CAN I SAVE MY TREE FROM A DEADLY FUNGUS?

Grateful Deadhead

Hi Everyone, 

The tree in question is a large, male goat willow. There is a brown powdery substance at the base of one side of the tree, while in a short space of time the tree canopy is either dead or at least not producing foliage. One branch seem to die a year or two back and only very recently (last 2-3 months) another two or three branches have been noticed to be barren. So currently, about 45% of the canopy is bare! it such a beautiful tree. Please could anyone give any advice which could help save our tree? 

The side of the canopy which appears to have suffered is the same side of the trunk where the brown powdery fungus has been found. 

I have photos but I cant upload due to technical problems at the moment.

Thanks

Grateful Deadhead

Fire

It's often said here that it is probably not the fungus killing the tree, but the fungus growing on a tree that is already dying. Photos would help an opinion, for sure.