Marsh’s ash trees under attack by invasive pest

Mississauga News
April 29, 2014
By Chris Clay

Clarkson’s Diane Damario has enjoyed visiting Rattray Marsh for a number of years and always wanted to give back in some fashion.

Now that the marsh’s 2,200 ash trees are under serious threat from the invasive emerald ash borer, Damario thinks she might have found how she can help.

“My family and I visit Rattray Marsh frequently and I think it’s quite amazing that when you go into the marsh you can’t see any signs of the city around it,” said Damario. “I don’t think I had quite realized the extent of the problem. It will be kind of sad to see such a large canopy disappear (if nothing is done).”

Damario was one of about two dozen people who attended a meeting last night, organized by Credit Valley Conservation to discuss the threat the borer poses to the marsh’s trees. They’ve started a campaign to protect the trees and replant new ones and the CVC hopes to raise $25,000 from the community for this year’s efforts.

Damario said she’s ready to help.

“I’ve always intended to donate to the CVC for quite some time but never got around to it,” she said. “This is an opportunity to do something now for all the years we’ve enjoyed the marsh.”

It was a sobering message for those who attended the meeting: The marsh has just under 2,200 ash trees, which comprise about 80 per cent of Rattray’s tree canopy, and only about 97 can be saved as the rest are too far gone from borer damage.

CVC officials told the crowd the borers will kill off the remaining ash trees on the 95-acre site with nearly 100 per cent efficiency.

Trees can be saved if they’re injected with TreeAzin, a compound derived from the seeds of the neem tree. The average cost is about $200 per treatment and the trees would need injections for two consecutive years and every two years after.

Dave Wiley, CVC’s forestry foreman, said they won’t replant ash trees and are looking at other types native to the area such as the sugar maple or hickory.

Rattray Marsh is one of the CVC’s most popular areas with about 3.3 kilometres in trails and more than 300,000 visitors a year. About 2.2 km of the trails have ash trees along them and they will pose a safety concern when they die.

Kevin De Mille, an EAB invasive species technician with the CVC, said the borer damage causes the tree’s roots to fail first and then the whole tree topples over.

The CVC isn’t alone in dealing with the issue, as the City of Mississauga has a 10-year, $51-million plan to address the pests that are ravaging ash trees on municipal property.

The municipality first became aware of the pests in 2008 when they started popping up on private property. In 2010, the City found the borers had spread to trees on municipal property.

The borer was first found in Ontario in Windsor back in 2005 and has been making its way steadily across the province ever since.

Adult borers lay eggs in bark crevices in early summer, which hatch after a few weeks. The larvae then chew the outer bark and feed on the inner bark, creating tunnels that impact the flow of water and nutrients throughout the trunk.

Telltale signs of a borer infestation include loss of leaves, small branches and shoots sprouting from the trunk and loss of bark as well as increased presence of woodpeckers feeding. Infestation can kill a tree within months.

Clarkson’s Gerry Ruygrok also attended the meeting, primarily because he has a large ash tree on his property. However, he was interested with what he heard and agrees with the CVC’s philosophy of trying to retain the natural beauty and ecosystem of Rattray Marsh.

The City and CVC encourage residents to inspect their ash trees and contact a certified arborist if they suspect a borer infestation.