Latest News

Emerald Ash Borer affecting city tree canopy

Emerald Ash Borer (E.A.B.) continues to have an impact on the Oshawa tree canopy.

Forestry staff have been removing dead ash trees throughout the city that are impacted by the insect, resulting in the tree no longer being viable and potentially creating a risk to the public and/or the surrounding property. Inspected ash trees that have not lost more than 30 per cent of their live canopy will continue to be maintained and monitored by the city.

First confirmed in Oshawa in 2011, E.A.B. is an invasive insect that attacks and kills ash trees. Throughout southern Ontario, ash trees have been an important part of the tree canopy because they grow quickly and adapt well to various growing conditions. They make up a major component of woodlots, street trees, parks and natural areas. Once infested with E.A.B., the tree quickly becomes brittle and hazardous to public safety.

The city has been treating its parks and boulevard ash trees with TreeAzin since 2012, but this does not guarantee the survival of each tree. However, there has been some success in many areas such as Lakeview Park. Some areas have experienced major loss on streets, in green spaces and on the cities trail system.

Once an infested ash tree in a park or on a city boulevard is removed, the stump will be replaced by a new species of tree in the next calendar year. Since 2011, more than 1,000 ash trees have been replaced. Property owners with ash trees are responsible for managing their trees, and if concerned, should consider hiring a certified arborist to discuss options.

For more information, visit or call the Invading Species Hotline at 1-800-563-7711.