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.
Pear tree leaves, fruit, twigs and branches can become infected by fungus. Some of the symptoms of fungal infection are black spots on leaves or stems, early leaf drop or curling and blackening of the leaves. Flyspeck, sooty blotch, fabraea leaf spot and pear scab are all fungal infections commonly affecting pear trees.