Taking action

Oak Wilt High Risk Period Quickly Approaches

Posted on by akabelowsky
A closeup of a fungal pressure pad under the bark of an oak tree infected with oak wilt.

A fungal pressure pad formed on the outside of the sapwood underneath the bark of an infected tree. The pad will create cracks in the bark, where beetles can enter and visit the pad and become covered in spores. They will then leave and move on to infect new trees through open wounds. / Photo Credit: Wisconsin DNR

By Alex Hornung, DNR Forest Health Specialist, Plover
Alexandra.Hornung@wisconsin.gov or 715-340-3810

It is again that time of year to pause operating in oak stands or pruning oak trees during the high-risk period for oak wilt, which begins in April. The high-risk period begins April 1 in the South, April 15 in the North, and ends in both zones on July 15.

The high-risk period is determined by when the beetles that carry the fungus that causes oak wilt have emerged for the year and when they are carrying the highest number of fungal spores. When wounds are created by logging operations or other activities that expose sapwood, the beetles carry the fungus to the wounded tree, and the disease process begins.

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Protect Valuable Ash Trees Against Emerald Ash Borer

Posted on by akabelowsky
An ash tree in Oshkosh shows damage from woodpeckers feeding on emerald ash borer larvae beneath the bark.

An ash tree next to a walking trail in Oshkosh has been damaged by woodpeckers feeding on emerald ash borer larvae beneath the bark. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov or 920-360-0942

Property owners with healthy, valuable ash trees are encouraged to treat them with insecticide this spring to protect against emerald ash borer (EAB).

The invasive pest is currently the most damaging threat to trees in Wisconsin, killing more than 99% of the ash trees it infests.

Woodpecker damage during the winter is often the first sign that an ash tree is infested. The birds remove pieces of bark while feeding on EAB larvae inside the tree. Insecticide treatment of infested ash trees is more likely to be successful if the trees have low or moderate levels of woodpecker damage.

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Wisconsin’s Urban Forestry Council 2025 Biennial Report Published

Posted on by janness

By Jenn Janness, Urban Forestry Council Liaison
Jennipher.Janness@wisconsin.gov or 920-809-9330

2025 report coverThe purpose of the Wisconsin Urban Forestry Council is to advise the state forester and the Wisconsin DNR on the best ways to preserve, protect, expand and improve Wisconsin’s urban and community forest resources. Members are appointed by the DNR Secretary and represent a wide array of stakeholders, including municipal and utility foresters, medical and higher education professionals, nursery and green industry staff, environmental groups, public works and parks staff, organizations such as the Wisconsin Arborist Association (WAA), the Urban Wood Network Wisconsin, the League of Wisconsin Municipalities and government agencies such as WisDOT and DATCP. Continue reading “Wisconsin’s Urban Forestry Council 2025 Biennial Report Published” →

Now Is Time To Seek Out Spongy Moth Egg Masses

Posted on by akabelowsky
Large spongy moth egg masses on a tree main stem.

Large egg masses are seen on a tree at the Kettle Moraine State Forest-Southern Unit in 2021. / Photo Credit: Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov

It certainly has been chilly in recent weeks, but spring is coming. When the weather warms up, the annual return of spongy moth caterpillars will begin.

The overall spongy moth population is currently low in Wisconsin. However, egg mass numbers may remain high enough to cause nuisance problems and heavy tree defoliation on individual trees or in small areas.

There’s a way for property owners to help keep the population down: Get out now to locate and properly dispose of spongy moth egg masses, which were produced by adult moths last summer. Each spongy moth egg mass contains hundreds of eggs that will hatch into hungry, leaf-eating caterpillars in the spring.

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Make Plans For National Invasives Week

Posted on by akabelowsky
Workers spray water from a hose to clean the wheels of a tractor in a woodlot.

Workers follow the practice of pressure-washing the tires and frames of a tractor to rid the vehicle of possible invasive plants after a workday in the forest. / Photo Credit: Wisconsin DNR

By Art Kabelowsky, DNR Outreach and Communications
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

The North American Invasives Species Management Association (NAISMA) has organized a series of activities to take place as part of its National Invasive Species Awareness Week (NISAW), set for Feb. 23 through 27.

The Wisconsin Department of Natural Resources will participate by presenting a news release and daily social media posts in the days leading up to the start of NISAW’s 2026 activities.

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Correction On Plans For Discarding Holiday Decorations

Posted on by akabelowsky
A pile of discarded Christmas trees in a drop-off lot.

A stack of discarded Christmas trees awaits processing at a drop-off facility. / Photo Credit: Wisconsin DNR

By Wisconsin DNR

An article in the January edition of the Wisconsin Department of Natural Resources’ Forest Health News contained some incorrect information on the disposal of wreaths, trees, boughs and other holiday decorations.

The article focused on disposing holiday plant matter in ways that avoided the spread of invasive insects, seeds and spores that can spread to harm trees, plants and habitats.

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Time To Consider A WMA-PFGP Grant Application

Posted on by akabelowsky
Volunteers working to remove invasive plants from a riverside forested area.

Volunteers at a garlic mustard-pulling event on the Montreal River in Iron County, part of a control project planned by a previous WMA-PFGP recipient. / Photo Credit: Ramona Shackleford, Northwoods Cooperative Weed Management Area

By Art Kabelowsky, DNR Outreach and Communications
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

With an April 1 deadline on the horizon, it’s time for eligible Weed Management Groups (WMGs) to consider applying for a Weed Management Area-Private Forest Grant Program (WMA-PFGP) grant to address invasive forest plants in 2026.

The WMA-PFGP helps eligible groups both by dealing directly with the invasives and by providing education, information and outreach to others. The grants are meant as reimbursements that cover up to 75% of eligible costs, with a 25% match required.

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When Is The Best Time To Prune Trees?

Posted on by janness

By Elton Rogers, DNR Urban Forestry Coordinator
Elton.Rogers@wisconsin.gov or 414-294-8675

To best answer the titular question, I like to start by flipping the question on its head: When is the worst time to prune trees?

To answer this reworded question, we first need to acknowledge that “pruning is wounding.” Anytime you cut off a living portion of a tree, you are doing two main things:

  • Removing photosynthetic material.
  • Creating a potential entry point for decay.

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