
Almost anything in poorly drained or compacted soil. General decline, thin canopy, early autumn colour, sometimes mushrooms at the base.
By the time the canopy shows it, the root system is already badly compromised. This is a stability question as much as a health one — a tree with rotten roots can look fine and still come over in a storm.
Central Indiana's heavy clay and high water table make this common, especially in newer subdivisions where topsoil was stripped.