It has already moved through Indiana and killed the overwhelming majority of untreated ash. An untreated ash here is on a clock, not at risk. In Carmel, carmel Urban Forestry publishes an approved species list (last revised 3/28/2024) whose "Undesirable Trees" section reads like a field guide to what fills older Hamilton County streets: silver maple (shallow roots, weak wood), Callery pear, pin oak, red maple and all Fraxinus for emerald ash borer. Approved large street trees run to swamp white oak, bur oak, chinkapin oak, hackberry, male-only ginkgo, thornless honeylocust, Kentucky coffeetree, baldcypress and London planetree; note Callery pear is discouraged locally but is not yet banned in Indiana — 312 IAC 18-3-25 currently lists 44 species without it. Treatable while the canopy is still mostly intact.
Carmel's canopy and what's at risk
Carmel Urban Forestry publishes an approved species list (last revised 3/28/2024) whose "Undesirable Trees" section reads like a field guide to what fills older Hamilton County streets: silver maple (shallow roots, weak wood), Callery pear, pin oak, red maple and all Fraxinus for emerald ash borer. Approved large street trees run to swamp white oak, bur oak, chinkapin oak, hackberry, male-only ginkgo, thornless honeylocust, Kentucky coffeetree, baldcypress and London planetree; note Callery pear is discouraged locally but is not yet banned in Indiana — 312 IAC 18-3-25 currently lists 44 species without it.
What to look for
Thinning from the top down, D-shaped exit holes about an eighth of an inch across, sprouts low on the trunk, and pale flecking where woodpeckers have stripped bark to get at larvae.
Whether the tree can be saved
Treatable while the canopy is still mostly intact. Once roughly a third of it is gone, treatment stops being worth the money and the tree becomes a removal — and a dead ash goes brittle unusually fast, which makes it both more dangerous and more expensive the longer it stands.
Timing in Hamilton County
Trunk injection in spring or early summer, repeated every one to two years for the life of the tree. It is a permanent commitment, not a cure.