Green Horizons

Volume 18, Number 3
Fall 2014

Treating ash trees for emerald ash borer

If you live in a county where the emerald ash borer (EAB) has been detected, insecticide treatments are a viable option to protect ash trees. But fall is not the best time. Insecticide treatments are most effective when applied in the spring. First, a homeowner should answer a couple questions.
  • Which ash trees are worth saving? Trees in poor health or growing in a poor location are not worth treating.
  • Is EAB nearby? Insecticide is not recommended if it’s not in your county or within 15 miles.
Trees with a trunk diameter smaller than 15 inches can be treated by the homeowner with a soil drench preparation of imidacloprid. Larger trees should be treated by a certified arborist. Applications can be made in early spring until March or mid-April and must follow label directions. Tree care professionals have additional options for types and timing of insecticide applications.

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