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Emerald Ash Borer (EAB)

Emerald ash borer (EAB) is a non-native invasive insect that attacks and kills all North American species of ash trees (Fraxinus species). EAB has killed tens of millions of ash trees in North America since it was first detected in the Detroit & Windsor area in 2002. It and other non-native, invasive organisms pose a serious threat to our natural systems and urban forests.

EAB Adult on LeafEAB was detected in the GTA in 2007. It is expected to decimate the region’s ash tree population over the next decade. This will have a significant economic and environmental impact including considerable tree removal costs, public safety hazards and a loss of ecosystem services. The TRCA Approach for the Management of EAB aims to limit these immediate impacts as well as focus on the long term health of our forests.

Non-native invasive insects, diseases and plants are one of the greatest threats to the biodiversity and resiliency of our forests. Emerald ash borer, Asian long-horned beetle, beech bark disease, and butternut canker are relatively recent non-native threats of concern; while chestnut blight, Dutch elm disease and gypsy moth have been impacting our forests for quite some time. Once introduced, the spread of these organisms is often accelerated or caused by the human movement of firewood and other infested material – the Canadian Food Inspection Agency has established EAB regulated areas from which the movement of certain ash material is restricted.

The most effective approach to sustainable forest management is to ensure a diverse and robust forest system that is resilient to the inevitable pest and disease outbreaks and other stressors associated with forests located within a human-dominated landscape. TRCA has a long and active history in the effective protection, restoration and management of the forest system within its jurisdiction. Our response to EAB focuses on identifying ecologically important ash stands, ensuring forest regeneration, selecting and protecting individual trees as seed sources and for EAB Treeazin Treatment & Signother values with injections of TreeAzinTM, and ensuring the safety of our parks and public spaces through a comprehensive proactive removal program for all potentially hazardous Ash trees.

Ash trees have been one of the most reliable deciduous tree species used in restoration and reforestation plantings. However, due to the threat of EAB the TRCA does not currently include ash in planting projects. A list of Tree Species to Replace the Ash Component in Restoration and Reforestation Projects in the TRCA provides information on some alternative deciduous trees.

If you are a landowner and would like more information on how your property can contribute to a regionally resilient forest system visit our private land stewardship webpage.

From Tragedy to Triumph - Re-purposing Ontario's Ash Trees
In 2002 the Emerald Ash Borer was first discovered in the province of Ontario, an insect that fed on and devoured the ash tree, a native Ontario tree.  In spite of efforts, treatment, and management plans by municipalities and conservation authorities, not all trees could be saved and it is expected millions of trees will vanish, forever altering Ontario's tree canopy.

Partners in Project Green, along with Toronto and Region Conservation, City of Toronto, City of Markham, and the Town of Richmond Hill found a way to re-purpose these trees into valuable wood products, turning an ecological disaster into a success story. Check out our videos to learn more

For more success stories visit

To learn more about emerald ash borer

To learn more about TRCA and its' Regional Partners response to EAB

If you are a homeowner and want information on EAB treatment options and guidelines for hiring tree care services

Current Ash Tree Removal Operations

Green Push Pin Marker Completed Operations Yellow Push Pin Marker Ongoing Operations Red Push Pin MarkerFuture Operations


For more information, please contact Thomas Hildebrand at or call 416-661-6600 x5379