Oak Wilt in Madison, WI: What Every Homeowner Should Know

If you have oak trees in your yard, you need to know about oak wilt. It is one of the worst tree diseases in Wisconsin. The good news? If you catch it early, you can save your trees.

What Is Oak Wilt?

Oak wilt is a sickness caused by a fungus. It gets inside the tree and blocks the flow of water from the roots to the leaves. When that happens, the tree starts to die from the top down.

Red oaks get it the worst. A red oak can go from healthy to dead in just a few weeks. White oaks get it too, but they die more slowly.

How Does Oak Wilt Spread?

Oak wilt spreads in two ways.

First, through the roots. Oak trees that grow close together often share roots underground. When one tree gets sick, the fungus travels through those shared roots to nearby trees. That is why you sometimes see a whole group of oaks dying at the same time.

Second, through beetles in spring. Small beetles carry the fungus from sick trees to healthy ones. They are most active from April through July. This is why you should never cut or prune oak trees between April 1 and July 15. Fresh cuts give the beetles a way in.

Signs Your Oak Tree Might Have Oak Wilt

Here is what to watch for:

• Leaves turning brown at the tips and edges, then spreading inward
• The whole top of the tree goes brown very fast — sometimes in just a few weeks
• Leaves falling off while they still have some green in them
• Dark streaks under the bark when you peel a small piece back
• More than one oak near each other all declining at the same time

What Should You Do?

Do not wait. Oak wilt moves fast.

Call a certified arborist right away. They can look at the tree, take a sample, and tell you for sure if it is oak wilt. Other problems can look similar, so it is important to get the right answer before doing anything.

If your tree does have oak wilt, here are some options:

• Trenching — digging a trench around the sick tree to cut off root connections and stop it from spreading underground
• Fungicide injection — a treatment injected into the trunk; works best early on or as prevention
• Tree removal — if the tree is too far gone, removing it the right way keeps the fungus from spreading

How to Protect Your Trees Before Problems Start

Only prune oaks in late summer or winter. In Wisconsin, that means August through March is safe. If a branch breaks during the risky season, put wound sealant on the cut right away.

Do not move oak firewood. The fungus can live in cut oak wood. Keep oak firewood away from healthy trees, and do not bring it in from other areas.

Get your trees checked regularly. A certified arborist can spot early warning signs before things get serious. This is really worth doing if you have several oaks on your property.

Oak Wilt Is a Real Problem in Madison

Dane County and the Madison area see oak wilt cases every year. Our neighborhoods have a lot of oaks, and the beetles that spread it are common here. This is not just a problem you read about in books — it happens in Madison yards all the time.

If you are not sure your oaks are healthy, let us take a look. Our ISA-certified arborists serve Madison and all of Dane County. We can check your trees and help you make a plan to keep them alive and healthy.

Call us or fill out our contact form for a free estimate. It is always better to catch a problem early than to deal with a dead tree later.