Canadian Biomass Magazine

Thunder Bay chipping infected trees for biofuel to deal with ‘significant’ emerald ash borer infestation

April 16, 2024
By Sandi Krasowski, Local Journalism Initiative Reporter, The Chronicle-Journal

The City of Thunder Bay’s urban forestry department has discovered a significant emerald ash borer infestation in trees along the Woodward trail corridor, which is consistent with observations made near the rail line.

Urban forestry workers are assessing all the ash trees in this area in preparation for the removal of 115 trees during cooler temperatures before the insect emerges.

Dan Corbett, the urban forester for the City of Thunder Bay, said the city has had an emerald ash borer infestation for a long time, which has developed slower due to the cooler climate.

In dealing with the problem, in 2016, an emerald ash borer strategy was developed through engagement with the academic community and other municipalities.


Part of the strategy involves the constant assessment of the health of the ash trees throughout the city.

“We then conducted strategic removals for trees that either appear to be in decline or are growing in less than optimal growing sites,” Corbett said, adding removals have been ongoing throughout the city since the beetles were discovered.

“The other tool that we have in our toolbox is the trees can be injected with pesticides that may help prevent the tree from being infected by emerald ash borer beetles.”
Corbett said they initially injected 1,700 trees throughout the city and in 2021, the city reduced that number to 850 trees.

“It’s a prophylactic type of treatment for the trees to potentially slow down the infection from other beetles,” he said.

The discovery of the beetles along the Woodward trail was not a surprise and is part of the city’s regular operations.

“These (infected) trees are chipped and then they are brought to the Thunder Bay Pulp and Paper facility to be used as a biofuel to create energy, as opposed to having to spend money to take it to the landfill,” Corbett said. “That allows us to incinerate the chips which incinerates the larva.”

The city has a budget to purchase replacement trees, which will be planted this spring during an Arbor Day tree planting event for the community.

The emerald ash borer is generating a lot of business for local contractors as well.

Vince Rutter of Rutter Urban Forestry has been providing trunk injection pesticide treatments for ash trees since 2016. He said they noticed a recent “explosion” in emerald ash borer populations that is leading to widespread ash tree mortality.

“We expect that trend to continue with this mild winter and for the (emerald ash borer) population to keep growing at a high rate,” he said.

“This was always expected and all ash trees in the city that aren’t protected by pesticide injections will die from (emerald ash borer). We’re recommending that all ash trees are injected annually until the population subsides in a few years. Eventually, the beetles will run out of food because the ash tree will be protected or dead.”

All surviving ash trees will require injections every second year for the foreseeable future.

Rutter added that they too make sure that all tree parts are chipped to kill beetles and help to slow their spread.

Ash trees should not be moved out of the area for use as firewood. The Canada Food Inspection Agency regulates this and prohibits the movement of ash wood from inside the city limits to anywhere else.

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