All of the ash trees in Toronto will be dead or dying by 2017 so the city will begin removal of such trees from streets and parks at the end of June.
"The city of Toronto is under attack and regrettably we're helpless in the face of this invasion," said Councillor Norm Kelly (Ward 40, Scarborough Agincourt), chair of the Parks and Environment Committee.
The infestation of a beetle known as the emerald ash borer disrupts the flow water and nutrients in the trees, starving them to death.
The pest, which is native to East Asia, was first found in Windsor, Ontario in 2002. The Canadian Food Inspection Agency categorizes it, as "highly destructive," and has confirmed infestations throughout the east, north and western parts of the city with particular presence in Scarborough.
Officials have given up on eradicating the invasive pest and have focused efforts on managing impact. This includes surveys of infestation levels, an inventory of Toronto's ash trees, removal of trees and pesticide treatment in some cases.
Certain high value trees in parks and on golf courses will be treated with a pesticide known has TreeAzin™. It is the only product available in Canada that has shown to be effective in keeping the ash trees alive. Treatment with the pesticide is required every two years and each tree requires up to five treatments. The pesticide is only effective on low-level infestations.
It will cost the city between $60- and $70-million over the next 10 years to remove city-owned trees, said Mr. Kelly. He called it "an unexpected and high cost to the public treasury" and one that is unavoidable. The average cost for the city to replace an individual ash tree 35 centimetres in diameters is $751. It will cost them about $250 to replace each tree with a new species.
There are an estimated 860,000 ash trees in Toronto. "Unfortunately it's our belief that all of these trees will be killed within the next 10 years," said Mr. Kelly.
Paul Bolan, vice-president of Bioforest Techonologies Inc. – the company that helped develop TreeAzin™ – disagrees with the city's removal plan. He says the science has changed and the city's strategy is out of date. "Management options available before 2009 are to a large degree irrelevant," he said.
Sixty per cent of the city's ash trees are privately owned.
Any property owner with an ash tree on his or her property will be responsible for its treatment and eventual removal if it dies. Property owners are not required to remove healthy ash trees, but once one dies and begins to decay, which seems certain based on accounts by city officials, the owner must remove the tree before it becomes a hazard.
Removal of a tree can cost a private citizen anywhere from $750-$1500. TreeAzin™ on average costs about $150-$225 per a treatment for a tree about 30 centimetres in diameter.
The city will be holding three public information sessions about the situation on June 20, 21, and 27 from 7-9 p.m.