February 12, 2020

Picture of a huge mature oak tree turning colors in autumn.

Oak trees are incredibly majestic, which is why many people choose to keep them on their properties. However, they require maintenance in order to keep them healthy. This maintenance includes pruning trees in the winter. By pruning your oak trees in the winter, you can reduce the spread of oak wilt. 

What is Oak Wilt?

Oak wilt is a type of fungal disease that affects every type of oak tree (including black oaks, northern pine oaks, and northern red oaks), especially those in Michigan. It’s an incredibly deadly disease that can kill an oak tree within just a few weeks of the initial infection. The disease spreads from one tree to another via underground root contact. This occurs when sap-feeding beetles carrying the spores of the fungal disease move from one tree to another. Common symptoms include:

  • The discoloration of the oak’s leaves.
  • The leaves begin wilting and curling.
  • The oak’s leaves begin dropping in the summer.
  • Suckering at the oak’s base.
  • Dead crowns.

Unfortunately, there’s not much you can do once an oak tree has been infected, which is why prevention is so important.

How do You Prevent Oak Wilt?

The following are a few steps you can take to prevent oak wilt from occurring:

  • Know when to prune your oak trees – Pruning oak trees in winter is a better idea than doing so in the spring. Avoid pruning your oak trees between April 15 and October 1. This is the time of year when beetles are most active. If you prune your trees at this time, the beetles will be attracted to the fresh wounds of your tree branches and will be more likely to spread the disease. 
  • Cover wounds if you have to prune during the high-risk period – If for some reason you are forced to prune your oak trees between April 15 and October 1, then make sure that you use a latex-based paint or a tree-wound paint in order to cover the wounds where you pruned the tree. For example, you might have to prune your oak trees if they experienced damage during a particularly bad storm. 
  • Always disinfect your pruning tools – Use an all-purpose household disinfectant, such as a water and bleach solution, to clean your pruning tools so that you don’t spread the disease if one of the oak trees you pruned happened to be infected without you realizing it. 
  • Avoid moving your firewood – Oak trees are a great source of firewood; however, if you have a pile of firewood that you think might be infected by oak wilt, then do not move it. Moving it can spread the spores, which can increase the risk of infecting your other trees. Instead, use a tarp to cover the firewood and to keep beetles away. Keep it covered until next fall.

If you spot any symptoms of oak wilt on your property’s oak trees and suspect that they might be infected, then you need to have them professionally removed to ensure that they do not spread the disease further. Be sure to contact us at Twin Oaks Landscape in Ann Arbor, MI, for help dealing with any oak trees that you think may have been infected with oak wilt today. We can assess your trees and prune them when they are least likely to be affected by oak wilt.