Ash Treatment, Removal and Replacement

EAB infestation

The Emerald Ash Boer (EAB), an invasive insect from Asia, is considered to be one of the worst alien forest pests to ever be introduced to North America. Since 2002, ash trees across large portions of the United States, Ontario and Quebec have been devastated by the EAB infestation. EAB lay their eggs in ash trees. The larvae eat the soft wood under the tree’s bark, preventing the tree from moving water and nutrients between its roots and leaves, and killing it within one to three years.

Learn about the town’s Canopy Conservation, Hazard Abatement and Canopy Replacement programs.

Canopy Conservation

Oakville has one of the most aggressive management plans in Canada to combat EAB. Town Council approved a plan to treat a portion of the public ash canopy on streets and in parks with TreeAzin™, a biological insecticide.

Public ash trees receive treatment if they:

1. Do not have cracks or holes in their trunk and if 60 per cent or more of their upper branches are healthy. TreeAzin™ is effective at protecting trees that meet these criteria. If a tree is unhealthy or has cracks or holes, treatment is unlikely to prevent it from dying from EAB infestation.
2. Are at least 20 centimetres in diameter at the point on their trunk about 1.3 metres from the ground (diameter-at-breast-height or DBH). The town has determined that it is more cost-effective to remove and replace ash trees that are under 20 centimetres DBH than to treat them.

You may notice green dots and/or green ribbons on the trunks of public trees that are being treated.

Hazard Abatement – streets and active parks

To protect resident safety and property, the town will remove the remaining 25 per cent of the public ash canopy over the next few years and replace it with trees of different species.

Trees that did not qualify for treatment and are scheduled for removal are marked with an orange X and in some cases, a red ribbon.

To find trees in the Treatment and Streets and Parks Hazard Abatement programs, visit Explore Oakville maps - Street and Park Trees.

Hazard Abatement – woodlands

The town continues to treat municipal street and park trees to protect against EAB. However, the EAB infestation has had a devastating effect on our woodlands. Most, if not all of the town’s 43,000 woodland ash trees are now dead or dying. The town is removing dead and dying ash trees throughout our woodlands over a 10 year period. Learn about the Woodlands Hazard Abatement program.

Canopy replacement

The town is replacing municipal street and park ash trees with trees of different species. Trees removed in the spring or summer will be replaced the following fall or spring.

While natural regeneration will account for most of the regrowth in our woodlands, portions of select sites have been identified for enhanced and/or intensive regeneration and replanting. Learn more on our Woodland Hazard Abatement page.

What you can do

If you have an ash tree, you have two options:

1. Treat. If you have started a treatment program, great! Please continue treating. Continued treatment will help keep your tree healthy until after the infestation has died out. Treatment must take place between June and August. Due to the current infestation levels, if you have not yet begun a treatment program, it is likely too late to begin treatment to save your tree.

2. Remove. Dead and dying trees can become structurally unsound. Remove and replace untreated ash trees with a different species. Doing nothing may put you and your property at risk. For planting tips and a list of native species, visit our Tree Planting page.

Get more information on EAB by visiting the EAB resources page.

Be a canopy champion!

Plant a tree today!

Visit our Tree Planting page for a list suggested trees to plant in your area.

Adopt-an-Ash program

Please note we are not accepting new adoptions. EAB infestation is now high to extreme throughout most of Oakville. Trees not already treated will not be accepted for treatment.

To renew an adoption, please complete the form agreement for contractors to perform arborcultural services on town property (pdf).