Care for your woods

Oak Wilt Vectors Emergence User Interface Now Available

By Kyoko Scanlon, Forest Pathologist, or 608-235-7532 and Elly Voigt, Forest Health Communications Specialist and Lab Technician,

Oak wilt is a serious disease of oaks that spreads to new areas when insects carrying oak wilt fungal spores land on a fresh wound of a healthy oak tree. To prevent oak wilt infections, it is important to avoid pruning, wounding and harvesting of oaks when these insects are abundant.

Predicting when these insects emerge in spring can be difficult as their emergence is highly weather-dependent and spring weather varies significantly year to year. The good news is that a new online interface is now available to provide users with localized information about the emergence status of the two most important insects that transmit oak wilt in Wisconsin. Because the interface uses a degree-day model constructed from insect trapping data and actual weather data, it is useful to refine the beginning of the periods when pruning, wounding and harvesting of oaks should be avoided.

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Featured Species: Washington Hawthorn

T. Davis Sydnor, The Ohio State University,

Scientific Name: Crataegus phaenopyrum

Native to: East Central U.S. (southern Illinois, Kentucky, Tennessee and southeastern Missouri)

Mature Height*: 20 to 30 feet

Spread*: 20 to 30 feet

Form: upright oval to rounded vase shape; has 1 to 3-inch thorns (some cultivars have fewer thorns)

Growth Rate*: slow-moderate

Foliage: alternate, simple, triangular-shaped, three to five-lobed, doubly serrate margin and dark green in summer

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New emerald ash borer county detections: an update from DATCP and DNR

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), in partnership with the Wisconsin DNR, has detected emerald ash borer in four new counties (Dunn, Oconto, Pepin and Shawano). Please read this DATCP article for more information.

Adult emerald ash borer beetle.

Adult emerald ash borer beetle.

If you are a landowner and have questions about ash trees in your woodlot, contact your local DNR forester using the Forestry Assistance Locator.  

Gypsy moth populations rebound in 2020 – look for egg masses this fall

By Bill McNee, forest health specialist, Oshkosh,, 920-360-0942

The summer of 2020 saw a major rebound of the gypsy moth population after several years of weather conditions that were unfavorable for the non-native, defoliating pest. A mild winter and average summer temperatures/precipitation during the caterpillar stage were all favorable for a population increase.

Gypsy moth egg masses are tan-colored lumps about the size of a nickel or quarter.

Female moth laying eggs on tree trunk.

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Interactive HRD stump treatment guidelines available online

The HRD stump treatment guidelines are now available in an interactive format to make it easier to obtain stand-specific recommendations. You can find the link called “Interactive guidelines” on the right side bar under “Additional Resources” at the DNR HRD webpage. The user will be asked a series of questions and then a stand-specific recommendation will be provided at the end. The interactive guidelines incorporate Exceptions and Modifications described in the guidelines. Check it out!        

Report surviving elm in the forest

You can help keep native elm trees in the forests of Wisconsin! The US Forest Service continues to work on a project to identify Dutch elm disease (DED)-tolerant American elms native to Wisconsin forests. The goal of the project is to identify and propagate survivor American elms, especially from the colder hardiness zones 3-4, and develop a series of clone banks. Selections would eventually be screened for tolerance to DED. Ultimately, the goal is to make DED-tolerant American elm available for reforestation in northern areas, particularly as a component on sites currently forested by black ash.

If you live in hardiness zones 3 and 4, please look for evidence of surviving elms and report them to the US Forest Service.

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Arbor Day 2020: Celebrating trees in a time of social distancing

Many Wisconsin communities found creative and resourceful ways to celebrate Arbor Day this year. These celebrations included drive-through tree giveaways, videos, art contests, games and puzzles, self-guided tree walks, small in-person celebrations and tree planting following social distancing guidelines, and more! Here is a sampling of the Arbor Day events that took place in Wisconsin this spring:

Adams: The city of Adams held a celebration on April 16th. Mayor Roberta Pantaleo read the Arbor Day Proclamation, and City Forester Joel Fell and another public works employee planted two trees in Burt Morris Park and four trees along boulevards.

Cedarburg: Please follow this link to read how Cedarburg Green celebrated its Year of the Tree despite Covid-19.

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Cedarburg Green celebrates Year of the Tree despite Covid-19

By Jeanne Mueller, Cedarburg Green

“2020 is the year to focus on trees” read the headline in Cedarburg’s local newspaper. In January, a proclamation signed by Cedarburg’s mayor kicked off Cedarburg Green’s yearlong, multi-faceted promotion of trees. Cedarburg Green’s first success, a community talk on “Selecting the Right Trees for your Yard”, exceeded attendance expectations by over 225%. Interest in trees at this standing-room-only, inaugural event, held on February 24, seemed to be setting the stage for great things to come. Another hopeful sign was the mounting orders for trees being received as part of the organization’s annual bare-root tree sale.

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Updated emerald ash borer silviculture guidelines now available

By Bill McNee, forest health specialist, Oshkosh,, 920-360-0942

The Division of Forestry has completed a revision of the emerald ash borer silviculture guidelines to help foresters prepare for and respond to the arrival of emerald ash borer (EAB) in a forest stand.

Cover page of new guidelines. Continue reading “Updated emerald ash borer silviculture guidelines now available”

New insect and disease factsheets available

By Mike Hillstrom, forest health specialist, Fitchburg,, 608-513-7690

The forest health team has produced four new factsheets since the start of 2020. These resources are designed to be informative, 2-page documents for a wide audience that includes landowners, foresters and natural resource professionals, educators, and more. The new factsheets of 2020 are linked below, and more will be announced as they are finalized:

Please check them out and our other recently updated factsheets about Heterobasidion root disease, oak wilt, conifer bark beetles, and hickory decline and mortality. You can find all of these and more forest health publications in the publications catalogue and on the DNR forest health webpage.