Oak Leaf Scorch is NOT Leaf Scorch; former is bacterial, latter fungal. YOU CAN TREAT (see research paper under "more" tab). Bacteria will kill a tree in a season or a couple years. IF you see dead leaves or branches randomly in the tree during the spring or summer call an Arborist asap! Once the tree has it, it can be treated ($190 - $275/yr). Preventative treatments provide your oaks three years of protection from a variety of pests and are the best solution.
Links to various oak-killing diseases being found or increasing in severity in the southeast and eastern US:
Other Oak Diseases
Unlike Oak Leaf Scorch, Oak Wilt is caused by a fungus, Bretziella fagacearum (was Ceratocystis fagaceae). I've sampled 15 tress randomly in the Knoxville area and another 3 outside of Knoxville and had 12 of those tested with molecular techniques - the only method to be certain whether bacterial or fungal infected; I'm happy to report none of them had OLS. Five came back positive (not through molecular analysis but visual estimation, as anthracnose infected. The oak wilt fungus is coming in on rhododendrons, one of the nearly 200 plants that can "host" this fungus. Identifying and differentiating the three diseases can only be done by either growing the pathogen from leaf material or through molecular analysis. My instincts are to not trust visual diagnoses. All three pathogens can kill a tree under the right circumstances and unfortunately, hot dry weather and hot weather can favor death by anyone of them. So - please review the links provided here and water your trees when the temps are >85 with more than 6 days w/o rain.
Emerald Ash Borer
Hear recently on a local news radio show someone from city management reporting that once the trees have been 'hit' by this beautiful beetle, they are essentiall dead. NOT TRUE!!! You can treat them to stop the insect with a systemic treatment. If more than 2/3 of the canopy is gone - yes it is more than likely the tree cannot be saved. But 2/3 of the canopy remaining or more and it is worth treating. Treatments last 1 to 3 years. I provide a DIY protocol for this because we need to protect as many of these trees as possible. Losing our ash trees will significantly impact forest especially lowland and wetland habitats! The ones we keep alive, in our cities will provide the seeds for the future - literally! There's research being done on a possible predator of the beetle. So, protecting all we can until other alternative arise is a smart green choice.