My tree is dropping leaves in July like it's already fall — what should I do?

Leaves yellowing, browning, or spotting and falling well ahead of season — anywhere from June through August in central Indiana. The pattern is the diagnosis. Dark spots or blotches along the veins, dropping from the lower and inner crown first, points to a foliar fungus. Leaves turning uniformly dull, hanging limp, then dropping across the whole tree points to a water or root problem. Wilting and browning confined to one branch or one side, with dark streaking under the bark when you cut a wilted twig, is a different and more serious picture. Scattered interior leaves yellowing and dropping in a hot dry August while the outer crown holds is often just the tree shedding what it cannot support, which is normal. Leaf drop is a tree's cheapest response to almost any stress, because leaves are what cost it water. So the symptom alone means only that something is wrong, and the useful question is what — the range runs from harmless to terminal. Foliar diseases like anthracnose on sycamore, ash, and maple, or apple scab on crabapple, strip a tree, look alarming, and generally do not kill it. Drought, girdling roots, a buried root collar, and construction injury drop leaves for a reason that will still be present next year. Vascular wilts — Verticillium in maple and redbud, oak wilt in the red oak group — drop leaves because the plumbing is being blocked, and those are serious.