Ash species attacked by emerald ash borer include green ash (Fraxinus pennsylvanica), white ash (F. americana), black ash (F. nigra), and blue ash (F. quadrangulata), as well as horticultural cultivars of these species. Green and white ash are the most commonly found ash species in the Midwest with blue ash being rare.

While other woody plants, such as mountain ash and prickly ash, have “ash” in their name, they are not true ash (Fraxinus) species.

Only true ash are susceptible to attack by emerald ash borer.

How to properly identify ash trees

Branch and bud arrangement

Picture of Ash Tree Buds Picture of Opposite Branching in Ash Trees

Branches and buds are directly across from each other and not staggered.

When looking for opposite branching in trees, please consider that buds or limbs may die; hence not every single branch will have an opposite mate.

Leaves

White Ash Tree Leaf

True ash leaves are compound and composed of 5-11 leaflets. Leaflet margins may be smooth or toothed.

The only other oppositely branched tree with compound leaves is boxelder (acer negundo), which almost always has three to five leaflets.

Bark

Picture of Diamond Pattern in Ash Tree Bark

On mature ash trees (right), the bark is tight with a distinct pattern of diamond-shaped ridges.

On young trees, bark is relatively smooth.

Seeds

When present on ash trees, seeds are oar-shaped samaras. They usually occur in clusters and typically hang on the tree until late fall, early winter.