1 Iritis is uncommon, but can be due to trauma, infections, or autoimmune conditions. Symptoms include pain, red eye, and often, decreased vision.  Optic neuritis. The nerve travelling from the back of the eyeball into the brain can become inflamed.
Oak root fungus, or white rot, is a widespread disease that becomes visible just beneath the bark and on roots. What looks like layers of light brown to tan mushrooms form in clusters at the base of the trees.
When mushrooms or conks, also called a bract or shelf, grow on tree bark, it is usually a sign that the tree is infected with a rot-inducing pathogen. While not all mushrooms are harmful to trees, many are. They cause heart decay, which causes healthy trees to begin to rot at the heart of the trunk.