Q.Why Is My Wisteria Shedding Its Leaves
My wisteria flowered well in the spring and now suddenly it is shedding all its leaves. They feel very dry and papery and some have gone yellowish. Yesterday I left the hose pipe on it for three hours, but today there has been no change and it looks worse again. The plant is about 15 years old and has never been any trouble before.

Certified GKH Gardening Expert
It may be a fungus, or it could be an issue with the root.
Treat the plant with a fungicide. And then check the roots. These plants can sometimes get root galls, which can affect their ability to take up water. There may also be a pest attacking the roots.