South Central WI Forest Health

Eastern Tent Caterpillar Webs Common

Posted on by akabelowsky

Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665

Photo of web of eastern tent caterpillars.

Eastern tent caterpillars and their webs start out small but grow quickly. Photo: Linda Williams, Wisconsin DNR.

Have you seen trees along roadsides with white webs in them? Eastern tent caterpillars (ETC) are hatching and beginning to feed on host trees, including cherry, apple and crabapple.

Landowners and homeowners may notice the white silken tents forming in branch forks. Although they form unsightly nests, ETC is a native insect, so management is not typically necessary. Even completely defoliated trees will produce new leaves within a few weeks.

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Diseases Take Aim At Spongy Moth

Posted on by akabelowsky
Photo of tree showing caterpillars killed by virus and fungus

Caterpillars killed by nucleopolyhedrosis virus (NPV) hang in an inverted “V” orientation; caterpillars killed by the fungus Entomophaga maimaiga hang vertically. Photo: Wisconsin DNR.

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

With this spring’s dry weather in Wisconsin came predictions of the largest spongy moth population in years.

When spongy moth populations are high, we often see heavy mortality of the larger caterpillars due to two pathogens. Heavy caterpillar mortality will reduce the severity of the following year’s outbreak and often causes a population crash during the current year. If a heavy die-off of caterpillars is observed, please let your local DNR Forest Health Specialist know about it.

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Spongy Moth Focus Of Video, Webcast

Posted on by akabelowsky

Art Kabelowsky, DNR Forest Health outreach and communications specialist
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Add “YouTube Influencer” to the long list of career accomplishments of Andrea Diss-Torrance, Ph.D.

With the spongy moth caterpillar population on the rise in many areas of Wisconsin this season, the Wisconsin Department of Natural Resources stepped into action last month.

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Mystery Walnut Defoliator Identified

Posted on by patricialindquist

Article by: Mike Hillstrom, Forest Health Specialist

In 2020, forest health staff in Wisconsin, Minnesota and Iowa received calls about black walnut stands being defoliated and webbed. In 2021, the defoliation expanded to multiple additional black walnut stands in southwest Wisconsin, while northeast Iowa and Minnesota continued to see damage. Recently, molecular work completed by the Wisconsin Department of Agriculture, Trade and Consumer Protection has identified the larvae causing the damage as a native Tortricid moth, Gretchena amatana.

G. amatana caterpillars on tree.

G. amatana caterpillars on tree.

Fine webbing covers walnut tree trunk.

Fine webbing covers walnut tree trunk.

 

 

 

 

 

 

 

 

 

 

 

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Eau Claire And Richland Counties Now Added To The Gypsy Moth Quarantine

Posted on by patricialindquist

By Andrea Diss Torrance, Invasive Insects Program Coordinator, andrea.disstorrance@wisconsin.gov, 608-516-2223

Gypsy moth has moved slowly across Wisconsin in the last 30 years since gaining a foothold in the counties along Lake Michigan. This month, the Animal and Plant Health Inspection Service and the Department of Agriculture, Trade and Consumer Protection (DATCP) determined that the invasive pest has become established in Eau Claire and Richland counties and have extended the quarantined area to include them.  This is the first time since 2015 that new counties have been added to the quarantine. Fifty-two of Wisconsin’s 72 counties are now quarantined for gypsy moth.

Wisconsin Gypsy Moth Quarantined Counties

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Protect Oak Trees From Oak Wilt By Pruning After July, Not Before

Posted on by eleanorvoigt

By Don Kissinger, DNR Urban Forester, 715-348-5746 or Don.Kissinger@wisconsin.gov; Paul Cigan, DNR Forest Health Specialist, 715-416-4920 or Paul.Cigan@wisconsin.gov

The Wisconsin Department of Natural Resources (DNR) urban and forest health specialists recommend not pruning or cutting oaks from April through July to protect oak trees from the often fatal oak wilt disease.

The spring season often draws property owners outdoors to soak up rays of long-awaited sunlight, breathe in some fresh air and begin seasonal yard maintenance and cleanup projects. While spring is a time to dust off yard tools like rakes, shovels and weed clippers, when it comes to the health of oak trees, keeping those chainsaws and trimming tools a safe distance away will go a long way to ensure that your trees stay healthy for many more spring seasons to come.

Sap-feeding beetle on a diseased oak tree in Sawyer County.

Sap-feeding beetle on a diseased oak tree in Sawyer County.

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Treat Your Valuable Ash Trees Against Emerald Ash Borer

Posted on by eleanorvoigt

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

Property owners with healthy, valuable ash trees should consider treating them with insecticide this spring to protect against emerald ash borer (EAB). The 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. Now is an excellent time to consider insecticide protection because the treatments are typically done between mid-April and mid-May once leaves begin to return.

Treatments on already-infested ash trees are more likely to be successful if the trees have low or moderate levels of woodpecker damage.

An ash tree branch with bark missing after woodpeckers attacked it while looking for larvae to eat.

This ash tree branch in West Allis has been attacked by woodpeckers looking for larvae to eat.

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Look For Gypsy Moth Egg Masses And Prepare For Hatch; DATCP Slow-The-Spread Treatments Announced

Posted on by eleanorvoigt

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

Typically, gypsy moth egg masses hatch in April as temperatures warm. Now is a great time to do an egg mass inspection to look for unknown infestations and treat or remove any masses within reach. Each mass can result in 500 to 1,000 leaf-eating caterpillars.

Egg masses are tan-colored lumps and vary from about the size of a nickel to a quarter. They can be found on many outdoor surfaces such as tree trunks, the undersides of branches, buildings, rocks, fences, retaining walls, firewood piles and picnic tables.

Gypsy moth egg masses on the underside of a maple branch

Gypsy moth egg masses on the underside of a maple branch. 

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Oak Wilt Vectors Emergence User Interface Now Available

Posted on by eleanorvoigt

By Kyoko Scanlon, Forest Pathologist, Kyoko.Scanlon@wisconsin.gov or 608-235-7532 and Elly Voigt, Forest Health Communications Specialist and Lab Technician, Eleanor.Voigt@wisconsin.gov

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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Revised Factsheets, Guidelines Now Available

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By Elly Voigt, DNR Forest Health Lab Technician and Communications Specialist, Eleanor.Voigt@wisconsin.gov

The Wisconsin Department of Natural Resources (DNR) has just released several updated publications, including the annual update of the Heterobasidion root disease and oak wilt factsheets and guidelines. Updated versions can be found on the DNR’s forest health webpage by clicking the links below:

     – Heterobasidion root disease factsheet
     – Heterobasidion root disease guidelines
     – Oak wilt factsheet
     – Oak harvesting guidelines

Minor revisions were also made to the environmental cause of tree damage and conifer bark beetle factsheets. Visit the DNR webpage here for other forest health publications.

For more information on forest health, visit the DNR webpage, or talk to your regional Forest Health Specialist.