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Emerald Ash Borer: Tree Replacement and Treatment Strategy

We are taking a proactive approach to the Emerald Ash Borer (EAB) insect problem that has infected a majority of ash trees in the municipal tree canopy. It is estimated that EAB will destroy most of the ash tree species in Milton over the next three years.

Emerald Ash Borer is an issue that has affected ash trees throughout Southern Ontario over the last few years.

Removal and Replacement Program - Fall 2016


  • Starting Monday, October 3 until approximately late November 2016, a contractor will be removing more than 500 mature ash trees that have been infected by the EAB.
  • These ash trees are situated along several streets and in some parks and woodlots predominantly in older areas of urban Milton.
  • Removals are scheduled to occur by neighbourhood, in the following order:
    • Dorset Park

    • Timberlea 

    • Old Milton, Fallingbrook, Bronte Meadows, Forest Grove and Valley View

    • Mountain View


  • All trees that have been removed will eventually be replaced.
  • Replacement trees will come from a blend of species in order to diversify the range of species types. This helps make the municipal tree canopy more resilient to any possible future infestations that may target a particular species of plants. 
  • Some plantings are scheduled to occur after the ash tree removals in the fall of 2016, while others may not occur until the spring of 2017. This depends on the availability of certain species of trees, as well as the time of the year they are best suited for planting (e.g. spring vs. fall).

What is Emerald Ash Borer (EAB)? 

The EAB is a small green insect about half the size of a dime. The EAB was first discovered in 2002 in Michigan and has become a highly invasive pest in North America. It is believed to have been imported via wooden shipping crates or pallets.

The EAB larvae feed on the vascular tissues of the ash trees, and as a result, the trees lose their ability to use water and nutrients and the trees eventually die. There are no known domestic predators to this insect.

For more information on EAB, visit the Canadian Food Inspection Agency's website

How to Identify Affected Trees 

What do ash trees look like?

Visit the Tree Identification website to identify the tree in question by leaf, name or fruit.

How do I know if a tree is on my property or the Town's?

Please note that any affected tree not on Town property is the responsibility of the property owner to address. If you are unsure about whether an affected tree is on your property or the Town's, please contact us using the information on the left of this page. 


  1. Systemic Insecticide - There have been some positive results in using a systemic insecticide (TreeAzin) on ash trees to protect them from EAB infestation. The downside to such an approach is that the effectiveness of the insecticide treatment only lasts for about two years. After the two-year period a re-application of the insecticide would be required.  This treatment will only prolong the inevitable demise of the tree.
  2. Removal and replacement - The only other alternative is to remove and replace the tree with another species.

The Town's Emerald Ash Borer Strategy 

Our primary concern is public safety. Action must be taken to ensure ash trees do not deteriorate to the point of becoming a public safety hazard, with the potential of falling branches or even entire trees. 

Since treating all ash trees continually is not sustainable, we are using a blended approach:

  • All ash trees on Town property in good to excellent condition, with a 20 cm diameter at breast height (DBH) or larger will be considered for treatment.
  • All ash trees on Town property in fair or poor condition will be removed and replaced with a different species of tree.

What to Expect

The following potential activities will be undertaken in the Town boulevard or road allowance area adjacent to residential properties (i.e. Town-owned property):

  • Locates for services (painted lines and/or flags to identify underground utilities);
  • Objects at the base of select ash trees providing treatment to the trees;
  • Tree removals and replacements (tree replacements will occur in the fall and may not necessarily occur the year of removals);
  • Insect traps (green and yellow boxes hanging from the tree) could be found in select ash trees where infestation is expected but not yet occurring. (Staff with the Canadian Forest Service are studying EAB to research the insect and determine potential new treatments.)  

Long-Term Sustainability

Over the last several years, we have planted a blend of tree species in order to diversify the range of tree species types. Continuing this approach will help make the municipal tree canopy more resilient to any possible future infestations that may target specific species of plants. 

Project Background 

The Emerald Ash Borer Strategy is a multi-year capital project, pending annual budget approval.

The following staff reports provide details about the project history:


  • If you have any questions or concerns regarding the Emerald Ash Borer Strategy or the ice storm remedial work, please contact the Engineering Services Department at 905-878-7252, ext. 2500, or provide comments on our online reporting form.
  • Further information on caring for a new street tree can also be found on our Street Trees web page.