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The emerald ash borer has spread throughout most of the Grand River watershed and will probably kill almost all ash trees, except for the smallest.
The beetle, originally from Asia, arrived in southwestern Ontario in 2002 and the Grand River watershed in 2010. Usually, the beetle kills almost all ash trees within a decade of being detected.
The beetle's larvae tunnel under the bark of an ash tree and cut off the tree's supply of nutrients and water. The tree dies from the inside out. Once an ash tree starts to decline, it could quickly be at risk of falling over, damaging property or hurting people.
The GRCA has a strategy to address the challenge on its own properties. The cost could be about between $4 million and $8 million over the next decade.
Municipalities throughout the watershed also face costs in the millions of dollars to remove ash trees in their parks, along city streets and near trails. Private property owners also have to deal with dying ash trees on their own properties.
What the GRCA is doing
Removing hazard trees
Ash trees are common on GRCA properties. The GRCA's strategy is to remove ash trees that pose a threat to people and property. That means cutting them down in campgrounds, along trails, near buildings and in other areas used by people.
GRCA staff assessed the ash trees in these areas to determine their health and the level of risk they pose. The trees will be removed and new trees planted as required.
Managing forests
In forested areas where there is little or no human activity, the trees will be allowed to die on their own. In most forests, the percentage of ash trees is low, so the ecological integrity of the forests will not suffer much.
In a few forests - about 800 hectares or 10 per cent of the GRCA's forested land - the percentage of ash trees is about 30 per cent. Those forests will be studied to determine the best way to manage the loss. The approach may change from area to area, depending on local conditions.
Treating trees
An insecticide called TreeAzin protects ash trees from the borer. However, it is relatively expensive and trees need to be treated for up to 10 years.
The GRCA is treating 200 trees in an effort to preserve the species within the watershed. Some trees are being treated because they are in high use areas (e.g. beaches, campgrounds) and provide a lot of value to users.
The GRCA will spend $15,000 each year to treat the trees.
More information
- Emerald ash borer - website of the Ontario Ministry of Natural Resources and Forestry
- Emerald ash borer - website of the Canadian Food Inspection Agency
- A visual guide to detecting emerald ash borer damage - Publication of Natural Resources Canada (PDF)
- Landowners guide for woodlots threatened by emerald ash borer - Publication of the Ontario Ministry of Natural Resources and Forestry (PDF)
