Local conservation authority watching for oak wilt in Lambton


Alex Kurial
Local Journalism Initiative

Canadian conservation officials are on the lookout for a fungus that has travelled through Michigan and threatens to cross the international border.
The fungus is known as oak wilt, and is carried by sap beetles. It has been recorded as close as Belle Isle, a small island on the American side of the Detroit River between Detroit and Windsor. It is an extremely deadly fungus capable of killing a full grown red oak tree in just two weeks. White oak trees last longer but ultimately meet the same fate.
Tim Payne, manager of forestry with the St. Clair Region Conservation Authority, is part of a team working to see if the fungus has made the leap.
Working with the Ministry of Natural Resources and Forestry, Payne and his team have just finished conducting a series of tests throughout St. Clair Township to see if local beetles are carrying the fungus. It’s the second straight year the conservation authority has conducted the tests after seeing the close proximity of the threat. They use a pair of methods to gather results.
The first is a ‘trapping’ process where a pheromone is used to attract the sap beetles, also known as picnic beetles. The other method is known as ‘wounding’. A small hole in the tree is created to draw sap before being plugged back up. Payne and his team then place a pheromone lure nearby to see if the beetles were more attracted to the natural sap or the artificial bait.
Payne says valuable information is gained from the tests. Most importantly they are able to see if any of the beetles are carrying the fungus, which would indicate it has made the jump into Canada. Payne says that the tests also show when the beetles are most active during the year, and what attracts them to oak trees.
Despite starting testing last year though, the results are still not in. Payne says the ministry lab the beetles are sent to conducts tests on samples from across the province on a variety of topics, and wait times are long. The COVID-19 outbreak has also slowed things down. But Payne hopes that the results should arrive any week now.
Payne also outlined many preventative steps that can be taken to halt oak wilt in the first place. One is to give proper spacing to oak trees. If two or more trees are close, one infected tree can give oak wilt to all surrounding oak trees through their interconnected roots. Even if an oak tree is cut down, beetles feeding on sap from the stump can transfer the fungus to its neighbors via their grafted roots.
Proper timing of tree care is also important. Payne says try and do your pruning or harvesting in the fall and winter when less sap is being produced. Springtime is the worst time to treat oak trees as sap flows throughout the tree as they start to sprout their leaves. Payne also says a special paint can be used to cover up nicks or broken branches from storms or maintenance work.
So far no evidence of oak wilt has been seen north of the border. Payne says Ontario faces the greatest risk because of the border with Michigan, where the fungus has been a serious problem. But he is optimistic that through good forest practices, and data gained from two years of testing, that Canada can deny entry to this unwelcome visitor.