The emerald ash borer (EAB) is a highly destructive, non-native, wood-boring beetle that feeds under the bark of ash trees, ultimately killing them. The City has been monitoring its presence since it was first discovered in Canada in 2002. The EAB was confirmed in the south end of Guelph in the fall of 2011 and in 2013, testing confirmed that the EAB was present throughout the city. Now established, it is expected to destroy close to 100 per cent of Guelph’s untreated street, park and woodland ash trees. In response, the City developed and is implementing a plan to handle the EAB infestation of City-owned trees, which includes inventory and monitoring, treatment, removal and replacement of trees, communication and public outreach.
While the City plan outlines the measures to be taken for trees on City property, much of the community’s urban forest is located on private land. It is important for residents and land owners to watch for signs of EAB on their property and know their options for managing an infestation.
January 16, 2017
August 5, 2014
June 10, 2013
What you need to know about EAB
The emerald ash borer (EAB) is a metallic green wood-boring beetle about 8.5-14 mm long and 3.1-3.4 mm wide that attacks all native species of ash trees.In its larval form (like a caterpillar), EAB feeds in an S-shaped pattern just under the bark, in the sapwood, of ash trees. This feeding disrupts the tree’s transportation of water and nutrients. Once larvae finish feeding under the bark, they mature into adult beetles that chew their way out of the tree through D-shaped exit holes. Infested ash trees in North America generally die after two to three years, but heavily infested trees have been observed to die after one year of beetle attack.
What species of trees are susceptible?
EAB has been found to attack and kill all North American species of ash (Fraxinus spp.). Mountain ash (Sorbus spp.) is not related to ash trees and is not attacked by EAB. Not sure if you have an ash tree? Visit Ontario Trees for help identifying the various species of ash trees.
Signs of EAB infestation
Signs of EAB infestation usually only become obvious once a tree has been heavily infested, and include:
- Loss of leaves and dead branches in upper part of the tree,
- Yellowing leaves,
- Adult beetles feeding on leaves,
- Unusually high woodpecker activity,
- Long shoots growing from the tree trunk,
- Vertical cracks in the tree trunk,
- S-shaped tunnels under the bark (filled with sawdust), and
- Small D-shaped holes.
Please note, not all ash trees that are losing their leaves are a result of EAB. Some instances may be a matter of general ash decline.
Managing an EAB infestation
It is the responsibility of property owners to manage an EAB infestation on private property. Trees can be managed either through treatment or removal.
Trees are an important part of our daily lives and are beneficial to the environment. There is no immediate need to cut down ash trees on your property. Affected trees will eventually die, but trees do not need to be removed until they become a hazard. If you suspect an ash tree on your property is infested contact a certified arborist and arrange an inspection. You can find tree care companies and arborists in the Yellow Pages under “Tree Service” or visit the International Society of Arboriculture website.
TreeAzin®, a natural pest control product registered under the Pest Control Products Act for use against the emerald ash borer, is recommended by both the Ontario Ministry of Natural Resources and the Canadian Forest Service as the best option. It has low toxicity to mammals and birds and has little effect on non-target organisms such as bees or beneficial insects. The active ingredient is Azadirachtin, derived from the fruit of the neem tree and it kills insects by interfering with their larval development. In order to be effective it must be injected into the tree by a licensed professional arborist using a special application device.
In order to absorb the product, trees must be in good health and relatively free from EAB. Heavily or moderately infested trees are unable to uptake TreeAzin® and should not be injected. For this reason, treatment must begin before the tree is heavily infested and injections are required every two years to keep the tree healthy during the span of the infestation.
Treatment costs can fluctuate depending on size of tree and how many trees need to be treated. For more information about TreeAzin®, including a list of service providers, visit bioforest.ca.
Some of Guelph’s ash trees may still be worthy candidates for treatment; check with a professional to assess your tree’s prospects. TreeAzin® was the treatment used by the City of Guelph for 554 City-owned trees during summer of 2014, and is also used with success by many municipalities and private landowners. The insecticides ACECAP® and Confidor have also been approved for use against EAB in Ontario.
