Southeast WI Forest Health

New oak wilt video released by DNR Forest Health Team

By Paul Cigan, DNR forest health specialist (Hayward),, 715-416-4920

Check out the new oak wilt video on the WI DNR Oak Wilt webpage.

New oak wilt video!

The DNR Forest Health Program just released a new oak wilt video  to educate the public about this deadly fungal disease that kills oak trees. In addition to the 3.5 minute video, a 30 second video trailer is also available:, each video may also be accessed from the Wisconsin DNR’s oak wilt webpage.

The videos, which are hosted on YouTube, may be shared through any networks of professional and public contacts who may benefit from viewing this resource. Please post the video on your organizational websites as an additional information source. Promotion of the videos is underway, including print ads in newspapers in several northern counties, DNR Facebook page posts, and an informational flyer distributed in northern counties. If you are interested in distributing flyers, please contact me or Jodie Ellis at for copies. Contact your regional forest health specialist for more details about prevention, detection, and management of oak wilt.



New! Statewide quarantine for emerald ash borer

by Jodie Ellis, Forest Health Team, communications specialist,, 608-266-2172

 An emerald ash borer adult.

An emerald ash borer adult.
Photo: Leah Bauer, USDA Forest Service Northern Research Station,

A statewide quarantine of the invasive insect emerald ash borer (EAB) will go into effect on March 30, 2018. Previously, individual counties were quarantined when EAB was confirmed within each’s borders. Since EAB has been found in 48 of 72 Wisconsin counties, officials have determined that statewide regulation of the devastating ash tree pest is warranted.

Movement of ash wood, untreated ash products and hardwood firewood of any type to areas outside of Wisconsin will continue to be regulated by USDA’s Animal and Plant Health Inspection Service, Plant Protection and Quarantine. (APHIS PPQ).

Within the state, Wisconsin businesses and members of the public will be able to freely move ash wood, ash products, and hardwood firewood to or from any Wisconsin county. Firewood restrictions will remain in effect on state and federal lands.

Items affected by the statewide EAB quarantine include ash wood with bark attached, larger ash wood chips, and hardwood firewood of any kind. County-by-county quarantines for gypsy moth, another invasive forest pest, remain in effect.

The move to a statewide quarantine does not mean that the state has given up on managing EAB; it is simply a shift in strategy as EAB continues its slow spread through the state. The Wisconsin DNR will continue releasing tiny, stingless wasps -natural enemies of EAB – at appropriate sites, which it has done since 2011. The DNR also continues participation in silvicultural trials in which different ash management strategies are being tested.

Most importantly, campers, tourists, and other members of the public are strongly encouraged to continue taking care when moving firewood within the state. “The actions taken by the Wisconsin public during the last few years have significantly slowed the spread of emerald ash borer and other invasive forest pests in the state,” said Wisconsin DNR EAB program manager Andrea Diss-Torrance. “We can continue to protect the numerous areas within our state that are not yet infested – including those in our own backyards – from tree-killing pests and diseases by following precautions.” Public members should continue to obtain firewood near campgrounds or cabins where they intend to burn it, or buy firewood that bears the DATCP-certified mark, meaning it has been properly seasoned or heat-treated to kill pests.

Emerald ash borer is native to China and probably entered the United States on packing material, showing up first in Michigan in 2002. It was first found in eastern Wisconsin in 2008.

For further information on EAB in Wisconsin, visit, using key words “emerald ash borer”.

New Wisconsin Wildcard available on beech bark disease

Written by: Linda Williams, forest health specialist, Woodruff., 715-356-5211 x232.

A new Wisconsin Wildcard is available on beech bark disease (BBD).  Wisconsin Wildcards are pocket-sized, collectible informational pieces available at Wisconsin state parks. The BBD Wildcard may be viewed at and ordered by emailing a request to (ask for publication no. FR-218x).

