Oak Wilt is a serious threat to Ontario’s urban and natural forests. The disease is caused by a fungal pathogen that can kill trees within a single year. The disease only affects Oak trees, although this is little consolation when considering the potential tree loss in Ontario!

The disease is not unlike Dutch Elm Disease in many ways. The fungus can be passed from tree to tree systemically through underground roots, as well as on the bodies of beetles that feed on Oak bark and sap. The beetles then transfer the fungus to surrounding trees that are then infected.

So far the spread of Oak Wilt has been limited to the United States and is unconfirmed in Ontario. This does not diminish the threat, however. As we’ve seen with many pest problems in the past, transmission and spread are very fast. In fact, the successes in controlling invasive pests are far fewer than the failures. With Oak Wilt at the border of Southern Ontario now is the time to prepare!

With the above information in mind, most responsible arborists are now discouraging Oak tree pruning in the summer months. Oak tree pruning is being rescheduled to only occur in the dormant season. In this way, the likelihood of transmission by beetles is greatly reduced, as they are not typically present at these times. Trees also commonly release pheromones that attract the beetles to pruning sites. By pruning when beetles are not present this hazard can be reduced. As always, moving firewood is strongly discouraged. Emerald Ash Borer populations exploded in wide locations due to this simple rule not being adhered to. Similarly, proper sanitation of pruning tools is always recommended and can reduce the spread of many pest and disease threats.

Maple Hill Tree Services Inc. is committed to preserving urban forests wherever we can. This includes following industry best practices for disease control, as well as responding to our client’s needs and concerns in the timeliest fashion. Call us today to discuss management plans for your trees.

Please see the attached information sheets for Oak Wilt.