Care for your woods

Sign Up For Oak Wilt Vector Emergence Estimate Daily Email Notification

By Kyoko Scanlon, Forest Pathologist, Fitchburg, Kyoko.Scanlon@wisconsin.gov or 608-235-7532

Oak wilt is a serious disease that occurs when insects carrying oak wilt fungal spores land on a healthy oak tree’s fresh wound. To prevent oak wilt infections, it is important to avoid pruning, wounding and harvesting oaks when these insects are abundant, generally from April through July. Predicting exactly when these insects start to emerge in the spring can be difficult as their emergence is highly weather-dependent, and spring weather varies significantly from year to year.

In 2021, the Oak Wilt Vectors Emergence Thermal Model tool, a unique estimation tool, was developed as a collaborative project between the University of Wisconsin-Madison and the Wisconsin DNR to help with these predictions. This online tool offers localized recommendations about the emergence status of the two most important insects that transmit oak wilt in Wisconsin. The interface uses a degree-day model (Jagemann et al., 2018) constructed from insect trapping data and actual weather data, which helps refine the beginning of the periods when you should avoid pruning, wounding or harvesting oaks.

A screen shot of the oak wilt vector emergence homepage where the location and date data is entered to model growing degree days.

UW Extension’s Oak Wilt Vectors Emergence Thermal Model can help predict when oak wilt vectors may be coming. Photo Credit: UW Extension

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Make Plans To Control Spongy Moth Before The Eggs Hatch

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

Spongy moth (formerly known as gypsy moth) egg masses typically begin to hatch in April as temperatures warm. Each mass that hatches may produce up to 1,000 leaf-eating caterpillars.

Now is a great time to inspect your trees for egg masses and treat or remove any masses within reach. Wisconsin weather has been favorable for this pest over the last three years and populations have grown.

Photo of three spongy moth egg masses on the underside of a pine branch in Walworth County.

Three spongy moth egg masses on the underside of a pine branch in Walworth County. Photo: Bill McNee, Wisconsin DNR.

Continue reading “Make Plans To Control Spongy Moth Before The Eggs Hatch”

Spongy Moth Management Webinar: March 8 at 6 p.m.

By Michael Hillstrom, Forest Health Specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov

Spongy moth populations increased dramatically in 2022 and the outbreak is expected to continue in 2023.

Landowners interested in learning more about spongy moth management options are encouraged to attend an upcoming webinar hosted by UW Extension at 6 p.m. on March 8, 2023.

This is a free event, but registration is required. DNR Forest Health Specialist Mike Hillstrom and UW-Madison Insect Diagnostic Lab entomologist PJ Liesch will discuss a variety of effective management tactics for reducing spongy moth damage in varied settings from high value urban trees to forests.

A flyer for an upcoming webinar about spongy moth management that will take place virtually at 6pm on March 8, 2023.

UW Extension’s spongy moth management webinar can help you prepare to care for your land this spring.

Make Your 2023 Spongy Moth Treatment Plans Early

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

As long as weather conditions are favorable for the spongy moth* (formerly known as gypsy moth) population, the current outbreak is predicted to continue and spread to other parts of Wisconsin in 2023. Property owners are encouraged to examine susceptible host trees (including oak, birch, crabapple, aspen and willow) and plan ahead.

Spongy moth egg masses on a tree next to a penny for size comparison.

Spongy moth egg masses are tan-colored lumps that are larger than a penny, about the size of a nickel or quarter. Photo: Wisconsin DNR

Continue reading “Make Your 2023 Spongy Moth Treatment Plans Early”

Harvest Timing Affected By Spongy Moth

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

Numerous spongy moth egg masses on a bur oak in southern Waukesha County, November 2022.

Numerous spongy moth egg masses on a bur oak in southern Waukesha County, November 2022. Photo: Bill McNee, Wisconsin DNR.

Forest managers planning silvicultural treatments in spongy moth susceptible stands (containing a large proportion of host species including oak, birch, aspen and basswood) are encouraged to annually conduct egg mass surveys in the few years prior to the scheduled treatment to predict if heavy defoliation is likely. The results may indicate that management activities should be altered or delayed until an outbreak has ended. At present, stands that were heavily defoliated in 2022 or are predicted to be heavily defoliated in 2023 are most likely to need a management delay or alteration.

