Welcome to permies, W Scott!
I have 3 suggestions for you: 1. Prune and strip the leaves off as you do as the leaves make great
mulch.
2. Prune harder and more often.
3. Prune right back to the main stem and let it regrow from there.
Sorry I can't be more helpful! I have one that was climbing our back deck when we bought the house and I had no idea just how severely the previous owners must have been pruning it. Do watch out for new suckers as I find the plant pretty sneaky and it's much easier to kill small babies. I don't really want to kill it - the flowers are lovely and attract
bees. I've never seen it germinate any of the few seeds it makes, and it really will tolerate my son "pruning" it with a machete and simply put out new growth. Most of the leaves I can get for mulching veggie beds are from raking leaves that have fallen on our
lawn which is a
polyculture with seed heads I'd rather not introduce to my beds. But I can prune the Wisteria at *any* time of the year, strip the leaves and there won't be weed seeds. An attached branch that touches the ground will root, but I've not had chopped branches root, although I usually have chopped them into 3 foot or smaller lengths. If you're willing to burn a few fossil fuels, I'd consider using a chipper/shredder to deal with the first major prune.