Emerald Ash Borer




What is the emerald ash borer?

The emerald ash borer is a non-native, invasive insect that was first identified in Ontario in 2002. Since then, the insect has spread eastward across Ontario - killing millions of different types of ash trees. It was first found in south Whitby in 2011 and in Brooklin in 2014.

The early infestation of emerald ash borer is difficult to detect. The pest can be active for three to four years before any signs or symptoms are noticeable. However, bark damage left by woodpeckers feeding on larvae is one way to indicate there is serious infestation of the emerald ash borer.

What is the Town's role?

The Town of Whitby is responsible for treating or removing and replacing ash trees located on Town roads, parks, open spaces, woodlots and other municipally owned properties.

Treating ash trees


Ash trees affected by the emerald ash borer can be treated with the pesticide TreeAzin. Significant, healthy and structurally sound trees with less than 30 per cent canopy loss are the best candidates for treatment. Ash trees must be treated once every two years for about 15 years or until the threat of an emerald ash borer infestation has passed.

The life expectancy is generally longer for park trees than street trees because of location and soil differences. Therefore, the Town's efforts to save ash trees focus on trees located in parks. About 250 ash trees in various parks are being treated. 

Parks where ash trees are being treated are Heydenshore Park, Lion's Promenade, Windsor Bay Park, Lupin Park, Waterfront Trail from the Whitby Marina to Gordon Street, Iroquois Park Arena, D'Hillier Park, Brooklin Optimist Park, Selkirk Park, Whitby Kinsmen Park, Carson Park and Spencer Community Centre.

Untreated ash trees will become infested with emerald ash borer and will die within one to two years after symptoms are present.

Removing and Replacing ash trees


In 2013, about 7,700 ash trees were identified in the Town parks, open spaces and along roads.

The Town is continuing its emerald ash borer action plan and has scheduled the removal of 1,000 ash trees located in parks and woodlots for 2017.

The Town of Whitby has selected about 50 types of trees to be planted on residential boulevards where ash trees have been removed. Large, growing trees will be planted in areas that have space. Small, growing trees will be planted where space is limited, such as near street lights and between driveways. Various types of trees will be planted along all streets to ensure a diversity of species.

It is anticipated that all ash street trees removed in 2016 will be replaced in 2017.  The Town's removal of tree stumps and the planting of new trees will begin in May and will continue until November. The Town provides residents with two to three weeks' notice when any tree stumps are to be removed and any new trees are to be planted. The notice will provide detailed information on stump removal, tree planting, and tree care.

At that time, a white flag is placed on the boulevard to show the planting location. The type of tree to be planted is noted on the flag.

Residents may request a different type of tree in consultation with the Town's forestry representative. Any requests must be received shortly after a notice is received as tree species cannot be changed once the Town has placed its order with a nursery.


For a list of streets where ash trees will be replaced, please see the attached 2017 Stump Removal and Tree Replacement Schedule.

What's the role of property owners?

Property owners are responsible for maintaining, treating and removing ash trees (and any other trees) located on their property.