South Central WI Forest Health

Protect oak trees from oak wilt by waiting until after July to prune

By Don Kissinger, DNR urban forester (Wausau), Don.Kissinger@wisconsin.gov, 715-359-5793 and Paul Cigan, DNR forest health specialist (Hayward), Paul.Cigan@wisconsin.gov, 715-416-4920

To protect oak trees and help prevent oak wilt, the Wisconsin Department of Natural Resources advises people to avoid pruning oaks on their property from April through July.

Spring and early summer pruning makes oak trees vulnerable to oak wilt, a fatal fungal disease that rapidly kills trees in the red oak group and weakens those in the white oak group. Any tree damage during this time creates an opening that exposes live tree tissue and provides an opportunity for the oak wilt fungus to infect the tree.

The red oak group includes northern pin oak, northern red oak, red oak and black oak; the white oak group includes bur oak, swamp white oak, white oak and English oak.

Pin oak (Quercus palustris)

Pin oak (Quercus palustris)
Photo: Gary Fewless, University of Wisconsin, Green Bay

“It takes only a few minutes for beetles that carry oak wilt spores to land on a fresh wound and infect your tree,” said Paul Cigan, DNR forest health specialist in Hayward.

Property owners with oak trees are encouraged to check with their municipality to find out if there are local oak wilt ordinances which may have different pruning restrictions.

The use of tree paint or a wound dressing is not normally recommended on pruning cuts or wounded surfaces on most trees. But for damaged oaks, the use of such products are suggested from April through July. An immediate light painting of wounds or cuts on oak trees during this time helps protect against the spread of oak wilt by beetles.

Don Kissinger, a DNR urban forester in Wausau, said there are also other important reasons to avoid pruning many kinds of deciduous trees in spring beyond concerns about oak wilt.

“Spring is the time when tree buds and leaves are growing, leaving the tree’s food reserves low,” Kissinger said. In general, the best time to prune trees is in winter.

Oak wilt and other diseases move easily on or in firewood logs year-round. To protect trees in general, don’t move firewood long distances, or only use firewood labeled as Wisconsin-certified.

As of January 31, 2018, oak wilt has been found in all Wisconsin counties except Douglas, Bayfield, Ashland, Iron, Forest, Taylor, Door, Kewaunee, Calumet, and Manitowoc counties. Several of these counties contain the highest abundance of healthy and productive oak forests in the state. Taking recommended precautions with living oak trees and keeping firewood local to prevent the spread of oak wilt will help keep them that way for years to come.

More information is available online at the WI DNR website, including a recently released video on oak wilt. Visit the DNR website, https://dnr.wi.gov/, and search for “oak wilt” or “firewood.” Additional information about proper pruning techniques is available from community foresters or by searching for “tree pruning.”

SPECIAL REQUEST from DNR’s Forest Health Team

Thank you to those kind subscribers who have already completed the Forest Health News Survey which was emailed in March. If you haven’t had a chance to take the survey, we ask that you do so now.

Our goal at Forest Health is to provide you with helpful information on pest, disease and invasive plant issues in the state in a timely manner. To help us improve our usefulness to you, please click here to take the survey.

The survey will take about 10 minutes to complete. Your individual responses will be kept confidential. All responses will be compiled and analyzed as a group; a summary of the survey results will be available to you this spring. If you own forested land in Wisconsin, you will need to refer to the zonal map which you will find at the beginning of the survey.

We would be grateful if you will complete the survey by April 15, 2018. If you have any questions or concerns about the survey or wish to provide additional comments about Forest Health News, please contact Jodie Ellis at Jodie.Ellis@wisconsin.gov or at 608-266-2172.

Thank you for taking the time to complete this survey. It is much appreciated.

Statewide quarantine for emerald ash borer

By Jodie Ellis, DNR Forest Health Team, communications specialist (Madison), Jodie.Ellis@wisconsin.gov, 608-266-2172

An adult emerald ash borer.

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

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) enacted a statewide quarantine for the invasive insect emerald ash borer  (EAB) 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, DATCP 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 https://dnr.wi.gov/ using key words “emerald ash borer.”

