Early insecticide treatment best way to save ash trees from beetle, expert says

Trees that aren't inoculated with pesticide will be as good as gone once an invasive beetle arrives in Fredericton, a Mississauga city official says.

The emerald ash borer, an invasive beetle that has destroyed millions of ash trees in parts of North America, was detected in Edmundston last year.

Jessica Wiley, manager of forestry for the City of Mississauga, spoke at a committee meeting in Fredericton on Thursday.

She said officials in New Brunswick's capital need to be ready for the tiny insect. 

"It really isn't stoppable as long as there's a viable food source," she said. "You guys have beautiful ash trees, and I would highly recommend, if you want to preserve them, now is the time to get some sort of plan together."   

The emerald ash borer was identified in Mississauga in 2008, and the city's plan to inoculate wasn't approved until 2012.

By then city officials were dealing with 23,000 street trees impacted by the emerald ash borer. That doesn't include parks and wooded areas. Some of those trees died within the year.

"I would highly suggest to anyone who's seeing it coming … to deal with it in advance of it getting here," she said.

Native to Asia, the emerald ash borer was first detected in 2002, according to Natural Resources Canada.

"Emerald ash borer came at us in pretty much every direction," Wiley said.

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Ash trees have limited resistance to stave off the insects, which can kill trees within one to four years of infestation.

Over 10 years, it cost the City of Mississauga $51 million to inoculate 20,000 street trees. Some trees were injected with pesticide multiple years in a row, while the city was "in the thick of it," Wiley said.

"At that point, we knew the insect was there and we knew injecting when the insect is in the tree, it isn't a silver bullet. It won't fix it.

"It needs to be in the tree before the insect gets there to be effective."

Cost of doing nothing is higher

But she said the cost of doing nothing would be "substantially more" expensive because it could include tree removal and replacement and dealing with wood waste.

"We're happy with how we chose to deal with our ash," she said.  

Today, the trees are assessed every year and injected every other year.

"We're seven years, and I can honestly say that there's trees that still look healthy today, which I think is very promising," she said.

Fredericton has about 10,000 ash trees in Odell Park alone and about 2,400 along city streets. The numbers don't include ash trees in other city-owned parks or on private property. 

On their own, the emerald ash borer only travels about 400 to 700 metres a year, but with people moving firewood from province to province, the ash borer can travel much farther. 

The City of Fredericton has been setting up traps to identify where and how many beetles there might be in the city.