What is the Emerald Ash Borer?
In North America, the borer is an invasive species, highly destructive to ash trees in its introduced range. The Emerald Ash Borer (the EAB) has the potential damage of this insect rivals that of Chestnut blight and Dutch Elm Disease.
Since its accidental introduction into the United States and Canada in the 1990s, it has killed at least 50 - 100 million ash trees so far and threatens to kill most of the 7.5 billion more. The insect threatens the entire North American Fraxinus genus, unlike past invasive tree pests, which have only threatened a single species within a genus. The green ash and the black ash trees are preferred. White ash is also killed rapidly, but usually only after green and black ash trees are eliminated. Blue ash displays some resistance to the emerald ash borer by forming callous tissue around EAB galleries; however, they are usually killed eventually as well.
The EAB only attacks true ash trees. These include green, white, black and blue ash. In Centre Wellington, green, white and black ash are the most common species with some European ash. Mountain ash and prickly ash have ash in their name but are not from the same species and are not susceptible to the EAB.
TVC News tonight featured Toni Ellis of Neighbourwoods on the Grand in a segment about the Emerald Ash Borer. To view the video, please click here!
How can I identify an ash tree?
Opposite branch and bud arrangement - Branches and buds grow directly across from each other and not staggered. Please note that the growth may be affected by pruning and death of a branch.
Compound leaves - Leaves are compound and composed of 5 to 11 leaflets. Leaflets may be smooth or toothed.
Bark - On mature trees, the bark is tight with a distinct diamond-shaped pattern. On young trees bark is grey and relatively smooth.
Seeds - Ash tree seeds are dry and oar-shaped. They usually occur in clusters and typically hang on the tree until late fall or early winter.
Need help identifying an ash tree? Bring your cell phone.
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Signs of the Emerald Ash Borer
EAB tunnels underneath the bark of ash trees and destroys its vascular system, killing the tree within five years of initial infestation. Unfortunately, signs of EAB usually only become apparent once a tree is heavily infested. Early symptoms include loss of green colour in the uppermost leaves and thinning of the crown.
The following are signs and symptoms your ash tree may be infested:
- The leaves in the top third of the ash begin to die back.
- New branches begin to grow from the low trunk or roots.
- Under the bark there are white lines or canals. These larval feeding galleries are typically packed with sawdust and excrement.
- The bark on the tree begins to split.
- There are D-shaped exit holes formed by adult beetles exiting the tree.
- There is an increased woodpecker activity that creates large holes in the tree.
Although your tree may have some signs of EAB infestation, other diseases/infestations may be affecting your trees growth. It is recommended you have a certified arborist inspect your tree before you begin treatment.