City to identify 800 'high value' ash trees fit for insecticide treatment

As part of the city-wide effort to combat the emerald ash borer, city staff are in the process of identifying 800 "high value" ash trees qualified for insecticide treatment, an alternative to tree removal and replacement.

A number has been allocated to each ward based on its ash tree population, said Tami Sadonoja, the city's urban forestry technician.

According to the city's information page on EAB, insecticide will be used on "800 selected high value ash trees." 400 will be identified this year; the remaining will be assigned next year, Sadonoj added.

The notorious pest affects some wards more than others, as ash tree coverage in each ward ranges from 3 to 19 per cent.

Here's a look at the ward-by-ward distribution of 400 ash trees that will go through the insecticide treatment this year.

City staff will also focus on "high-profile areas" like Gore Park, Dundas Driving Park and Gage Park, according to Sadonoj.

EAB is an invasive pest native to Asia. It was first spotted in Ontario in 2002. Hamilton's first infestation was reported in 2009.

Hamilton is home to 23,000 ash trees along city streets and in municipal parks and cemeteries — about 8 per cent of the city's canopy. The number of ash trees in woodlots and natural areas have not been quantified.

Last September, the city adopted a $26.2 million action plan that will gradually chop down Hamilton's ash trees. $100,000 per year will go toward injection treatment, while $1.6 million per cent will go toward removal and replacement. Each injection costs $250 and has to be repeated every other year for the insecticide to be effective.

• Hamilton will chop down all its ash trees over 10 years 

Side effects unknown

Mike McNamara, the city's manager of forestry and horticulture, said the city is only treating a selective number of ash trees so that most of them can be removed and replaced with other species.

"The more species you have, the less effective future pests or diseases have on the trees," he said. "You are not losing an entire area of the tree canopy all at once."

In addition, the long-term effects of the insecticide, TreeAzin, remain unknown, as it was recently approved by the Canadian Food Inspection Agency, according to McNamara.

That worries Maria Pearson, councillor for Ward 10 which has the largest ash tree population and the worst EAB infestation. 61 trees in her ward will be identified and treated.

"These are major injections that go into the trunk of the tree. For me, I question putting anything into the trunk of a living thing," said Pearson, who also owns several ash trees in her backyard.

Injection treatment has already begun in Ward 7 and 8. City staff will continue working with councillors to identify qualifying trees in the remaining ward.

To be a candidate for injection treatment, the ash tree must be 25 centimetres or bigger in diametre at breast height. It also needs to have minimal pest infestation and be free from structural damage.

Although city staff will be following these criteria during the process of identifying salvageable ash trees, Sodonoja said the city welcomes suggestions from residents to consider ash trees on public property.