It is recommended that a time interval be left between a stress agent (such as heavy defoliation or significant drought) and stand thinning so that the trees can recover from pre-existing stress before being subjected to additional stress. One growing season is a common interval for healthy stands that are not being subjected to drought or other stresses. A longer interval is suggested if the tree stress has been more severe or if the stand was not healthy and vigorously growing at the time of defoliation. The same interval is probably appropriate regardless of which stress agent is the pre-existing one. A protective aerial spray may prevent tree stress from defoliation but is usually not economically viable due to the high cost of an aerial treatment.

Continue reading “Harvest Timing Affected By Spongy Moth”

Don’t Dump Your Garden Waste

By Jaqi Christopher, DNR Forest Invasive Plant Specialist, Rhinelander, Jacquelyn.christopher@wisconsin.gov

When cleaning up your garden this fall, be sure to dispose of yard waste properly. Not only is dumping on public lands illegal, but it is harmful to the environment.

A large pile of pine needles, leaves and branches dumped along the forest edge.

This garden waste was dumped along an ATV trail in a state forest and can be a pathway for invasive plants and diseases that affect our public lands. Photo: Wisconsin DNR

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Twolined Chestnut Borer Attacks On The Rise

By Paul Cigan, DNR Forest Health Specialist, Hayward, Paul.Cigan@wisconsin.gov or 715-416-4920

Twolined chestnut borer (TLCB) attacks on oak trees have increased in numerous Wisconsin counties, with decline and associated mortality in the last two growing seasons, most noticeably since August.

Symptoms of infestation by this native beetle are initially seen in mid-July on the outer portions of branches in the upper crown. Leaves begin to fade from green to yellow to red. Within a matter of weeks, they turn brown and remain on the branches for weeks to months. Their foliage may also appear sparse or completely bare (Fig. 1).

Trees with twolined chestnut borer symptoms

Figure 1. Northern red oaks with symptoms of twolined chestnut borer, ranging from crown thinning and leaf chlorosis like the tree on the left (early stage) to dead top branches like the tree on the right (intermediate stage). Photo: Wisconsin DNR

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Moving Firewood Can Spread Invasive Species

An image of an insect walking away from burning firewood in a forest with the caption, “Buy it where you burn it.”

Don’t Move Firewood, The Nature Conservancy

October is Firewood Month! Help prevent the spread of invasive insects and diseases by buying firewood where you burn it.

Firewood Scout can help you find local firewood for sale.

See the DNR website for more information on invasive species and forest health. Continue reading “Moving Firewood Can Spread Invasive Species”

Look For Spongy Moth Egg Masses – Larger Outbreak Possible in 2023

By: Bill McNee, DNR Forest Health Specialist, Oshkosh

bill.mcnee@wisconsin.gov or 920-360-0942

Three tan-colored spongy moth egg masses on a single tree branch in Walworth County.

Three spongy moth egg masses on a branch in Walworth County. Photo Credit: Bill McNee, Wisconsin DNR

Now that spongy moth* (formerly known as gypsy moth) egg laying is complete for 2022, it’s a good time to look for and dispose of egg masses produced by adult moths over the past two months.

Spongy moth egg masses are tan-colored lumps about the size of a nickel or quarter, and are found on trees, buildings and other outdoor objects. They may also be found in protected places such as firewood piles and birdhouses. Newly produced egg masses will feel firm and appear darker in color than older egg masses, which appear faded, feel spongy and do not contain viable eggs. The current-year egg masses will not hatch until next spring.

In 2022, Wisconsin’s spongy moth population grew for a third consecutive summer due to favorable weather conditions and limited caterpillar mortality from diseases. The outbreak was most dramatic in opposite ends of the state. In southern and southeast Wisconsin, several thousand oak-dominated acres were heavily defoliated and very large numbers of property owner reports were received by DNR staff. In Bayfield County, about 80,000 acres of rural defoliation was reported from aspen-dominated forests. Smaller patches of defoliation were also reported from several other counties. Continue reading “Look For Spongy Moth Egg Masses – Larger Outbreak Possible in 2023”

Trees Will Need More Water this Summer

We are likely to see a hotter than average summer, which means you, your pets, your plants, and yes, your trees, will need more water!

Stress from drought can affect all plants, from a newly planted sapling to a well-established, mature tree. Trees that are already weakened from other types of stress, such as tree leaf predation by spongy moths, are of particular concern.

See our watering tips below for how you can help!

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