Chop it at the base of the tree. Get the concentrated ivy killer. Pour whole bottle into two gallon sprayer. Spray the **** out of it. May have to do it multiple times but it will kill it. I had a bunch in my yard and its been gone for 4 years now
I had a mess of stuff growing when we bought our house here, and as stated above I cut them at the bottom, but on the planted stuff I left about 2 feet, and sprayed them with this stuff I call "agent orange" The real name of it is Ortho Poison Ivy and Tough Brush Clear Concentrate. I used this stuff at our old home because I'm really allergic to poison ivy, and this stuff kills sit and everything else you spray it on. For some reason it's not sold around here, but you can get it from Amazon, or HD and Lowes, by mail, but they don't stock it in stores. As soon as you spray it on anything, the plants start to drop, and once it's dried you can release the dog and it won't bother them. (if you have one) I'm on my 2nd year without having any growth where I sprayed it, I had it so bad it was choking the trees and I pulled down almost all of it in the trees and burned the vines.
I cut a 12” section at the base when I had it in about 8 trees. Be gentle removing those sections so you don’t damage the bark. Selectively sprayed Roundup with a little dish soap to help it stick, for the remaining ivy on the ground. Careful that you don’t overdo the herbicide and damage the trees.