All ash trees have opposite, compound leaves, and opposite branches and twigs. The bark of ash is ashy gray or gray brown, furrowed, with narrow interconnecting ridges connecting diamond-shaped spaces.
A healthy ash will be fully leafed out, have a good root flair, good branch unions, good growth vigor, and few if any signs of EAB.
Iowa State University Extension
Iowa DNR, USDA Forest Service, USDA APHIS, and ISU Extension
ISA Trees are Good
Emerald Ash Borer University