Toronto Star column – published April 6, 2013
The clock is ticking on the ash trees in the GTA.
The ‘delete’ button was pressed a few years ago and within the next 3 to 5 years all of the untreated ash will be history. The emerald ash borer (EAB) has crept up here from the mid western States, arriving there about 15 years ago from Asia. It begins its nasty work very quickly, gnawing its way under the bark of ash [all Fraxinus species] until they are dead.
In Toronto, our tree canopy consists of about 8% ash; most of the 905 area is between 8 and 10% while in Ottawa the total number of ash represent over 20%. Ouch! No matter where you live in southern Ontario, EAB is one big pain.
It was a year ago that I first wrote about the emerald ash borer problem in the Star. At the time many readers were shocked to learn the extent and the severity of the infestation. Many were also keen to learn more about the treatment of ash and the control methods for the borer. It is time for an update.
What Has Changed in a Year?
Over the span of the past year I have been impressed by the changes that have occurred in many municipalities with regards to the EAB problem. I have no doubts that this is due to the increased attention that the issue has received here in the press, the resulting rise in interest on the part of concerned citizens, municipal employees responsible for urban trees, and the fact that more politicians have taken a keen interest.
Nevertheless there are many questions that need to be answered. Here are the essential ones:
How pervasive is the emerald ash borer?
All ash trees are ensured of being attacked. There are 22 species in Southern Ontario but the most common are white and black ash. It is expected that EAB will be most active in the GTA over the next 3 to 5 years at which time it is anticipated that the problem insects will have moved on and/or died out due to a lack of food sources.
How effective is the treatment for EAB [TreeAzin]?
Unlike the Dutch Elm Disease that killed virtually all of the American Elm that lined our streets in the 60’s and early 70’s, EAB can be controlled using TreeAzin, a ‘biologically based’ liquid that is injected into the tree by licensed professionals. TreeAzin is a derivative of the Neem tree, a native of south/east Asia. Neem is popular as a plant shine and used for control of the lily beetle on oriental lilies.
How much does it cost and how often is it applied?
The cost of treatment for an average ‘mature’ sized ash of 40 cm in diameter, measured at 1.2 meters high, is between $250 and $300 per tree/per treatment. The cost has come down over the last year by about 25%.
How and when is it applied?
It is injected into the tree, near its base any time from June through August. The tree ‘takes the product up’ through the rise in sap that occurs naturally. I recommend that you treat ash before you see damage as the tree is best able to take up the Tree Azin product while healthy. Under normal circumstances a tree will need to be treated every 2 years, three or four times for effective control. Total cost between $800 and $1,200. Note that cutting and replacing a mature ash will run you about the same amount of money, perhaps more.
How effective is it in the long term?
While TreeAzin has only been registered with Health Canada’s Pest Management Regulatory Agency [like all registered pesticides] for less than 10 years, test treatments have indicated that permanent control of EAB is possible with the recommended 3 or 4 applications. According to Joe Meating, the president of BioForest, the Canadian company that produces and distributes TreeAzin, it is believed “that the ash borer will have moved on or died out after the 3rd or 4th treatment [6 to 8 years] as fewer trees will be alive to host the insect.”
How do I know that my tree is a good candidate for treatment?
If the tree in question is growing on private land, I recommend that you get a professional opinion. For a list of recommended TreeAzin applicators go to www.yourleaf.org and check out the list under the Resources tab.
If the tree is growing on municipal property [like a boulevard tree that may be located at the front of your house or on your street], I recommend that you contact the urban tree or parks department in your municipality.
If I wish to have an ash tree treated that is growing on public land, how do I go about this?
As of today every municipality in the GTA and Ottawa has established policy regarding this issue. They have put money aside in their budgets for the treatment of valuable ash and for removal and replacement in the case of the untreated specimens on public land.
Every municipality is approaching the issue differently and with various degrees of aggression. The most ambitious treatment program is in Oakville where the goal is to save more than 80% of the ash tree canopy. Others municipalities are shooting for a ‘save rate’ of less than 5% of the trees on public property. There is a clear disparage here.
What kind of tree should I consider replacing ash with?
If we have learned anything at all from this exercise, it is this: our urban forest will benefit most and serve future generations better with greater species diversification. So the answer is not as straightforward as, ‘plant sugar maples’ since your situation may be more appropriate for other species.
I do encourage you to consider making a selection from the broad selection of native trees available. I do not advocate that a native tree is suitable for every situation but we definitely need to plant more than we have in the past. An excellent list of native trees and flowering shrubs is offered on the LEAF website [ http://www.yourleaf.org/species-available].
A visit to your local garden centre can be useful. Talk to a qualified professional about your location, exposure to sun, soil quality, drainage, and your own wishes to make an informed decision.
How do we avoid another problem like this in future?
I can almost guarantee that there will be another pest or disease that will wreak havoc on our tree population in future. History tells us that we should be on the lookout for it.
My answer to this question is the same answer as the last one. Diversification.
A good defence is a good offence. Or something like that.
Where do I go for more information?
The city of Toronto has published an excellent hand book titled ‘Emerald Ash Borer’. You can access it online at http://www.toronto.ca/trees/eab.htm. Whether you live in Toronto or not, the information is useful.
If you live in another municipality, call city hall or access their website. Most are working hard on their communication programs now.
I encourage you to talk with your local municipal councillor and to your neighbours. Smart people are rallying around this issue to raise awareness and money to save whole streets of ash from the chop-chop. This is your chance to lead and make a very big difference.
Question of the Week
Q/ Skunks are digging up my lawn every night. How do I stop the damage?
A/ Raccoons and skunks are digging in lawns to feed on grubs. Once the soil temperature is above 10oC you can apply beneficial nematodes to control the grub population. I use Green Earth Grub Busters.