The Emerald Ash Borer beetle is a non-native invasive insect that attacks and kills most varieties of ash trees.
Adult EAB beetles lay their eggs on ash trees in the summer. When the eggs hatch into larvae, they tunnel under the tree's bark to feed. The tunnels prevent the flow of water and nutrients, causing the tree to die. As larvae, they are located between the bark and sap wood. As adults, EABs eat ash tree leaves. Both of these actions, including the fact that EABs do not have any natural predators, lead to infestation and eventual death of the tree (in approximately 1 to 4 years).
In order to deal with the threat posed by EAB, the City of Cornwall's EAB management plan (see below) involves a combination of:
|Tree Removal||Tree Injection|
Ash trees in the community that have been marked with an orange line on the trunk and an information sign posted on the tree will be removed.
When the tree is removed, all limbs will be chipped and wood will be removed off site. The stump will be removed at a future date and if space permits, a new tree will be planted.
Ash trees in the community that have been marked with a green dot at the base of the trunk are candidates to be treated with TreeAzin to protect it against the EAB.
TreeAzin is a systemic insecticide injected into the tree's bark to kill EAB larvae feeding on the tree's tissues. It does not pose any health risk to people, pets or wildlife and degrades naturally. It is re-injected in the tree every two years.
At the City Council meeting of March 24th, 2014, City Council passed a motion to adopt an "active management" plan to deal with the EAB threat to ash trees on City-owned property, including streets, parks and other public spaces.
Under this management strategy, the City will undertake a more active approach to the EAB infestation by removing dead ash trees, re-planting on a 1:1 ratio with a different specie and adding the pre-emptive removal of ash trees in order to spread the cost of removal over 15 years.
This management plan also introduces the biannual treatment of existing mature ash trees that are in good condition and are greater or equal to 30 cm diameter at breast height (DBH) in order to maintain some of the City's tree canopy until the new plantings are large enough to provide all of the benefits that mature trees provide to the environment. The selected trees are injected with TreeAzin ( azadirachtin) every two years.
Good condition refers to the following criteria:
"Safe useful life expectancy in excess of 20 years, visual importance, forming component part of significant ash species cluster/group/avenue/feature, few adjacent trees, pruning intervention unlikely, few or no above/below ground conflicts, 'heritage' candidate tree, providing significant environmental and other benefits and/or high cost to remove if tree dies."
The cost of implementing this approach if the City decides to treat 100% of the ash trees that meet the "Good condition" criteria is anticipated to be $5.9 million over 15 years. The cost decreases as the percentage of trees selected for treatment decreases.
This management approach has been recommended by both the City's Municipal Environmental Advisory Committee and the Recreation Advisory Committee. It is based on the Emerald Ash Borer Management Plan that was prepared for the City of Cornwall by Urban Forest Innovations Inc. (the full document is available below).
Here are some answers to commonly-asked questions regarding the emerald ash borer. Images are courtesy the Ministry of Natural Resources.
The EAB beetle is a non-native invasive insect, that attacks and kills most varieties of ash trees (white and green ash). Adult EAB beetles lay their eggs on ash trees in the summer. When the eggs hatch into larvae, they tunnel under the tree's bark to feed. The tunnels prevent the flow of water and nutrients, causing the tree to die.
The EAB beetle originated in Asia, and is believed to have come to North America in the early 1990's, via the transportation of ash wood materials. It was first detected in Canada in 2002 in Windsor, Ontario. It has since killed and infested over 70 million ash trees.
The most common way for the emerald ash borer to spread is through people moving infested materials such as firewood. To prevent the spread of EAB, don't move firewood, and buy wood locally. Scientists in Canada and the United States have concluded that the emerald ash borer cannot be eradicated. In light of this the Canadian Food Inspection Agency (CFIA) adopted a "slow-the-spread" approach. To help limit the spread, ministerial orders have been put in place to regulate areas infested by the pest. The CFIA is the federal governing body responsible for exotic insects.
EAB kills ash trees by eating their nutrients. As larvae, they are located between the bark and sap wood and eat the trees nutrients. As adults, EABs eat ash tree leaves. Both of these actions, including the fact that EABs do not have any natural predators lead to infestation and eventual death of the tree (approx. 1 to 4 years).
EAB has been confirmed in the northeast quadrant of the city. However, EAB beetles can fly long distances up to 5 km, and is suspected to be present throughout the city.
There are a number of possible signs that could indicate a possible EAB infestation.
Dead branches or discolored foliage which can be observed during late summer. Feeding by the larvae kills branches and eventually the trees (approx. 1-4 years). See Figure 1.
Epicormic shoots: These shoots are also called suckers, water sprouts or witches broom and are produced on the tree trunk and roots when the tree is under stress. They can sometimes be found in the tree crown, on stems and on larger branches. Not all trees attacked by the Emerald Ash Borer develop epicormic shoots. However, under the right conditions and intensity of attack by the beetle, they can develop and grow quickly. See Figure 2.
Woodpeckers feed on the larvae under the bark. Look for increased Woodpecker feedings or signs of their robing in the bark. See Figure 3.
Close examination of the bark may reveal D-shaped holes. When new adults emerge from the tree they create this hole to leave the tree. These holes are approximately 3.4 to 4 mm wide. See Figure 4.
Vertical splits of the bark of 7 - 10 cm are often present over larval galleries. These are often more noticeable on young trees that do not already have splits from growth-related expansion. See Figure 5.
If the bark is peeled back S-shaped tunnels may be visible. This is from the larva feeding between the bark and sap wood. See Figure 6 and 7.
TreeAzinâ„˘ is a systemic insecticide injected into the tree's bark, directly into the conductive tissues, and moves upward with the flow of water and nutrients. It kills EAB larvae feeding on the tree's tissues by regulating growth and disrupting normal molting. It does not pose any health risk to people, pets or wildlife and degrades naturally. To be effective, it is re-injected into the tree every two years.
Ash trees make up approximately 21% of the town's urban forest, on public property and 25-30% on private property. The Urban Forest has an inherent value and provides us with numerous benefits - helping clean the air we breathe, shading us from harmful UV rays, beautifying our city and many others. Untreated ash trees are expected to be impacted or killed by EAB over the next 10 years.
The City is currently implementing its EAB Management Strategy, which aims to reduce the significant aesthetic, environmental and financial impacts of the EAB. This is being done through a combination of monitoring, treatment, ash tree removal and replacement, and public education. Private property owners are responsible for trees on their property.
Property owners are responsible for the care of privately-owned trees. The City of Cornwall recommends you monitor the condition of your tree and look for signs of infestation. If you see signs that your ash tree is dead or dying, you should contact a professional tree care company. If an emerald ash borer infestation is detected early, you may consider asking your tree care company to assess whether the tree may benefit from injections.
Property owners who suspect an EAB infestation are encouraged to contact a professional arborist. Private property owners are responsible for trees on their property.
City staff require your assistance to monitor the health of City trees in your neighborhood. If a City tree appears to be in decline, please advise the Parks and Landscaping Section at (613) 930-2787 ext. 2264. The tree will be assessed by a certified arborist and appropriate best arboricultural practices will be applied to maintain the urban forest.
City of Cornwall, Parks and Landscaping Section
(613) 930-2787 ext. 2264
The Canadian Food Inspection Agency
Canadian Forest Service