City plans attack on tree-killing oak fungus
Windsor is gearing up to fight a pervasive fungus that is inching closer to the city after killing millions of oak trees in Michigan.
The city has started an awareness and education campaign to stop the spread of oak wilt, which has been discovered on Belle Isle.
“It’s a very significant concern to the province of Ontario and more or less across the country,” said Paul Giroux, Windsor’s manager of Forestry and Natural Areas. “Oak is a very large resource, especially down here in the Windsor-Essex region.”
Oak wilt, caused by a fungus, is a vascular disease that attacks every kind of oak tree.
It was first reported in Michigan in the 1940s and has spread throughout the eastern U.S. Since 2009, the fungus has killed millions of trees in Michigan, including more than 500,000 in Michigan state parks.
According to a report Giroux did for the city’s environment, transportation and public safety standing committee, the disease has not been found in Canada. But in the fall of 2016, its presence was confirmed on Belle Isle State Park, just 600 metres from Windsor’s shores. Oak wilt has spread over 48 acres on Belle Isle, killing more than 112 mature oak trees.
The report states that Michigan is at risk of losing some of its last remaining Shumard oak trees, which are also considered a “species of concern” in Ontario.
To make sure oak wilt doesn’t get a foothold here, the city has partnered with the private consulting firm BioForest, the Canadian Food Inspection Agency and the Invasive Species Centre. They also created a Forest Health program, which uses trained volunteers to survey trees.
Giroux said other plans to stop the disease include increased training for city arborists and giving presentations to utility companies, which prune trees throughout the year.
Giroux stated in his report that if oak wilt does get established here, it has the “potential to drastically change our landscape.” He said there are more than 2,000 oak trees in the city’s street tree inventory alone. If they were infected, removal and replanting would cost more than $2 million.
All of Windsor’s “natural areas” would also be at risk, including the 1,000-acre Ojibway Prairie Complex. “Many of these natural areas contain endangered habitats such as pin and black oak Savanna, unique to all of Canada,” the report states.
Giroux said the fungus can kill a tree in a single season. A sign that a tree has been infected would be leaves dropping to the ground during mid-summer.
“It almost looks like a leaf has been in the toaster,” said Giroux. “The top portion can be brown and the bottom portion could still be green. That’s a very classic symptom of oak wilt.”
The fungus is mainly carried and spread by picnic beetles, which are attracted to sweet smells, including the scent that a wounded or pruned tree gives off. Giroux said oak wilt is also spread to different areas when people transport infected firewood, so the city is asking people not to do that.
“If you’re buying firewood that came from an infected oak tree, you would be transporting this fungus to a new neighbourhood where you could be reinfecting oak trees,” he said.
Giroux added that people also shouldn’t prune oak trees during the growing season between April and August, to avoid attracting picnic beetles.
Another way people can help is to look for signs of oak wilt and report it to the Canadian Food Inspection Agency, the Ministry of Natural Resources and Forestry, the City of Windsor or the Essex Region Conservation Authority.
“Definitely education is going to be the key here, getting the message out to everyday people because oak are prevalent through the city and the county and it’s a very precious resource,” said Giroux.