Oak Wilt in Madison, WI, and the Oak Work Permit

Oak wilt can kill a healthy red oak in a few weeks, and one careless pruning cut in May is all it takes to start it. That is why Madison regulates oak work for half the year, on private property as well as public. Here is how the disease works and how to stay on the right side of it.

By Tree Service Madison · Updated September 19, 2026 · Checked against the City and state sources listed below

What oak wilt is

A fungus that blocks the vessels an oak uses to move water. The tree wilts, as the name says, from the top down.

Oak wilt is a tree disease caused by a fungus that grows in the water-conducting tissue just under the bark. The oak responds by plugging its own vessels to wall the fungus off, and in doing so cuts off water to its leaves. The crown wilts, the leaves bronze and fall, and the tree dies.

How fast depends on the kind of oak. The red oak group, which in Madison means northern red, black, pin and Hill’s oak, has almost no defense. An infected red oak often goes from healthy to dead in four to six weeks. The white oak group, including white, bur and swamp white oak, resists far better. A white oak may lose a branch or two a year and linger for a long time, and some recover with treatment.

Oak wilt is established across southern Wisconsin, Dane County included. It matters in Madison more than most places because of what the city has to lose: the old bur and white oaks of the near west side, Nakoma and the Arboretum edge were standing before the streets were laid out, and they cannot be replaced in anyone’s lifetime.

How it spreads: over the ground, and under it

Two routes, and the rules only make sense once you know both.

Overland, by beetle

A red oak killed by oak wilt can form mats of fungus under its bark the following spring. The mats smell sweet and fermented, and they attract small sap beetles. The same beetles are attracted to the sap of a fresh wound on a healthy oak. They fly from one to the other, carrying spores, and they can find a fresh cut within minutes. This is how oak wilt jumps to a new street, and it is the route that people cause: every case started this way began with a wound made at the wrong time of year.

Underground, through the roots

Oaks of the same group growing near each other commonly fuse their roots into a shared network. Once one tree is infected, the fungus moves through those root grafts into its neighbors, and an expanding pocket of dead oaks appears over several years. This is how a single infection becomes a dead grove. It can be stopped only by cutting the root connections with a trenching machine, or by protecting the neighboring trees with fungicide before they are infected.

The two routes have different fixes. Timing rules, such as the oak work permit, deal with the beetles. Nothing but prompt action by a specialist deals with the roots.

The calendar: when oaks can be cut in Madison

Two authorities, one message. Leave oaks alone while the beetles are flying.

Risk follows the sap beetles. They are active from spring into early summer, tail off through late summer, and are gone once the weather turns cold.

The Wisconsin DNR advises against pruning, cutting or wounding oaks from April through July, when beetle activity and fresh spore mats coincide. It urges caution for the rest of the growing season, because the risk falls away gradually and does not reach zero until hard frost.

The City of Madison makes it law. Under Madison General Ordinance 23.40(7), any work on any oak inside the city between April 1 and October 15 requires a permit from Urban Forestry. It applies to private trees as well as public ones, and to pruning as well as removal. The permit is free.

How the oak work permit works

Who needs it: anyone pruning, cutting or removing an oak inside the City of Madison from April 1 to October 15. Homeowner or contractor, front yard or back.
Where to get it: the City’s Urban Forestry section, 608-266-4816. The City’s permit page, linked below, has the current application.
Emergencies: storm-damaged and hazardous oaks are permitted on an emergency basis, so urgent work is not held up. The wound is sealed at once in any case.
Who applies: ask Urban Forestry how they want it submitted. When we are hired for oak work inside the window, we take care of the application.
Outside Madison: the permit does not apply in Fitchburg, Verona, Middleton or the other suburbs. The DNR’s guidance does, and we follow it everywhere.

The simple way to stay clear of all of it is to schedule routine oak pruning for late fall and winter. The tree seals a dormant-season cut before the beetles return, the bare crown is easier to read, and frozen ground protects your lawn. See tree trimming and pruning.

What are you seeing on your oak?

Pick the closest match.

Leaves browning from the tips in summerOne branch at a time is dying, slowlyA storm just broke a limb, and it is summerA neighbor’s oak died last summerNothing is wrong. I just want it prunedI need an oak removed during the summer

Choose one above to see the answer.

Treat it as oak wilt until proven otherwise. On red, black and pin oaks the leaves turn dull green, then bronze from the tips and edges inward, and drop while partly green, often within a few weeks in June to August. Do not prune it. Have a sample tested, and call an ISA Certified Arborist.

Possibly oak wilt in a white or bur oak, possibly something else. White oaks decline a branch at a time over years, and can sometimes be saved by treatment. Two-lined chestnut borer, drought stress and root damage look similar. This needs a diagnosis from a certified arborist, not a guess.

Seal the wound now. The DNR advises covering a fresh oak wound within about fifteen minutes; any wound paint or latex paint will do. Then call us at (608) 571-1326. Inside Madison, the oak work permit for storm damage is handled on an emergency basis.

Your oaks may be at risk through the roots. Oaks of the same kind growing close together often share grafted roots, and the fungus moves through them. Ask a certified arborist about protecting your trees before symptoms appear. Treatment works far better as prevention.

