Question
Our wisteria has been healthy and flowered for the past 10 years. This year it flowered and in last 2 weeks all the leaves have just died. (Another wisteria is still healthy in another part of the garden)

There is no evidence of fungus on the leaves or branches.

I have made cuts which shows that branches are milky color and not green as per another Q&A on this site.

It is planted near a pyracantha which has a mildew on it- this has been there for years.

Any thoughts on what to do to save the Wisteria

Answer
The plant is probably still alive and I would leave it alone until next spring and see what happens then.  The sudden defoliation is of concern, but I know of no reason why it has done this.  It may be the drastic change in weather patterns we have seen this year.  Good Luck.