Towering over Lindsay Burtenshaw on the Ravine Road Trail is one of the few ash trees in Hamilton with a hope of survival.

It shoots straight up and spreads out to shade the ground below. As you look skyward, you can see its crown brush against the trees around it, many of them also brilliant green ash trees.

But this single fortunate ash has an advantage. It has been vaccinated against the emerald ash borer.

Five years from now, there will be a lot fewer ash trees on Hamilton trails, says Burtenshaw, a terrestrial ecologist with the Royal Botanical Gardens (RBG). The RBG injected 21 trees this summer, but thousands more on its properties will likely die from the invasive pest.

"Ash trees make up a big part of our forests in Ontario," she said. "They're unique in that they grow very straight and are a very pleasant tree to look at."

That will not be the case for long.

Council will decide

The emerald ash borer was first spotted in Hamilton in 2009. On Sept. 6, the city's general issues committee will vote on a broad strategy that could involve injecting some trees with the pesticide TreeAzin and chopping down many others.

There are about 11,000 ash trees lining the city's streets, said Mike McNamara, manager of forestry and horticulture. There are another 12,000 in Hamilton parks.

'It's one of the most devastating pests in North America.'—Brian Hamilton, Canadian Food Inspection Agency

That number doesn't include woodlots or the rural areas of Hamilton, he said. It also doesn't count the thousands of trees on private property.

"This is a huge problem," McNamara said. "It is for all municipalities.

"We're looking at asking (council) to support different options that range from proactive to reactive management plans."

First seen in Windsor

The emerald ash borer arrived in Ontario in 2002, brought here on wood imported from eastern Asia. It first appeared when people at the University of Windsor started noticing dead trees around campus, said Brian Hamilton, area forestry specialist with the Canadian Food Inspection Agency (CFIA).

The insect is common in countries such as China, Japan and Mongolia. But in Ontario, it has no natural predator, so it spread out of control, Hamilton said.

First, the CFIA tried to cut an ash-free zone through Essex County to stop the borer from spreading to the rest of Ontario. But it continued, likely from people transporting firewood, he said.

It crept across southern Ontario. It ate through sensitive Carolinian forest, which in some areas is 30 per cent ash. Now the borer has been found as far as Ottawa and eastern Ontario.

It's killed millions of trees in Ontario. In North America, "that number could easily be a billion," Hamilton said. "It's one of the most devastating pests in North America."

Ground zero

Many municipalities are chopping down their dead or dying ash trees and replanting with native Carolinian species. This includes Kentucky coffee trees, tulip trees and different varieties of oak.

Affected municipalities are quarantine zones when it comes to moving wood in and out, Hamilton said.

'The borer will go until everything is pretty much gone.'—Bill Roesel, manager of forestry and horticulture, City of Windsor

There is no money from other levels of government to help deal with the borer, McNamara said. He wouldn't say ahead of the report how much he thinks it'll cost Hamilton.

But Bill Roesel, Windsor's manager of forestry and horticulture said it cost his city $4.6 million over six years.

"We were ground zero here," he said. "It was very quickly determined by the CFIA that there was no way to stop it."

Fly-by-night operations

Municipalities who haven't faced the full impact of the borer's presence cannot overestimate its impact, Roesel said. Since it takes a couple of years for a tree to die, it doesn't look like a problem at first.

Then suddenly, there is massive tree removal, he said. One Windsor neighbourhood lost 40 trees in three blocks.

"The borer will go until everything is pretty much gone."

Hamilton can expect fly-by-night tree removal businesses to appear, he said.

"There were a lot of people who didn't know what they were doing but they were looking for work, so they'd go around with a pick up truck and a chainsaw," he said. "There were a lot of weekend warriors. Obviously, you want to make sure any company you hire has its own insurance."

General issues committee meeting

When: 9:30 a.m., Sept. 6

Where: City hall council chambers

As for injection, it protects trees for two years before they need to be injected again, Burtenshaw said. It cost RBG an average of $389 per tree, for a total of $7,780 spent on tree injections this year.

Tree removal will cost the RBG an estimated $177,000, she said. Replacing those trees with new plantings will cost another $50,000.

Hope for the future

For the RBG, ash represents about 15 per cent of the mature trees in its 350 hectares of forest. About 80 per cent of the seedlings sprouting in the forest's undergrowth are ash.

Once the borer spreads fully, "the holes in the canopy will show up along our trails," she said. "You're going to see a lot more dying trees."

Burtenshaw recommends people keep an eye on their trees. Dead ash trees must be removed before they come a hazard, she said.

But as for the future of ash, she's not giving up hope.

"Don't rule out a predator in the future that might start eating the ash borer," she said. "There always might be an ash tree that's resistant and we can study that tree and find out.

"Don't rule out science. They might discover something that can find a way to control the ash borer. But also, be prepared."