Q. Autumn Purple Ash tree (Fraxinus americana 'Autumn Purple') leaf drop and slow regrowth
This past winter was so devastating that it is probable that not only was the fungus killed, but some of the branches of the tree might have been damaged as well. It is possible that the tree needs to be pruned, and the bare branches removed in order to stimulate growth. Shaping the tree while pruning might be in order too. Check with a registered arborist in your area to see exactly what state of health the tree is in, whether the fungus has returned or whether this is evidence of the winter's ravage , and you will get the advice you need.