Montreal

Quebec City to cut down 1,000 trees following surge of invasive beetle

Despite efforts to contain the spread of the insect, Quebec City officials have detected the presence of the emerald ash borer in 32 of its 35 neighbourhoods.

Emerald ash borer has now been detected in most downtown neighbourhoods

The invasive beetle, which has few enemies to keep it in check, was first found in Quebec City in 2017 and has since been detected in most of its neighbourhoods. (Minnesota Department of Natural Resources/The Associated Press)

Quebec City workers will be cutting down at least 1,000 trees in parks and along city streets because of an "unexpected" surge in the emerald ash borer population.

Despite its efforts to control the spread of the green beetle, city officials said the insect has now been found in 32 of its 35 neighbourhoods.

Of those, around a dozen are now considered at an "epidemic" level, including Cap-Rouge, Montcalm, Saint-Jean-Baptiste and Vieux-Québec.

Suzanne Verrault, the city's executive committee member responsible for the environment, said the surge is pushing the city to "intensify its efforts" to not "lose control."

The ash borer, which has few natural predators in North America, lays its eggs under tree bark. The larvae then restrict sap circulation, killing mature trees.

The city first discovered the presence of the Asian insect in 2017 and put in place an action plan for 2018-19 to limit its transmission, at a cost of about $1.5 million per year.

But despite those efforts, the growing number of beetles in the area is forcing the city to cut down 1,000 trees by the end of 2019.

Another 1,000 could be cut down in wooded areas by 2020.

'Collision course'

Planted massively in the 1960s and 1970s, the ash tree was widely used in Quebec City urban planning because of its resistance to harsh weather conditions and because it "offered a great canopy," according to Jérôme Picard, an environmental adviser for the city's urban forestry department.

But its abundance has left the city vulnerable to the beetle.

The city neighbourhoods marked in red to be at an 'epidemic stage.' Orange neighbourhoods are 'pre-epidemic' and yellow indicates 'endemic.' (Ville de Québec)

"It's a challenge, but the city intends to replant trees to minimize the impact," said Picard.

The city has been also collaborating on different research projects to find ways to attack the insect, and it has been using a biopesticide called TreeAzin, which attacks the larva.

Another trial test, which hides a mushroom inside a green trap that hangs on a tree branch, has been proven to kill 40 per cent of insects that live nearby.

The technology, being developed by GDG Environnement, has been testing the product in Quebec City for the past two years and hopes to be certified in Canada in 2021.

Robert Lavallée, an entomologist who worked on the prototype, believes cities will have to combine several methods to have a fighting chance against the insect.

Quebec City has also been forced to cut down several old trees in the St. Matthew's cemetery over the past year because of Dutch Elm Disease. (Julia Caron/CBC)

"The objective isn't to eradicate the borer but to bring down its population to tolerable levels," said Lavallée.

"Eradication isn't possible."

Picard said the latest research does provide "hope" the city could one day control the spread.

"But at the end of the day, we are still on a collision course, at low speed," he said.

The city's operations are concentrated on trees growing on public land, but there are 26,000 more on private lots.

The city is asking citizens who live in the hardest-hit neighbourhoods to begin biopesticide treatment and cut down any ash trees that show signs of decline.

With files from Kim Garritty and Radio-Canada's Nahila Bendali

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