Be on the lookout for lesser celandine

By Michael Putnam, DNR invasive plants specialist (Madison), Michael.Putnam@wisconsin.gov, 608-266-7596

Lesser celandine flower

Lesser celandine flower. Photo: Wikimedia

Lesser celandine (Ranunculus ficaria) is an invasive forest plant that been found in urban forests in southeastern Wisconsin. The plant has a history of taking over forest floors in the eastern U. S. and crowding out native plants and tree seedlings. Consequently, lesser celandine is listed as a Prohibited Species under the state’s invasive species law NR 40, and cannot be transported, sold, introduced or possessed in Wisconsin.

DNR is undertaking control projects in Dane, Milwaukee, Racine and Kenosha counties – four of the six counties where lesser celandine is known to occur – and will be conducting surveys in the remaining two counties, Walworth and Waukesha, to inform future control efforts.

Lesser celandine with reproductive bulbils

Lesser celandine with reproductive bulbils Photo: DNR photo

Lesser celandine starts growing in early spring, with bright yellow flowers appearing in April. It dies back by the end of June. This low-growing plant has shiny, waxy leaves that are kidney or heart-shaped. Small spherical bulbils that form along the stems drop off to give rise to new plants, while underground tubers sustain the plant after it dies back. Because of its short growing season, DNR depends on reports from the public to identify new populations to plan accordingly. If you encounter this plant, please report it at Invasive.Species@wi.gov.

 

New oak wilt video released by DNR Forest Health Team

By Paul Cigan, DNR forest health specialist (Hayward), Paul.Cigan@Wisconsin.gov, 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 Jodie.Ellis@wisconsin.gov 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, Jodie.Ellis@wisconsin.gov, 608-266-2172

 An emerald ash borer adult.

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

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 https://dnr.wi.gov/, using key words “emerald ash borer”.

New Wisconsin Wildcard available on beech bark disease

Written by: Linda Williams, forest health specialist, Woodruff. Linda.Williams@wisconsin.gov, 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 https://p.widencdn.net/clz4yw/Beech-bark-disease-wildcard and ordered by emailing a request to Forestry.Webmail@wisconsin.gov (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.

 

 

 

 

 

 

 

 

Ash mortality in Central Wisconsin

Michael Hillstrom, forest health specialist, Fitchburg. michael.hillstrom@wisconsin.gov, 608-513-7690

Forest health has relayed the message over the last few years that stand level ash mortality from emerald ash borer (EAB) is occurring in southeast Wisconsin and along some parts of the Mississippi River. Those areas of mortality continue to progress each year, but stand level mortality is no longer limited to just these areas. 

All the ash in this stand near Roche-A-Cri State Park in Adams County are heavily flecked by woodpeckers feasting on EAB larvae. Extensive flecking indicates EAB has fully infested these trees and mortality is imminent. Photo by Mike Hillstrom.

February and March are good times to look for woodpecker damage to ash trees (known as “flecking”), and potentially find new EAB infestations or expansions of known infestations. Winter scouting has allowed us to detect ash mortality from EAB in unexpected places. I was in Adams County in mid-February looking for EAB biocontrol release sites.  I was shocked to find a stand where all the ash trees were heavily flecked and likely dead or close to it.  We had not previously confirmed EAB in that township or any of the townships directly surrounding it.

This incident further drove home the point for me that even isolated patches of ash are not safe from EAB. We are now past the point of thinking about taking action in ash stands in southern and central Wisconsin; we must now move forward with site assessments, with salvage/pre-salvage harvesting being a high priority for management.  In addition, non-ash regeneration growing should be started sooner rather than later. Of course, in urban settings, now is the time to prophylactically treat high-value ornamental ash trees.

The EAB silviculture guidelines will be revised in 2018; stay tuned.

 

Ice damage to yard and forest trees

Ice coating an urban tree from a late February 2017 storm in south central Wisconsin.

Ice coating an urban tree from a late February 2017 storm in south central Wisconsin.

Several ice storms have impacted yard and forest trees in southern Wisconsin in 2016/2017. The combination of trees coated in heavy ice and strong winds caused broken branches and bent or broken main stems. Working with storm damaged trees can be very dangerous, so landowners should carefully consider safety concerns and get help from  professional arborists or foresters when appropriate. Continue reading “Ice damage to yard and forest trees”