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Emerald Ash Borer: Treating Infestations vs. Tree Removal

Ash trees are beautiful and valuable additions to any landscape, offering lush canopies and vibrant colors in the fall. However, the invasive species known as the Emerald Ash Borer (EAB) poses a significant threat to the health and survival of these trees. Homeowners, gardeners, and urban foresters are faced with the difficult decision of whether to treat the trees or remove them completely in the face of an infestation. This comprehensive guide is designed to help you navigate through the complex and challenging landscape presented by EAB to ensure the optimal outcome for your ash trees.

The Emerald Ash Borer is an invasive beetle species native to Asia that was accidentally introduced to the United States in the early 2000s. They have been wreaking havoc on American ash tree populations ever since, leading to the death and decline of millions of trees across the country. The adult beetles nibble away on ash tree foliage, leaving behind only minimal harm. However, it’s the larvae that do the real damage by burrowing beneath the tree’s bark, disrupting the flow of water and nutrients throughout the tree and eventually killing it.

The best course of action when faced with the Emerald Ash Borer crisis is to be proactive in identifying, treating, or removing infested ash trees. In this guide, we will dive deep into the available treatment options, discuss the best timing for treating or removing the trees, and help you make an informed decision about what’s best for your property and the overall ecosystem. Treatment options can range from injecting pesticides into the tree to biological control methods that use natural enemies of the Emerald Ash Borer.

By thoroughly understanding the behavior and vulnerabilities of this devastating invasive species, we can equip ourselves with the tools and knowledge to make the best decisions regarding the management of our ash tree populations. So let’s explore when to treat or remove ash trees affected by the Emerald Ash Borer and provide your trees with the best possible chance at a long and healthy life.

Identifying the Signs of Emerald Ash Borer Infestation

Before deciding whether to treat or remove an ash tree, it is essential to confirm the presence of an Emerald Ash Borer infestation. Early detection and intervention can determine the appropriate course of action to prevent further damage and save the tree if possible. Here are the key signs of EAB infestation:

1. D-shaped exit holes: As adult beetles emerge from underneath the bark, they create small, D-shaped holes on the tree’s surface. These holes are about 1/8-inch in diameter and can be found in clusters or spread throughout the tree.

2. S-shaped larval galleries: The burrowing action of EAB larvae creates S-shaped meandering galleries underneath the bark. These galleries are often packed with fine sawdust and frass, and can cause the bark to split and reveal their presence.

3. Crown dieback: As the larvae disrupt water and nutrient uptake, the tree’s canopy will begin to thin and exhibit dieback signs, starting from the top and progressing downward.

4. Epicormic shoots: Stressed by the EAB infestation, the tree may begin to produce sprouts or epicormic shoots at its base or trunk in a last-ditch effort to survive.

5. Bark splitting and woodpecker activity: Woodpeckers feeding on EAB larvae can cause irregular bark splitting and peeling, as they remove bark in search of their prey.

Treatment Options for Emerald Ash Borer Infestations

Once the presence of an EAB infestation is confirmed, it is essential to determine whether or not treatment is beneficial. Treating a tree that has already suffered significant damage may not be effective. However, if caught early, the following treatment options can help save a tree from the Emerald Ash Borer.

1. Insecticides: Systemic insecticides, specifically emamectin benzoate and imidacloprid, are effective for protecting ash trees from EAB infestations. These insecticides need to be applied by a professional arborist as they involve trunk injections or soil application. Depending on the product, these treatments may protect the tree for one to two years before reapplication is necessary.

2. Biocontrol: To curb the spread of EAB, researchers have identified several biological control agents. Parasitic wasps, native to the beetle’s original habitat in Asia, have been found to be effective in controlling EAB populations. These harmless wasps lay their eggs on or inside EAB larvae, eventually killing them. The implementation of biocontrol options is often handled by federal or local agencies and is typically not available for individual homeowners.

Factors to Consider When Deciding on Treatment

The decision to treat an ash tree depends on several factors, including the extent of the infestation, the tree’s health, location, and the potential costs of treatment. Here are some critical considerations for determining whether to pursue treatment:

1. Infestation extent: Trees with less than 30% canopy decline have a better chance of recovery with treatment.

2. Tree health: Healthy ash trees can respond well to treatment and exhibit improved growth. Trees with existing structural issues or diseases may not benefit from treatment against EAB.

3. Location: If a tree is situated near buildings, power lines, or other areas where falling branches or the tree itself could cause damage, it may be more prudent to remove it rather than attempt treatment.

4. Costs: Treatment can be expensive and ongoing, as most insecticide options require reapplication every one to two years. Depending on the value of the tree, the costs may outweigh the benefits of attempting to save it.

Tree Removal: The Last Resort

In some cases, tree removal may be the only viable option. Trees with significant canopy decline or damage due to EAB are at a higher risk of dying and can pose a hazard to people and property in the area. Furthermore, removing heavily infested trees can help slow the spread of EAB to nearby healthy ash trees.

When removing an infested ash tree, it is crucial to follow all local guidelines and regulations regarding disposal, as improperly discarding infested wood can contribute to the spread of EAB. Consider working with a certified arborist to ensure the safe and efficient removal of the tree.


The fight to save ash trees from the Emerald Ash Borer requires vigilance, timely action, and informed decision-making. By closely monitoring your ash trees for signs of infestation, understanding the available treatment options, and considering vital factors such as the extent of the infestation and tree health, you can make the best decision for preserving these valuable trees.

In cases where treatment is no longer effective, or a tree poses a significant risk to its surroundings, tree removal may be the only appropriate course of action. With the help of knowledgeable arborists and adherence to local regulations, the removal of infested trees can contribute to the overall efforts to slow the spread of EAB and protect healthy ash populations. Contact On Point Solutions for the best tree services

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