Emerald ash borer

The emerald ash borer (EAB) has killed hundreds of millions of ash trees since it was first detected in North America in 2002. This beetle was found in our watershed in 2010 and it is now present throughout the watershed. In many areas, the majority of ash trees have now died or are in serious decline.

The beetle's larvae tunnel under the bark of ash trees and cut off a tree's supply of nutrients and water. Once an ash tree starts to decline, it can quickly be at risk of falling over, damaging property or hurting people. Conservation Authorities, municipalities and private property owners have had to remove thousands of dying ash trees from near buildings, in parks, along city streets and near trails.

The loss of trees has had a significant impact on the ecological services our forests and urban trees provide. The decrease in biodiversity lowers our forests' resilience and ability to respond to stresses like climate change.

What the GRCA is doing

Removing hazard trees

Ash trees were common on our properties. Over the past decade, we have had to remove over 16,000 ash trees in campgrounds, along trails, near buildings and in other areas used by people. These tree removals have cost close to three million dollars.

Treating trees

We are treating 150 ash trees on our properties in an effort to preserve them. It's important to preserve trees because they will be a genetic resource for the future. As well, some are in high use areas like beaches and campgrounds, where they provide a lot of value to visitors.

The trees are being injected with Treeazin, an organic pesticide. Treeazin lowers the number of beetle larvae under the bark and significantly increases a tree's chance of survival.

Property Closures

There are property or trail closures in several areas where the number of ash trees is high and public use is low or moderate. This allows us to focus our tree removal resources on areas of higher use and risk.

The closed properties include:

  • Trail at the south end of Wrigley Lake in the Township of North Dumfries;
  • Small island and adjacent forest in the eastern portion of Byng Island Conservation Area in Dunnville;
  • Entire property and associated trail at Hosack Tract in the Township of Blandford-Blenheim; and
  • Trails on the western half of the Apps’ Mill Nature Centre property in the County of Brant. (The Cleaver Road parking lot with adjacent access to Whitemans Creek remains open.)

Long term decisions regarding trails and public access on these properties will be reviewed.

Managing forests

In many of our forests, ash trees make up a small percentage of the trees present. In areas where there is little human activity, the dead and declining trees have been left for habitat -- first as standing dead trees and then as fallen logs. In some of our forests, ash were the most common tree. These areas have been most significantly impacted by EAB. In a few of these areas, a 'transitional harvest' method was used. Some of the ash trees were removed before they could decline, to make the overall loss of ash trees more gradual and to lessen the damage to other trees that would have been caused by large numbers of them falling over. 

More information

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