True-
at the very least the ivy is not doing it any good...Competition for nutrients/water/available oxygen in the soil. Not to mention that heavy vines can effectively girdle the tree and hold moisture near the trunk promoting fungi growth. Cut the vines off the trunk and let them die off. Mechanically remove the parent stem from the ground or use some foliar herbicide ( but be careful) to kill the remaining ivy.
I'm not sure it will kill the tree, but it is unsightly. I cut the vines and immediately apply poison ivy killer concentrate to the bottom cut end with a brush. I have mostly poison ivy, which I leave alone to rot in the tree, but the virginia creeper and the other immitators I have i simply pull out of the tree, sometimes with the help of my tractor.
Good luck
Sounds like a nice tree, I would de-vine it. If you are close enough I can do it personally, it can get a little pricey but for the most part I can do it myself and leave the clean up for you.