Hi Brian,

Great question. Sorry to hear you're dealing with oriental bittersweet (Celastrus orbiculatus). It's a tenacious invasive that can cause some real damage and is a real threat to Vermont ecology.  

You're not the first to ask this, so I'll give you basic first steps and cherry pick info from a few resources listed below for your later review. 

First and easiest step is to cut all vines at ground level and eye-height. Don't worry about getting the vines out of the trees as that might cause further damage. They will dry and rot in due course.

Now keeping them from returning is the hard part.  Per UPenn Extension (linked below): "Often, the most feasible approach is to cut the existing stems, forcing the roots and stumps to send up new shoots, and then treat the regrowth with foliar-applied herbicides." 

There is extensive information on timing and process in the UPenn article if that's the route you choose. If you're un-inclined to use chemical treatments, the UPenn articles says: "Cutting alone is only effective at controlling the vines when resprouts are repeatedly cut until the root system is exhausted. This will take multiple cuttings annually over several growing seasons. Mowing has been shown to encourage root sprouting and may not control the plant even when repeated periodically. Missing even one cutting during this regimen is likely to give the vine a chance to recover and reestablish."

And the last bit of sage advice the article gives is: "As described in prescriptions to address other invasive plant invasions, the best approach to combat this habit is to "save the best." In other words, plan to work from the least to the most invaded areas or in areas where there is desirable native vegetation. This will maximize uninvaded acreage, which is not only of higher ecological value but also creates a much greater sense of accomplishment. Because Oriental bittersweet seeds are dispersed by birds, new invasions can and will occur. Spot removal of isolated individuals must be a part of any long-term invasive plant control program."

I wish I had an easier plan for you but I tip my hat to you for taking it on!  I'm in the midst of a multi-year buckthorn battle in my backyard. Not fun but it's for the betterment of the whole forest! Good luck and happy new year! 

Thanks for reaching out the UVM Extension Master Gardener Helpline. 

Resources: 

• VT Invasives
• UPenn Extension
• UMaine Extension