Oh, BTW, glyphosate just pisses it off. We do have one herbicide that is effective on it (I can't remember the name of the top of my head), which helps with the fence rows, but is rather hard to spray way up in trees.
I have some old poison ivy vines as thick as my wrist going up some of my trees. I can't spray the leaves so I have to cut the stems. However, my optimal herbicide for foliar spraying also works well on the cut stems.
I did read up on Asian Bittersweet. Triclopyr is one of the preferred herbicides, and the product labels says it can be applied directly to cut stems/trunks. (If you are having good success with a different herbicide, you might check the label and see if it also works on cut stems.)
If you have some nice trees you need to save, perhaps you could try cutting and treating some stems at ground level? If you don't get a 100% kill rate, you might try experimenting with determining the optimum time of year for treatments. For my trees that sucker from the roots (like your Bittersweet), my best kill rate is to treat in the fall when the sap is moving back down to the roots.
