When should I treat for emerald ash borer? (Lawrence, Indiana)

When should I treat for emerald ash borer?

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 Lawrence, about 1,700 acres of the former Fort Benjamin Harrison went to Indiana DNR as Fort Harrison State Park (sources differ on the exact acreage transferred), described as one of central Indiana's largest hardwood forests — oak, hickory, beech, walnut and maple, with a one-mile Tree ID Trail off Millennium Grove. Outside the park the picture inverts: a 2026 urban forestry assessment by IU McKinney Climate Fellow Taylor Stout found Lawrence has no tree inventory at all, that most surveyed trees are in good condition but overdue for pruning and re-mulching, and that southern Lawrence around Pendleton Pike and Post Road is the hottest and least-treed area. Treatable while the canopy is still mostly intact.

Lawrence's canopy and what's at risk

About 1,700 acres of the former Fort Benjamin Harrison went to Indiana DNR as Fort Harrison State Park (sources differ on the exact acreage transferred), described as one of central Indiana's largest hardwood forests — oak, hickory, beech, walnut and maple, with a one-mile Tree ID Trail off Millennium Grove. Outside the park the picture inverts: a 2026 urban forestry assessment by IU McKinney Climate Fellow Taylor Stout found Lawrence has no tree inventory at all, that most surveyed trees are in good condition but overdue for pruning and re-mulching, and that southern Lawrence around Pendleton Pike and Post Road is the hottest and least-treed area.

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 Marion 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.

When should I treat for emerald ash borer?

Lawrence's canopy and what's at risk

What to look for

Whether the tree can be saved

Timing in Marion County

Crews near Lawrence

R&C Tree

DC Tree Services LLC

Williams Tree Service LLC

Hoosier Elite Tree Services

Eating Tree Service

PR Tree Service

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