Many people contact us because they’ve already removed one or more ash trees in their yard and want to replace them with new native species through our Backyard Tree Planting Program. While we certainly encourage everyone who has lost an ash tree due to EAB infestation to plant a new tree in its place, we want to make sure that all homeowners know there is an alternative to removal available. Treatment with TreeAzin™ Systemic Insecticide may be able to save your ash tree.
TreeAzin™ is produced from extracts of Neem tree seeds, and is the only effective pesticide available to control EAB in Canada at the present time. It works by being injected under the bark, and is drawn upwards with the flow of water and nutrients inside of the tree. It will kill EAB larvae that are feeding on conductive tissues within the tree and will also reduce the adult female’s fertility and egg viability when it feeds on the leaves of the tree. Injections are carried out in early summer, and treatment needs to be repeated every two years to remain effective (as long as the Borer remains in the area).
According to the manufacturer’s website, in the year of treatment, 95% of EAB larvae are killed, significantly fewer eggs are laid, and of those that are laid, 98% are not viable. In the following year, larvae hatching from the few viable eggs that are laid will not complete development, and the length and number of galleries that larvae have created from feeding underneath the bark of the tree will be fewer and shorter in length when compared to those in ash trees left untreated.
Because the insecticide is injected under the tree’s bark rather than applied externally, the treatment does not present a health risk to those carrying out the injections or to the surrounding environment. Studies show that TreeAzin™ has low toxicity to mammals, birds, bees and other non-target species and has low-to-moderate persistence in waters, soils and foliage. It is registered as a class 4 pesticide, which means it is the "least hazardous that is commercial".
There are many reasons to consider treating your ash tree. There are approximately 860,000 ash trees in the City of Toronto and an estimated 2,800,000 mature ash trees growing in York Region. All are at risk of infestation, and if left untreated, most will succumb to the pest. This will create huge gaps in our urban forest canopy, a vital resource that provides shade, sequesters carbon and conserves energy by shading our homes. It is also important to remember that the larger a tree grows, the more benefits it provides. It will take years for a newly planted tree to fully take the place of a mature ash in the canopy and offer maximum benefits to our urban environment.
In addition, it may be financially beneficial for you to treat your tree rather than have it removed. The cost of treatment ranges depending on factors such as size, health and location of the ash tree. We recommend getting quotes from at least three different registered service providers before making any decisions about who to hire. In some cases, paying for treatment every other year while EAB populations persist in your area may be more affordable than the costs of removal, disposal and replanting. In addition, rather than paying one lump sum for removal, treatment allows you to spread out the cost of managing EAB over a number of years.
Find more information about the Emerald Ash Borer here. Learn more about TreeAzin™ and to find out if it is the right option for your ash tree here.