Poison Ivy is one of those weeds that can run but it can’t hide in the fall. Poison Ivy is just too colorful with orange, yellow and red pigments in its foliage all on the same plant. Its aerial roots along the stem grip the bark of trees and send it skyward putting it in plain sight, especially in fall when it becomes a colorful character. Take me to your “weeder”……fall is a good time for control.
Applied herbicides are translocated effectively into the root system as the plant shuts down for winter like the trees. Carefully follow the main stem down to the base and make a clean cut. Wearing protective clothing like rubber gloves simply brush some brush killer straight onto the fresh cut at the base. The vine cut off from the root system will die on the tree. I do not recommend trying to pull it off the tree. “Weeding” by example. The stump in the ground will absorb the herbicide and begin its work on killing the roots.