Yes, they’re huge, some six inches diameter, and snaking their way up the trees, many over forty feet long. I’m talking of Oriental Bittersweet Vines. (What were you thinking? Ha! Ha!)
They’ve got a great death grip on the trees which are dying slowly. This invader from Asia will grow up to the canopy of the forest and gradually overwhelm the trees. Their weight, along with winds and snow, will pull the tree to the ground in many instances.
In The Oxbow Woods, I eventually came across the Mother of All Vines, some six to eight inches in diameter, growing in numerous directions right in the midst of a stand of very tall beech trees, just like those in Hart’s Woods. From their sheer size, one would estimate the vines being at least seventy years old.
The vines have spread over the ground to encroach on several trees and is well evident in the canopy. I don’t doubt that these tree’s days would have been numbered if we hadn’t discovered this vine. It’s also probably the source of the infestation throughout the woods.
We’ve already cut through some vines and you’ll see the evidence from the dead leaves hanging from the trees. Don’t be tempted to pull on a hanging vine though. It could be just enough pressure to pull the tree over and cause you harm. Once cut, it is recommended to simply let the hanging vine dry up and it will eventually fall away from the tree’s branches in a couple of years. There are no biological remedies for the elimination of Oriental Bittersweet vines, so it’s up to us to control it.
American Bittersweet V Oriental Bittersweet.
Unfortunately, these two varieties sometimes hybridize and it can be difficult to distinguish between the two species. In the fall, the American native has berries only on the end of the stem, as shown below, and I’m not sure what happens when they hybridize, so for the time being, due to the severe infestation here, we’ll consider cutting all the vines.
Among this stand I noticed one tree had a different vine, Poison Ivy. It’s a whopper too, with a trunk diameter of about two inches. No doubt this is the original seed source of all the poison Ivy throughout the Oxbow. The Boy Scouts have removed most of it, but one still needs to be on the lookout for this miserable plant.
Notice how the trunk of the vine has little hairs growing from it and the leaves are, of course, the tell tale three (if there’s three, let it be). Letting it be is not going to happen. It’s got to go. We’ll probably gear up with gloves etc, and gently hand saw through the trunks.
Regular, weekly mowing will control Oriental bittersweet, but less frequent mowing may result in suckers growing from the roots.
Here are the berries and leaves of Oriental Bittersweet.
Over this summer, several very large trees in The Oxbow Woods have been felled by Bittersweet Vines. This is the latest victim.
Some useful reading –
Minnesota Dept of Agriculture ruling All above and below ground parts of the plant must be destroyed. Additionally, no transportation, propagation, or sale of these plants is allowed. Failure to comply may result in enforcement action by the county or local municipality.