An interesting discovery.
The area of infestation has a mass of vines coming out of one particular part of the ground by my neighbors
apple trees/barn. We dug a little ways down only to find a ton of roofing slate laid flat in layers of the dirt.
The vine had shot roots through the slate taking up an available space and nothing could compete with it.
We are currently excavating the slate shingle by hand and ripping up a mass of
root material. Not pretty or fun but hopefully will have a big impact.