Beech bark disease will eventually become a problem wherever beech is found.  The native range of American beech (Fagus grandifolia) extends into the eastern third of Wisconsin. BBD is the result of a relationship between exotic scale insects and a Neonectria fungus. The disease was first identified in Wisconsin in 2009. Currently, the only known area of the state which has experienced mortality from BBD is Door County. 

Front and back of the new beech bark disease Wisconsin Wildcard.

Front and back of the new beech bark disease Wisconsin Wildcard.

The scale insects feed by inserting their mouthparts through the bark on the trunk and branches and sucking the sap from the tree. The fungus, which “hitchhikes” on the scale insects’ bodies, enters the tree through those wounds.  The tiny scale insects secrete a white waxy protective covering; when scale populations explode and there are millions of scales on a tree, the tree can appear white from a distance, making it resemble a birch tree. As the fungus enters the tree at numerous points and dead spots under the bark (called cankers) form, the tree becomes weakened, leading to a risk of “beech snap.”  Beech snap can occur unexpectedly when the tree still has a full canopy of leaves remaining.  Beech snap can create huge problems for park and campground managers who are trying to keep guests safe; there is no way to predict when a tree is going to fail from BBD.    

Hundreds of tiny scale insects (covered in white fluff) are present on this small area of beech bark.   

Hundreds of tiny scale insects (covered in white fluff) are present on this small area of beech bark. Photo: Linda Williams

Eventually, the insects and disease take their toll and the beech trees decline and die.  Any age of beech tree can be infested, so in stands with significant beech mortality, regenerating trees will become infested as well as mature ones.  The good news is that three to five percent of American beech trees are resistant to BBD.  Michigan has identified and propagated such trees for a number of years, and have established a seed orchard of resistant trees.  BBD is not yet as established in Wisconsin, but already we’ve been able to identify a couple of resistant trees in the area where BBD has killed many trees. 

For more info on beech bark disease, visit Wisconsin DNR’s webpage on BBD.









Defoliation by rose chafers and Japanese beetles is showing up.

Rose chafers and Japanese beetles are starting to cause problems in some areas this summer. So far reports and damage are generally light for Japanese beetles, but in some areas rose chafer defoliation is noticeable. 

Rose chafers are beetles that can defoliate many plant species. They have fairly long legs, and are a dusty mustard color.

Rose chafers are beetles that can defoliate many plant species. They have fairly long legs, and are a dusty mustard color.

Rose chafer defoliation was reported from Florence, Marinette, Oconto, Vilas, and Waupaca counties this year. Rose chafers are more common in areas with sandy soil where they will lay their eggs. The eggs hatch into white grubs which live in the soil and feed on grass and weed roots. My books inform me that birds can die if they eat adult rose chafers because of a poison in the beetles that affects the heart of small, warm-blooded animals. For information on rose chafer control, check out UW Extension publication A3122.

The last significant defoliation that I noted from rose chafer was in 2012, and before that it was 2005. These beetles feed on a wide variety of plants and prefer blossoms, but they will skeletonize leaves as well. Control is difficult because the adults are good fliers and can easily fly in from neighboring areas to re-infest your freshly sprayed plants. 

Japanese beetle populations will emerge in southern Wisconsin first, typically by the first part of July. Some areas of the state have building populations while others, like the Madison area, may have populations that exploded in the past and are more stable now. These insects are occasionally mistaken for EAB because they have some metallic green coloring near their heads.  More commonly people will refer to the multicolored Asian ladybeetles as Japanese beetles, but the ladybugs are ladybugs and Japanese beetles are scarab beetles.

Japanese beetle adults feed on the flowers and leaves of over 300 plant species, including trees, shrubs, and herbaceous plants. They can cause significant defoliation. The larval stage of Japanese beetle is a white grub that lives in the soil and feeds on plant roots.  University of Wisconsin Extension has a Japanese beetle webpage including information on the damage caused by the adults, the damage caused by the white grubs, and control measures that are useful on the adults and the larvae. 

Written by: Linda Williams, forest health specialist, Woodruff, (, 715-356-5211 x232.