Tree Care

Identifying Emerald Ash Borer Signs

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Emerald Ash Borer (EAB), an invasive beetle native to Asia, has wreaked havoc on ash trees across North America since its discovery in 2002. With its devastating impact, early detection is crucial for managing and protecting your ash trees. In this article, we will explore the key signs and symptoms that indicate the presence of EAB. By recognizing these indicators, you can take proactive steps to save your valuable ash trees from this destructive pest.


"S" Shaped Galleries: A Telltale Sign

One of the most distinctive signs of an Emerald Ash Borer infestation is the formation of "S" shaped galleries beneath the bark. The EAB larvae create these galleries as they feed on the tree's inner layer, the cambium. Over time, the tunnels widen, forming these winding, serpentine patterns.


To check for "S" shaped galleries, carefully peel a piece of the tree's bark back. However, remember that this should be done cautiously, as excessive damage to the tree can weaken it further. If you observe these galleries, it's a clear indicator of an EAB infestation and warrants immediate attention.

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Woodpecker Damage: Nature's Alarm Bell

Woodpeckers are natural predators of EAB larvae. They peck at the bark to access the larvae beneath when they detect an infestation. Thus, an increase in woodpecker activity on your ash tree can indirectly indicate EAB presence.

While woodpecker damage can be beneficial in controlling the pest population, it also indicates a severe problem. Frequent and extensive woodpecker activity on your ash tree is an apparent reason to inspect it for EAB infestation.

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Crown Thinning

As EAB larvae feed on the cambium layer, the tree's ability to transport nutrients and water is severely impaired. This results in crown thinning, where the tree's upper branches begin to lose their foliage. This phenomenon can be observed from a distance as the tree's canopy becomes increasingly sparse.

Crown thinning is a visual cue that the tree is struggling to survive. If you notice your ash tree's canopy becoming sparser, it's essential to investigate further for EAB infestation.

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"D" Shaped Exit Holes: The EAB's Signature

Adult Emerald Ash Borers exit the tree after completing their larval stage, leaving behind distinctive "D" shaped exit holes. These exit holes are about 1/8 inch in diameter and are typically found on the tree's trunk and branches. These small, D-shaped holes are a definitive sign of an EAB infestation.

When inspecting your ash tree, pay close attention to the trunk and branches for these exit holes. If you find them, taking immediate action to address the infestation is vital.

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Bark Splitting: A Visible Consequence

The tree's bark may split vertically as the Emerald Ash Borer infestation progresses. This splitting is often accompanied by other signs like "S" shaped galleries and D-shaped exit holes.

Bark splitting weakens the tree's structural integrity and provides an entry point for other pests and diseases. If you observe bark splitting on your ash tree, it's crucial to assess and address the issue promptly.

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Epicormic Sprouts: A Desperate Response

Epicormic sprouts are small shoots that emerge from the trunk or branches of a tree in response to stress. When an ash tree is under duress due to an EAB infestation, it may produce these sprouts to compensate for the loss of canopy foliage.

While epicormic sprouts may seem like a sign of recovery, they indicate severe stress and a weakened tree. They should not be mistaken for a healthy growth response. Instead, they signal the urgent need for professional intervention to save the tree.

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Contact Strobert Tree Services: Your Ash Tree Preservation Partner

If you suspect that your ash tree may be infested with Emerald Ash Borers or if you've identified any of the signs mentioned in this article, it's essential to take action promptly. Contacting certified arborists like Strobert Tree Services can make all the difference in preserving your valuable ash trees.

We are a team of Delaware arborists with extensive experience in tree care, including diagnosing and treating EAB infestations. Our expertise can help determine the extent of the infestation and recommend appropriate treatment or tree removal, if necessary.

Protecting your ash trees from Emerald Ash Borers requires vigilance and proactive measures. By staying informed about the signs of infestation and seeking professional assistance when needed, you can contribute to preserving these vital trees in our environment.


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