Help! My wisteria plant looks as if it is dying.

[LXue]

Hi everyone. I’m new to this forum but I need help with my wisteria tree. It is approximately 15-20 years old. It has always grown quite prosperously in the past years, however recently I have noticed it has stopped growing. The leaves look dehydrated and are curling. The bark of the tree also have creamy coloured white fungus patches. A lot of the very small branches at the top also have coiled and are extremely dry and white inside. Could anyone give me advice please. Thank you very much.