
Oak wilt decline is fast and distinctive: leaves bronze from the tip and outer margin inward, then drop while still partly green, and a full crown can go bare in a matter of weeks. Slow, patchy thinning spread over several years is a completely different problem — usually compaction or root stress, and often treatable — so the speed of leaf loss is the diagnostic that separates stressed from dying.
Despite smooth, unlobed, laurel-like leaves that look nothing like an oak, this is a red-oak-group species — the single most important fact about the tree. Red group means full oak wilt susceptibility and death within a single season, and homeowners (and occasionally crews) misread it as a non-oak and cut it in June.