Trees enhance the appearance of our streets and increase the market value of our properties. They function as air purifiers, air conditioners and noise barriers, while helping to control erosion. That’s why we’ve always planted them in urban areas. Chosen for their robustness and rapid growth, ash trees have nevertheless suffered numerous assaults in recent years by emerald ash borers, an invasive plant parasite. Luckily, the battle is a little fairer these days, chiefly thanks to preventive measures, including pruning and treatment with TreeAzin.
A discreet, but destructive enemy
Millions of ash trees have died since the emerald ash borer, originally from Asia, arrived in North America during the nineties. In Canada, this little metallic green insect was first detected in Ontario in 2002. Over the following years, it made its way through the province of Quebec: Montérégie (2008), Montreal and Gatineau (2011), Longueuil (2012), Terrebonne (2013) and the Quebec City area (2017). With no natural predators and a predilection for all the species of ash that grow here, the emerald ash borer has been particularly devastating in Montreal, where one out of every five trees planted on public land has been an ash. Since 2016, the battle against this beetle has cost the city $20 million.
The presence of the emerald ash borer is insidious. You won’t see swarms of them devouring leaves; all it takes are a few individuals to kill a tree. In fact, the larvae (whitish worms about 3 cm in length) cause most of the damage, digging tunnels as they feed underneath the bark of the tree, interfering with the circulation of water and nutrients. Once infested, the ash tree begins irreversibly losing its leaves, starting at the top. After a year, it’s generally condemned to death. That’s why it’s so important to begin treatment as soon as the pest is detected. Curved grooves beneath the bark and D-shaped exit holes on the surface indicate the presence of emerald ash borer.
There’s an ecological weapon against emerald ash borer
Cutting off the infested branches will give the tree a reprieve. But to really increase its chances of survival, it’s necessary to attack the insects, themselves. Four products have been approved by the Canadian Pest Management Regulatory Agency (PMRA) to combat the emerald ash borer. The one that has proven most effective is TreeAzin, a systemic insecticide formulated with azadirachtin. A TreeAzin treatment works over a two-year period. Once injected into the tree, the product is absorbed and diffused throughout the tissues. The active ingredient, azadirachtin (an extract of the neem seed), inhibits the development of the larvae. As a result, the emerald ash borer population is controlled, as fewer of the drilling beetles reach adulthood. It’s worth noting that azadirachtin (commonly called neem oil) has no significant negative impact on other insects and pollinators and it also breaks down quickly in the environment.
To learn more about preventive tree trimming, as well as other possible treatments for emerald ash borer, please don’t hesitate to contact one of our experts in tree health. At Emondage SBP, we’re looking toward the future.