Oak Tree Fungus?

Question

My grandfather lives right on the lake and all summer I was noticing this weird growth on the base of a large branch (what is left of one that must have come down in a storm at some point). It is a very pale yellow color, and almost seemed to look "dirty" as the weather dropped, but the last time I was up there, the "fungus" (if that's what it is) was still there. It's large, and doesn't resemble anything I've found on the internet. It just looks like someone sprayed a pale yellow foam/whipped cream for about 2 and half feet (in length) and most of the way around the entire circle of the branch.

Any ideas?

Answer 1

What you are seeing is a fungi called a "conk". It is feeding on the dead and now broken branch. Over time, as the fungi matures, it takes on a pale yellow appearance. Many conks form at the base of the tree trunk and some from above as you see on your grandfathers property. There are many types of conks in different shapes, textures, colors and sizes. Here is a link for you to see if any of these conks match the one you are talking about. Hope this helps.
http://www.fs.fed.us/r8/foresthealth/pubs/oakpests/p43-45.html

**Billy Ray**

Answer 2

Oak Wilt w/photo
http://www.treehelp.com/trees/oak/diseases-oak-wilt.asp
photo below
Tree With the Fungus at Bottom
http://www.flickr.com/photos/caretta71/1718813221/
Humongous Fungus!/photo
http://www.flickr.com/photos/85775297@N00/270435301/

Once a tree is infected, only rarely can the disease be reversed and the tree restored to health. Prevention, on the other hand, has a 90% chance of success. Two methods of prevention are recommended.
First, avoid pruning red oaks and live oaks during the period from mid-February through May.
http://www.northwoodhills.org/info/trees.html

It is my understanding that the oak trees here in the US are being lost due to wilt/fungus probably because they go untreated and it spreads.
Although the link above is for Texas it would apply all over except maybe for the pruning time.