Emerald Ash Borer in Toronto: Treat, Remove or Wait?

What Is the Emerald Ash Borer and Why Should Toronto Homeowners Care?

The emerald ash borer (EAB) is an invasive beetle that has devastated ash tree populations across North America since its arrival in the early 2000s. This small, metallic green insect lays its eggs beneath the bark of ash trees, and when the larvae hatch, they tunnel through the wood, disrupting the tree's ability to transport water and nutrients. Within two to four years of infestation, an ash tree can be completely dead.

In Toronto, the emerald ash borer has become a serious concern for homeowners, municipalities and arborists alike. The city's urban forest contains thousands of ash trees, many of which are at risk. If you have an ash tree on your property, understanding the signs of EAB infestation and your treatment options is essential to protecting your landscape and preventing the spread of this destructive pest to neighbouring trees.

How to Identify Emerald Ash Borer Damage on Your Trees

Early detection of emerald ash borer damage can make the difference between saving your tree and losing it entirely. The most obvious sign is the appearance of D-shaped exit holes in the bark, typically about 3 millimetres wide. These holes are created when adult beetles emerge from the tree in late spring or early summer. You may also notice serpentine galleries or tunnel patterns visible just beneath the bark if you peel away a section of damaged bark.

Other warning signs include crown dieback, where the upper branches of the tree begin to thin and lose foliage, often starting at the top and working downward. The tree may also produce epicormic shoots, which are small sprouts that grow directly from the trunk or larger branches as the tree attempts to recover from stress. Woodpecker damage is another indicator, as birds feed on the larvae beneath the bark and create irregular holes and bark stripping. If you notice any combination of these symptoms on an ash tree in Toronto, contact Toronto Tree Trimming at (437) 600-1089 for a professional assessment.

Treatment Options for Ash Trees Infested with Emerald Ash Borer

If your ash tree is in the early stages of emerald ash borer infestation, treatment may be possible. The most common approach involves injecting insecticide directly into the tree's vascular system. Products containing emamectin benzoate or dinotefuran are injected annually or every two years, depending on the product and the severity of the infestation. These systemic treatments are absorbed by the tree and poison the larvae as they feed, protecting the tree from further damage.

Treatment is most effective when the tree is still in relatively good health and the infestation is caught early. However, treatment is not a one-time solution. Once you begin a treatment program, you will need to continue it for as long as you wish to keep the tree alive, which can become costly over time. Additionally, treatment works best on trees with less than 50 percent crown dieback. If your ash tree is already severely damaged, treatment is unlikely to save it, and Tree Removal may be the more practical and economical choice. Our certified arborists at Toronto Tree Trimming can assess your tree's condition and recommend whether treatment is a viable option for your specific situation.

When Tree Removal Is the Best Solution

Tree Removal becomes necessary when an ash tree is heavily infested with emerald ash borer and treatment is no longer effective or economical. If the tree has more than 50 percent crown dieback, is showing signs of structural failure, or poses a safety risk to your home or neighbouring properties, removal is often the safest and most sensible course of action. A dead or dying ash tree can become brittle and unstable, with branches that may fail without warning, especially during storms or heavy winds.

Removing an infested ash tree also prevents the spread of EAB to other ash trees in your neighbourhood. Once you decide to remove the tree, it is important to have the wood chipped or properly disposed of rather than left as firewood or mulch, as this can transport the beetle to other areas. Toronto Tree Trimming provides professional Tree Removal services with complete cleanup and site restoration. We understand the regulations around ash tree removal in Toronto, and our team will ensure the work is completed safely and in compliance with local requirements. Contact us at (437) 600-1089 or request a free estimate to discuss your options.

The Wait-and-Monitor Approach for At-Risk Ash Trees

Not every ash tree in Toronto is currently infested with emerald ash borer. If your ash tree shows no signs of EAB damage and is still healthy, you may choose to monitor it rather than take immediate action. This approach allows you to avoid the cost of treatment or removal while keeping a close eye on the tree's condition. Regular monitoring involves inspecting your tree two to three times per year, particularly in spring and early summer when adult beetles are most active and exit holes are most visible.

During your monitoring period, maintain the tree's overall health through proper Tree Trimming and care. A healthy, well-maintained ash tree is better equipped to withstand pest pressure and environmental stress. However, be prepared to act quickly if you notice the first signs of infestation. The sooner you detect EAB damage, the more treatment options remain available to you. If you are uncertain about your tree's current status or want professional guidance on whether monitoring is appropriate for your situation, Toronto Tree Trimming's certified arborists can perform a thorough evaluation and provide recommendations tailored to your property.

Getting Professional Help: Why You Need an Arborist

Deciding whether to treat, remove or monitor an ash tree is not a decision to make alone. A certified arborist brings expertise in tree health, pest identification and the long-term implications of each option. Our team at Toronto Tree Trimming can assess the extent of emerald ash borer damage, evaluate the tree's structural integrity and overall health, and recommend the most cost-effective and appropriate course of action for your specific situation.

Professional assessment also matters when you are applying for a permit from the City of Toronto. Many ash tree removals in the city require municipal approval, and an arborist report documenting the infestation or structural risk can support your application and expedite the process. Whether you choose treatment, removal or monitoring, having a professional evaluation on record protects you and demonstrates responsible stewardship of your property. To schedule a free consultation with one of our ISA Certified Arborists, call Toronto Tree Trimming at (437) 600-1089 or visit https://toronto-tree-trimming.ca to request a free estimate. We serve the Toronto area and are ready to help you protect your trees and your property.