Thunder Bay

Emerald ash borer report to go before council

Thunder Bay City Council will have several options to consider when it comes to addressing the appearance of emerald ash borers in the city.

Administration recommends treating affected trees as much as possible

The city of Thunder Bay has long anticipated the arrival of the invasive emerald ash borer. (David Cappaert/Michigan State University)

Thunder Bay City Council will have several options to consider when it comes to addressing the appearance of emerald ash borers in the city.

The invasive insect, which targets ash trees, was discovered in Thunder Bay in late June.

On July 18, council will receive a report with recommendations on how to deal with the insects.

"We're going to recommend a combination of removals and treatment," said Shelley Vescio, city forester. "We have beautiful ash trees in our city, and each of them is going to be affected by it."

"We'll be recommending the highest number that we can afford to treat," she said. "We'll still have to see if we can actually find that many to treat, because they have to be eligible trees, meaning they have to be greater than 20 centimetres in diameter, and they have to be in good form and excellent health."

Tricky to spot

It may be tricky to spot emerald ash borer-affected trees in the city. Symptoms, Vescio said, don't show up for a couple of years.

If a tree can be treated before symptoms appear, there's a likelihood the treatments will be successful.

However, Vescio said, many of the city's ash trees have already had years of defoliation due to a disease called anthracnose. The symptoms of anthracnose look similar to those caused by emerald ash borers.

"When we look at trees that might have a level of defoliation, we don't think we're looking at emerald ash borer, we think we're looking at anthracnose," she said. "So it's hard to know if we should be treating those trees or not."

"It's not going to be easy," Vescio said. "We're going to have to look at each tree."

The city will also host information sessions later this month aimed at helping residents spot infected ash trees on private property.

So far, Vescio said, the only ash trees found to have emerald ash borers are located in a one-block radius at Memorial Avenue and Fourth Avenue.

Whatever treatment option council approves, Vescio said it will cost the city millions of dollars over the next decade.

"We're looking at about a 10-12 year life cycle," she said. "When we remove [trees], another thing we're going to recommend is we replace. We don't just remove and not replace."

"There isn't an option that has no cost," she said. "If we didn't treat, if we just let it run its course, that would be the most expensive cost. Actually treating trees over that 10-year period — because you have to every second year — is actually less expensive than removing, replacing, stump grinding, wood disposal, all of that stuff."


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