Dying willow oak?

[David Kirkpatrick]

I have a willow oak which I transplanted to my front yard four years ago. 
 It seemed to establish well and grew well until recently - to about 12 
feet tall with a trunk about 3 - 4" in diameter.

However in early July all of the leaves turned orange, then brown and 
although they are on the tree now it looks pretty dead.  The branches are 
brittle but seem to have some sap in them.  I am in NC and we had lots of 
rain in June, and the soil is mostly clay but the tree is on a slight 
slope.

When I looked around the base of the tree - I found a band of white 
fungus around the trunk and white fungus on the roots and wood and yard 
waste mulch around the trunk.  I took samples to the Cooperative Ext. 
office and they sent them to NC State but the report came back "diagnosis 
unknown - the fungus present is one that grow on dead wood" and thus not 
root rot as I had worried.

I mulched the tree heavily last fall with yard waste compost from the 
city and did not pull back the mulch from the trunk as I should have.  

Anyhow - I would like to save the tree, but don't have much hope.  If it 
dies and I replant, I would not want to have this happen again.  Any 
ideas?  Also - are there other newsgroups dealing more with trees and 
tree diseases?  Thanks for any assistance.