Q.possible disease of bloom moon wisteria 3 years old
I live in Fargo, N.D. I bought a blue moon wisteria plant 3 years ago. The plant was doing well last year growing and coming over a pergola . 2 weeks ago the plant was growing leaves, and today I notice the leaves are small , dark green and limp. What is wrong? Can it be treated before I lose the entire plant ? Please advise . My email is k.sherman52@hotmail.com. Thank you, Kathy

It is difficult to say from your description.
These links may help you pinpoint the issue.
https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-no-leaves.htm
https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-with-yellow-leaves.htm
https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-diseases.htm