Triclopyr. (Glyphosate just won’t cut it.)
Treatment can be done any time of year, but stump treating is best done in late summer.
For a good video on Oriental bittersweet control log on to https://www.youtube.com/watch?v=7wmZ1Zuho1c.
This video also serves as a great resource for identifying Oriental bittersweet.
Here’s a less-widely accepted method to control Oriental bittersweet. Save lengths of vines as you cut them. Keep them handy in case you find someone selling Oriental bittersweet — and strangle them.