Emerald ash borer


One of the most prevalent pests of the past decade has been emerald ash borer (EAB) - an invasive tree beetle that has killed millions of ash trees across eastern North America, including many in our own community.

In an effort to minimize the devastation this fast-spreading pest can cause, we developed an EAB management plan using our tree inventory data, a survey of our local ash tree population, and through a trap sampling program used to initially track the rapid spread of the problem.

Over the past few years, we've taken effective steps to reduce EAB in our community, which include:

  • Injecting hundreds of ash trees with a pesticide called TreeAzin™ to protect them against EAB, and
  • Removing potentially infested ash trees along streets and in parks.

    Monitoring injected ash trees

    Protected ash trees are monitored and injected at least every two years. More frequent injections are needed when EAB populations are at their peak.

    Unfortunately, some ash trees can be infected by EAB despite the chemical injections. In these cases, infestation is likely too advanced for the treatment to be effective.

    Removing infested ash trees

    Declining and damaged ash trees with one or more of the following characteristics are removed as required:

    • Canopy loss greater than 30 percent;
    • Bark deformities;
    • New twig growth (epicormic growth) on the trunk;
    • Woodpecker feeding holes;
    • Large wounds.

    The following map shows the work that has been completed to date, along with our planned work for 2017 and 2018.

    Proactive ash tree removals along city streets and in active parkland will be completed by the end of 2017.

    Replacing ash trees

    To date, we've replaced more than 1,100 ash trees that were infested with EAB and removed across about half of our city, and more tree plantings are planned.

    The following map shows the areas of the city where new plantings have occurred, and the areas we'll be focusing on soon.


    What is EAB?

    EAB is an introduced and destructive tree pest that kills ash trees. Larvae that are feeding beneath the bark disrupt the tree's circulation of water and nutrients, eventually causing the tree to die. All species of ash are susceptible to EAB, except for mountain ash, which is not a true ash species. Once infested, trees typically succumb to EAB within two to three years. For more information on EAB, please visit Natural Resources Canada.

    How will I know if an ash tree near my home is going to be removed?

    Each tree will be marked with two vertical pink dots.

    The ash tree near my home is healthy; why is it being removed?

    Unfortunately, ash trees that have not been chemically injected to protect them from EAB are assumed to host an infestation. The initial stages of infestation are difficult to detect and infested trees can appear healthy. When the signs and symptoms of infestation are evident, the tree will begin to decline rapidly and die.

    Why wasn't the ash tree near my home injected with TreeAzin?

    When the injection phase of the EAB management plan began, trees identified as potential candidates for injection had to:

    • Be 30 cm. or more in diameter based on a measurement made at 1.4 m. above ground level; and
    • Exhibit a healthy tree crown.

    Streets with a high number of ash trees, which met the above criteria, were given priority for injection, as were significant ash trees in parks.

    To be effective, TreeAzin™ injections are required at least every two years. Due to these ongoing, high injection costs, we cannot inject every city-owned ash tree.

    The ash tree near my home was injected with TreeAzin; why is the tree now being removed?

    The EAB infestation in the tree was likely too advanced to be effectively controlled by TreeAzin™. The ash tree has likely declined and further injections are no longer warranted; as a result, the tree has been identified for removal.

    Will the city consider injecting the ash tree near my home now?

    No, unfortunately any ash tree that has not been injected with TreeAzin™ is assumed to host an EAB infestation. The injections are most effective at preventing EAB from infesting an ash tree. Consequently, an ash tree injected now would likely succumb to EAB despite the injection.

    Can I inject a city tree near my home?

    No, we will not assume the liability of a homeowner injecting our trees.

    Why don't you leave an EAB-infected ash tree standing until it begins to decline?

    Ash trees infested with EAB can become unstable and fall, posing significant safety risks. Heavily infested trees are also more hazardous and costly to remove.

    When will an ash stump be removed?

    A stump removal program will begin in the spring after an ash tree is removed; the program is typically completed by the end of the year. At the time of removal, an ash tree will be cut as low to the ground as possible. The stump will be ground out and restored with new top soil and grass seed.

    Will a removed ash tree be replaced?

    Each ash tree removed will be considered for replacement. Tree replacement locations are assessed on a case-by-case basis. Locations that have a confined growing space due to a small boulevard, and/or locations where a tree's physical size could conflict with existing infrastructure, such as driveways, lamp posts, hydro vaults, and fire hydrants, may not be replaced.

    Priority is given to replacing street trees, followed by park trees. A tree replacement plan is developed in the fall, after stump removal has taken place; a replacement planting is planned for the following year.

    How big will the replacement tree be?

    Our standard size for all new tree plantings is two to three metres - or eight to 10 feet - in height.

    What should I do if I have an ash tree on my property?

    Trees on private property are the responsibility of the owner. We encourage property owners to discuss their options with a professional tree-care company and determine if it's worthwhile to protect their ash trees. You can learn more about protecting your ash tree and find qualified contractors by visiting the Bioforest website. We suggest getting at least three estimates before starting any work.


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