Hi, we have a large mushroom/fungus growing on the trunk of an oak tree about...

Asked July 4, 2014, 3:48 PM EDT

Hi, we have a large mushroom/fungus growing on the trunk of an oak tree about 4-5 ft off the ground. Some of the leaves have yellowish spots on them. The tree is not losing any leaves and seems healthy. The tree is about 30-40 ft tall, the trunk is 5 ft in diameter at the base of the trunk. Can you identify this fungus and should we be worried as the tree is an important shade tree in our yard? Or is it edible and can I cut it up and add it to some shish kabobs?

Hennepin County Minnesota

1 Response

We aren't qualified to identify the fungus, but we do know that such growths indicate that portions of the tree are decaying. (The organism in the photo is known generically as a shelf or bracket fungus.)

You should be concerned. However, the extent of the decay, degree of hazard and its likely effect on the tree's longevity can best be assessed onsite by a forester or certified arborist.

Some shelf fungi are edible, but others may be toxic or woody and generally unpalatable.

Learn more here:

Wood Decay Fungi on Living Trees
http://www.umass.edu/urbantree/factsheets/25wooddecayfungi.html