Answer: Things sound suspicious with the one affected tree. Black leaves on a tree are usually attributed to the weather. A late frost can burn the leaves, turning them black. Frost can also affect the leaf buds and cause the unfurling leaves to be distorted. If this is the case, simply rake up the fallen leaves. Your oak should replace the lost leaves.
While you're raking, take time to inspect a few of the fallen leaves. Look for signs of insects or disease. The first symptom of a fungal disease called oak wilt shows up as browning leaves, starting at the outer edge and working its way towards the stem of the leaf. If you find black spots on the affected leaves which indicates fungal spores you might want to place a few of the leaves in a sealable plastic bag and take them to your local cooperative extension or Master Gardener clinic for positive diagnosis.
Let's hope the problem is weather related and not a disease!
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