A dying ash tree typically shows a range of distinct symptoms, most notably a sparse crown and changes in its bark, often due to infestation by the invasive emerald ash borer (EAB).
Key Visual Indicators of Ash Tree Decline
Identifying a dying ash tree involves observing several key visual cues, which often begin in the upper canopy and progress downwards. These signs indicate the tree is under severe stress, frequently from pests like the emerald ash borer.
Canopy and Foliage Changes
- Sparse Crown: One of the clearest indicators of a dying ash tree is a thin, sparse crown. Instead of thick, dense foliage, the canopy will appear much thinner, with fewer leaves than usual. You may observe few or no new leaves growing, which is a significant sign of decline, often linked to an emerald ash borer infestation.
- Canopy Dieback: Branches in the upper crown will start to die, losing leaves, becoming brittle, and breaking easily. This dieback often begins at the top and works its way down.
- Yellowing or Browning Leaves: Leaves may turn yellow or brown prematurely, especially during summer months, well before autumn.
- Premature Leaf Drop: Leaves may fall off the tree earlier in the season than is typical for ash trees.
Bark and Trunk Symptoms
- Vertical Cracks or Splits: As the tree attempts to cope with stress or pest infestation, the bark on the trunk can develop vertical cracks or splits.
- Flaking Bark: Bark may begin to flake or peel off, revealing the wood underneath. This is often associated with increased woodpecker activity.
- D-shaped Exit Holes: A tell-tale sign of emerald ash borers is the presence of small, D-shaped holes in the bark, typically about 1/8 inch (3-4 mm) wide. These are made by adult beetles emerging from the tree.
- S-shaped Galleries: If you peel back the bark on a dying ash tree, you might find distinctive S-shaped feeding galleries carved into the wood just beneath the surface. These are created by the emerald ash borer larvae.
Unusual Growth and Activity
- Epicormic Shoots (Water Sprouts): In response to severe stress, the tree may produce clusters of new shoots or branches directly from the trunk or larger branches, often near the base or where the canopy is thinning. These are sometimes called "suckers" or "water sprouts."
- Increased Woodpecker Activity: Dying ash trees often attract woodpeckers. These birds feed on EAB larvae under the bark, leading to noticeable bark flaking and lighter-colored patches on the trunk, sometimes referred to as "blonding."
- Basal Sprouts: Similar to epicormic shoots, new sprouts may emerge from the base of the tree or from the root collar.
Summary of Dying Ash Tree Signs
Here's a quick overview of the primary indicators:
| Sign | Description | Common Cause |
|---|---|---|
| Sparse Crown | Thin foliage; few to no new leaves growing. | Emerald Ash Borer, overall decline |
| Canopy Dieback | Branches in upper crown lose leaves, become brittle, and break easily. | Emerald Ash Borer, disease |
| Bark Changes | Vertical splits, D-shaped exit holes, or peeling bark. | Emerald Ash Borer activity |
| Epicormic Shoots | Clusters of new shoots growing from the trunk or main branches. | Tree attempting to survive stress |
| Woodpecker Damage | Increased activity, often leading to noticeable bark flaking ("blonding"). | Woodpeckers feeding on EAB larvae under bark |
Why Ash Trees Die: The Emerald Ash Borer Threat
The primary reason for the widespread death of ash trees in North America is the emerald ash borer (EAB), an invasive beetle. Its larvae feed on the inner bark, disrupting the tree's ability to transport water and nutrients, ultimately leading to its decline and death.
To learn more about the emerald ash borer and its impact, consult resources from reputable organizations like the USDA Animal and Plant Health Inspection Service.
When to Act: Seeking Professional Help
If your ash tree exhibits these signs, it is highly recommended to consult a certified arborist or tree care professional. They can accurately diagnose the problem, assess the tree's health, and recommend appropriate actions, which may include treatment or removal. Finding a local certified arborist can be done through organizations like the International Society of Arboriculture.
