What Is Killing Oak Trees In Michigan?

Michigan’s oak trees are under attack! The culprit: oak wilt. This disease was first reported in our state in the 1970s, though it’s been elsewhere in the country since the early 1900s. This disease is difficult to eradicate as it spreads in several ways. If left untreated, it could result in the full removal of the tree. Thankfully, proactive tree care can rescue your oaks – but it’s important to act quickly!

Oak Wilt In Michigan

Everything You Need To Know

Oak wilt is now the leading disease that kills oak trees in our state. It’s moved across our state at an alarming rate. April – July is the period when your oak trees are most at risk.

Why Is Oak Wilt Bad

Oak wilt will quickly kill off trees in the red oak group – that’s oaks with pointed leaf margins. Oaks in the white group – those with round leaf margins – are still affected, but the disease seems to progress more slowly for them. For some reason, white oaks seem to have a resistance and can compartmentalize the oak wilt fungus to still adequately transport water. Aside from killing the tree, oak wilt is so disastrous because many activities that would normally not harm your tree can let oak wilt in. These activities can include pruning, trimming, hanging a tire swing, or nailing a birdhouse into the trunk. Basically, anything that opens up a wound in the trunk could cause the tree to get infected. Oak wilt has devasted entire ecosystems across the country.

How Does Oak Wilt Spread

Here’s the crux of the issue. Oak wilt actually has multiple means of spreading, which is one of the reasons it’s so hard to treat.


Local spread of oak wilt occurs when the fungus travels through root grafts, i.e., the interconnected roots of infected and healthy trees. One way to prevent this type of spread is by creating barriers like trenching or vibratory plows. However, this is not always practical, especially in urban or residential areas.


Picnic beetles are attracted to mycelial mats produced on trees killed by oak wilt. Beetles are drawn by the odor and pick up fungal spores, which they can spread to healthy trees. These beetles are also attracted to sap produced by fresh wounds on live oak trees. If beetles are contaminated with oak wilt spores, when they visit a fresh wound to feed on sap, those spores can seep into the tree via the sap.


If you’re an avid camper or outdoor enthusiast, you’ve probably seen signs warning not to transport firewood outside of a local area. This is just one of the diseases that you can inadvertently spread by doing so. Firewood spreads oak wilt because of those mycelial mats. When you transport firewood, you are potentially bringing those infected mats to a new area.

5 Signs that Your Tree Has Oak Wilt

  • Yellow Leaves. Have you noticed yellow leaves with greenish-colored veins on your oak tree?
  • Foliage Loss. Oak trees are bound to lose at least some of their foliage, especially when the cool fall and winter weather arrives. But if this is happening well before fall, it could be an indicator of oak wilt.
  • Decaying Bark.
  • Powdery Mildew.
  • Rotted Roots.

Don’t Trim Oak Trees

If you think your oak tree is diseased, your first thought might be to amputate the infected branches. While this can help slow the disease in the early stages, doing so can actually open up your trees to many infections. DO NOT prune, trim, or cause any injury to your trees between April and July. This is when oak trees are most vulnerable to oak wilt. We actually just passed the cutoff date of July 15, so if you need tree trimming or pruning, call PPM Tree Service & Arbor Care. We have the equipment and knowledge to get the job done without causing further problems for your tree.

How Oak Wilt Is Treated

If caught early, disrupting root grafts and removing branches of an infected tree is possible. If the damage is extensive, unfortunately, the tree may have to be removed. In this circumstance, PPM can help you remove the tree and the stump so there are no infected remnants left that might spread to other oaks in the area.

Find Oak Wilt Treatment Near Livonia

If you suspect your oak tree(s) may be suffering from oak wilt, don’t hesitate to contact PPM Tree Service & Arbor Care. The sooner we can address it, the less likely you’ll have to remove your tree. Often, we can prune the infected areas and take measures to stop the spread via the roots. But you must act quickly! Give us a call at (877) 454-8733, or leave us a message online. If you’re curious about other tree care topics, be sure to check out our blog page, where we post articles twice a month. You can also like us on Facebook, follow us on Twitter, and browse our Pinterest boards to learn more.

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