Book it for the cold months. From October 16 to March 31 oak pruning needs no City permit and carries almost no oak wilt risk. The crown is bare and easy to read, and the ground is frozen. That is when we schedule all routine oak work.

Get the permit first. Removing an oak between April 1 and October 15 in Madison needs the free oak work permit from Urban Forestry (608-266-4816). If the tree can safely wait until mid October, waiting is better for every other oak on the block.

Red oak or white oak? Look at the leaf

Which group your tree belongs to tells you how fast the disease would move and whether treatment is worth discussing.

Red oak group: pointed lobes

The lobes of the leaf end in sharp points, each tipped with a tiny bristle. Northern red oak, black oak, pin oak and Hill’s (northern pin) oak belong here. Acorns take two years to mature. These are the trees oak wilt kills in a single summer, and the trees that form spore mats afterward, so a dead red oak is a danger to every oak around it.

White oak group: rounded lobes

The lobes are smooth and rounded, with no bristles. White oak, bur oak and swamp white oak belong here. Bur oak is the classic Madison savanna tree, with thick corky bark and fringed acorn caps. These trees decline slowly when infected, rarely form spore mats, and are the ones where fungicide treatment has a real chance.

What to do, situation by situation

Most of oak wilt control is knowing what not to do, and when to call someone.

A storm breaks your oak in summer

Do not wait for the permit to seal the wound. Cover every fresh break and cut with wound paint, or ordinary latex paint if that is what is in the garage, as soon as you can safely reach it. The DNR’s advice is within about fifteen minutes. Then call us. Cleaning up the break means more cuts, those get sealed too, and inside Madison the emergency permit covers the work. More on our emergency tree service page.

You suspect oak wilt

Do not prune the tree, and do not let anyone else. Get a diagnosis: an ISA Certified Arborist can take samples, and the UW–Madison Plant Disease Diagnostics Clinic tests them. Several other problems look similar from the ground, and the right response depends on which it is. Wisconsin has no state license for tree work, so ask to see the credential, and verify it at treesaregood.org.

Oak wilt is confirmed

Decisions now involve your neighbors’ trees as much as your own. The usual plan has three parts. Infected red oaks are removed before the following spring, so they cannot produce spore mats. Root connections to healthy oaks are cut by trenching where the site allows. And valuable oaks nearby are protected with fungicide injections, which must be given by a certified pesticide applicator and repeated every couple of years. Diagnosis and treatment are specialist work; the tree removal is ours.

The wood

Wood from an infected red oak stays infectious for about a year. Keep it on the property. Either have it chipped, which dries it fast enough to be safe, or stack it and cover the pile tightly with plastic, with the edges buried, until the bark falls away on its own. Never give it away as firewood in the meantime.

Planting and protecting oaks

None of this is a reason not to plant oaks. They are among the longest-lived and most valuable trees a Madison yard can have, and tree planting with a mix of species, including white-group oaks, is how the urban forest stays resilient. Protect the ones you have: no pruning in the growing season, no trenching or grade changes across their roots, and no lawn equipment against the trunk. Healthy trees resist everything better.

Sources, and a caveat

This guide is general information from a tree service, not legal advice, and ordinances change. Before you act on anything here, check the primary sources, or ask the agency directly.

Oak wilt questions from Madison homeowners

When is it safe to prune oak trees in Madison?

From October 16 through March 31. In those months the beetles that carry oak wilt are inactive and no City permit is needed. From April 1 to October 15 any oak work in the City of Madison requires a free permit, and the Wisconsin DNR advises against pruning oaks from April through July.

Does Madison’s oak permit apply to trees in my own yard?

Yes. Madison General Ordinance 23.40(7) covers every oak inside the City of Madison, on public or private property. Pruning, cutting or removing one between April 1 and October 15 requires a free permit from Urban Forestry, which you can reach at 608-266-4816.

How does oak wilt spread?

Two ways. Sap beetles carry spores from infected trees to fresh wounds on healthy oaks, mostly in spring and early summer. And the fungus moves underground through root grafts between neighboring oaks of the same group. The first starts new infections; the second spreads them.

Can an oak with oak wilt be saved?

Red, black and pin oaks almost never survive; they usually die within weeks of showing symptoms. White and bur oaks decline slowly and can sometimes be saved with fungicide injections by a certified applicator. Healthy oaks near an infected tree can often be protected the same way.

Should I paint pruning cuts on my trees?

Only on oaks, and only during the growing season. Wound paint does not help most trees and can slow sealing. On an oak wounded between April and October it is essential, because it keeps sap beetles off the fresh cut. Seal it immediately; minutes matter.

Can I keep firewood from an oak that died of oak wilt?

Yes, but do not move it. Wood from an infected oak can produce spore mats under the bark the following spring. Keep it on site, and cover the pile tightly with plastic, edges sealed to the ground, until the bark falls off on its own, usually a year. Then it is safe to burn.

More Madison tree guides

Tree Removal PermitsWhich trees need a City permit, which don’t, and which are not yours to cut.Terrace TreesWho owns, prunes, removes and replants the tree in front of your house.Emerald Ash BorerHow to spot it, when treatment still works, and why dead ash can’t wait.

All guides, or go straight to a service: tree removal, tree trimming and pruning, stump grinding, stump removal, emergency tree service.

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