If you have an ash tree that is too infested to be treated effectively, it could become a hazard. Dead limbs, or even the entire tree, could fall, posing risks to safety and property for property owners as well as their neighbours. Property owners are responsible for removing and disposing of hazardous limbs and trees from their properties at their own cost. A dead or dying ash tree becomes high risk and may be a violation of the City’s Property Standards By-Law.
To have infested limbs or trees removed safely, contact a certified arborist or forester. You may want to get more than one quote to insure that you get a competitive price for the service. We encourage you to plant a new native tree species to replace the lost tree canopy.
The City’s Tree By-law may affect tree removal on property larger than 0.2 hectares (0.5 acres), and a tree removal permit may be required. Please contact the City as you may be eligible for an exemption from a tree removal permit if the tree is found to be infested with EAB.
Frequently asked questions
What is the emerald ash borer (EAB)?
Emerald ash borer is a highly destructive wood-boring beetle that feeds under the bark of ash trees (Fraxinus spp.). All species of ash are susceptible to attack, except mountain ash (Sorbus spp.), which is not an ash species. EAB has killed a large number of ash trees in southwestern Ontario and many parts of the United States and poses a major economic and environmental threat to urban and forested areas across Canada and the U.S.
How does the emerald ash borer affect trees?
In its larva form (like a caterpillar), emerald ash borer feeds in an S-shaped pattern just under the bark of ash trees. This feeding disrupts the tree’s transportation of water and nutrients. Once larvae finish feeding under the bark, they mature into adult beetles that chew their way out of the tree through D-shaped exit holes. Infested ash trees in North America generally die after two to three years, but heavily infested trees have been observed to die after one year of beetle attack.
How do I know if I have an ash tree?
Visit Ontario Trees for help identifying the various species of ash trees.
How do I know if my tree is infested with the emerald ash borer?
Property owners can look for loss of leaves and dead branches in the upper part of ash trees, unusually thin tree crowns, branch and leaf growth in the lower part of the stem where growth was not present before, and unusually high woodpecker activity. Homeowners can also look for bark splitting, S-shaped grooves beneath the bark caused by larval feeding, and D-shaped exit holes 3.5–4 mm wide caused by adult beetles. Please note, not all ash trees with thinning crowns are a result of emerald ash borer, and may be a matter of general ash decline.
What do I do if I suspect my ash tree is infested?
Contact a certified arborist or forester to inspect private trees. You can find tree care companies and arborists in the Yellow Pages under “Tree Service” or visit the International Society of Arboriculture website at treesaregood.org.
For suspected emerald ash borer infestation on City property, please contact the Parks Department at 519-837-5626 or email@example.com for further investigation.
Do I need a permit to remove an ash tree on my property?
Privately-owned trees are the responsibility of the owner. The City of Guelph encourages property owners to continually inspect their ash trees for signs of infestation and to contact a certified arborist for more information. Residents removing ash trees from private property must comply with the Private Tree Protection By-law.
Where can I dispose of EAB infested ash material?
Residents can dispose of infested ash material at the City’s Waste Resource Innovation Centre, located at 110 Dunlop Drive. A disposal fee of $75/metric tonne will apply as the infested ash material is treated as waste.
How is the emerald ash borer spread?
The movement of infested materials such as firewood, logs, branches, nursery stock, chips or other ash wood is the most common way the emerald ash borer has been spread. Adult emerald ash borer can fly, but research indicates adults usually fly a short distance.
Where in the city has the emerald ash borer been confirmed?
The emerald ash borer was first confirmed in the south end of the city in the fall of 2011. These trees were promptly removed by City staff. In June 2013, fifteen infected trees were found in the same area and were removed. Further testing in 2013 confirmed that the EAB adults were present throughout all areas of the city. Further monitoring in May-June 2014 suggests that infestation is currently still concentrated in the south end of the city.
