The city is trying out a new insecticide to save ash trees such as this in Jack Purcell Park from the dreaded emerald ash borer.
The city has a new lethal weapon against the wood boring pests ravaging the city’s ash trees, but it could hold environmental implications, according to the federal department of natural resources.
Confidor is an injection insecticide that Ottawa and Toronto are testing to combat the rapidly spreading infestation of the emerald ash borer across Ontario. Previously used in the U.S. and approved by Health Canada last year, the insecticide will be used on a small number of trees. The new chemical will be compared on a trial basis with the city’s current tree injection of choice, TreeAzin.
“This trial program will allow researchers to assess the effectiveness of this insecticide and the injection system on ash trees in Ontario,” says Nichole Hoover-Bienasz, assistant to River Coun. Maria McRae, chair of the city’s environment committee. “The city is making a concerted effort to help researchers find solutions or methods to help preserve ash trees.”
McRae and Mayor Jim Watson revealed the addition to the arsenal two weeks ago at a home in South Ottawa.
The city’s other strategies against EAB include planting other species of trees and removing highly infested ones. Last spring, the city planted 1,267 trees in streets and parks where ash trees are present, says Bienasz. An additional 2,700 trees will be planted this fall, she says.
The pest arrived in North America on improperly treated wood imported from Asia in the early 2000s. It exclusively attacks ash trees by burrowing underneath its bark, inhibiting its ability to absorb nutrients and take in water. The damage is exclusively done by the insect’s larvae form, which creates tunnels when feeding in tree trunks, branches and roots.
“The synthetic insecticide Confidor is highly toxic to emerald ash borer and is likely to be very effective assuming a proper formulation that can be taken up by the tree, Michelle Viau, a department of natural resources official, said in an email.
While Confidor may be more effective against the borer, the department has raised concerns that it may have a longer-lasting environmental impact because trees retain the insecticide’s active ingredient for a prolonged period of time.
This can go on to harm non-target species and inhibit leaves from decomposing in the fall, an essential source of nutrients in soil. TreeAzin’s active ingredients, meanwhile, are natural compounds absorbed by trees.
“With its demonstrable efficacy and favourable environmental (benefits), TreeAzin would appear particularly well suited to use in urban or sensitive ecological environments,” the department spokeswoman said.
Ash trees comprise 25 per cent of the city’s tree population. In Centretown, pockets of ash trees grow in St. Luke’s Park, Minto Park and on the grounds of the Jack Purcell Community Centre.
The alien beetle invasion infested several of the ash trees found at Jack Purcell. In response, the city and the Jack Purcell Park Project planted five maple trees on the property in June 2011.
Centretown residents use the revamped dog park at Jack Purcell Park, still shrouded by ash trees.
“This is a gorgeous park and the ash trees here are a big part of that,” says Sam Lafleur, a frequent visitor of the park with her beagle-pug mix, Koby.“These trees need to be protected – at any cost,” she says.