What is the City’s plan for addressing the emerald ash borer?
The City’s EAB plan includes inventory and monitoring, treatment, removal and replacement of City-owned ash trees over a 10 year period.
The basic principles of the plan are to:
- Ensure safety of people and property, as they relate to dead or dying City-owned ash trees.
- Reach out to the community to ensure they are aware of the issue, their options, and how to access their options.
- Treat as many ash trees as feasible, but only invest in the very best candidates. Feasibility here includes both financial and biological constraints.
- Set recovery into motion as quickly as possible, even before ash-tree decline, if possible.
- Protect natural areas from ecological degradation caused by EAB infestation.
- Leave infested but “green” City-owned ash trees standing as long as they are safe to stand, to gain the longest “service life” from each mature ash.
What is the cost of implementing a City wide emerald ash borer management strategy?
The estimated total cost to manage the infestation is $6 to 8 million, over the infestation’s entire course. The duration of Guelph’s infestation cannot be accurately predicted, but a decade or less is reasonable to expect. To date, the City has spent $742,779.
Is there anything that can be done to prevent the spread of the emerald ash borer?
The two most important things residents can do is to report suspected emerald ash borer infestations or outbreaks to the City at firstname.lastname@example.org or 519-837-5626; and buy and use your firewood locally.
Is there an effective treatment for ash trees against the emerald ash borer?
TreeAzin®, a natural pest control product registered under the Pest Control Products Act for use against the emerald ash borer, is recommended by both the Ontario Ministry of Natural Resources and the Canadian Forest Service as the best option.
TreeAzin® is the product of choice because it has low toxicity to mammals and birds and has little effect on non-target organisms such as bees or beneficial insects. The active ingredient is Azadirachtin, derived from the fruit of the neem tree, kills insects by interfering with their larval development.
In order to be effective it must be injected into the tree by a licensed professional arborist using a special application device. In order to absorb the product, trees must be in good health and relatively free from EAB. Heavily or moderately infested trees are unable to uptake TreeAzin® and should not be injected. For this reason, treatment must begin before the tree is heavily infested and injections are required every two years to keep the tree healthy during the span of the infestation.
Cost varies with tree size, but a mid-sized tree could be treated for about $200. The environmental services generated by that same tree are valued at about one hundred dollars or more annually. That is to say, the value of benefits provided by the tree can be comparable to, or even greater than, the investment in treatments.
TreeAzin® is the treatment that the City of Guelph is using on select City-owned trees and is currently being used with success by several of Guelph’s neighbouring municipalities, the Grand River Conservation Authority, and private landowners.
What is the City’s plan for replacing the infested trees?
The City is replacing the City-owned trees on streets and in parks that are removed due to EAB infestation. Replacement plantings are mostly native, site-appropriate stock.
Wherever possible, replacement plantings have been started near to concentrations of ash in various park locations and on streets where there is space available to begin this process before the ash trees begin to die.
EAB will certainly diminish Guelph’s urban forest canopy cover, as mature trees will be replaced with much smaller nursery stock, but the intent is to plant enough trees that this setback is temporary. The replacement plantings aim to achieve at least a “break-even” canopy cover, post-EAB, once the planted trees mature.
Ongoing community tree planting efforts, such as those of Ontario Public Interest Research Group (OPIRG) and Trees for Guelph, have been and will continue to be steered, where practical, to contribute to the EAB replanting effort.
Where can I get more information about EAB?
- Canada Food Insepction Agency: Emerald Ash Borer
- Canadian Forest Service: A visual guide to detecting emerald ash borer damage
- Emerald ash borer information
- Ontario Ministry of Natural Resources: Emerald Ash Borer
- What you need to know about the management of EAB: Guidelines for hiring tree care services to manage urban trees
- BioForest Technologies Inc.
For more information
Urban Forestry Field Technologist
Parks and Recreation
519 822-1260 extension 3352