Central WI Forest Health

New! Statewide quarantine for emerald ash borer

Posted on by jodieellis

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

Posted on by jodieellis

Written by: Linda Williams, forest health specialist, Woodruff. Linda.Williams@wisconsin.gov, 920-360-0665.

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 here. If you’d like to order them, send 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

Posted on by jodieellis

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.

 

Oak skeletonizer showed up late this season

Posted on by colleenrobinson
Oak skeletonizer is a tiny caterpillar that feeds on oak by removing just the lower layers of the leaf, leaving the paper-thin upper epidermal layer.

Oak skeletonizer is a tiny caterpillar that feeds on oak by removing just the lower layers of the leaf, leaving the paper-thin upper epidermal layer.

This is the same leaf as above, just being held up to the sky so you can see how there is one very thin layer of leaf left where oak skeletonizer was feeding.

These two pictures are of the same leaf.  In this photo, the leaf is being held up to light to show how there is one very thin layer of leaf left where oak skeletonizer was feeding.

Oak skeletonizer (Bucculatrix ainsliella) is a native insect that defoliates oak in Wisconsin. Damage was observed in most counties in northeast and central Wisconsin. There are two generations per year. Damage from the first generation this year barely showed up at all, but defoliation by the second generation became quite noticeable in late August and September. Continue reading “Oak skeletonizer showed up late this season” →

Jumping galls cause defoliation on white oaks

Posted on by colleenrobinson
Brown areas on these white oak leaves were caused by a heavy infestation of jumping oak gall.

Brown areas on these white oak leaves were caused by a heavy infestation of jumping oak gall.

Jumping oak galls caused by tiny wasps form on the underside of white oak leaves.

Jumping oak galls caused by tiny wasps form on the underside of white oak leaves.

If you were in Waupaca County this summer, you probably noticed that large white oaks were looking pretty brown. They were being defoliated by a tiny gall wasp called jumping oak gall (Neuroterus saltatorius). The small galls, which develop around tiny larvae on the undersides of oak leaves, fall off the leaves in late summer. Continue reading “Jumping galls cause defoliation on white oaks” →

Defoliation by rose chafers and Japanese beetles is showing up.

Posted on by colleenrobinson

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, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Spruce budworm defoliation is present

Posted on by colleenrobinson
Spruce budworm defoliation is not as noticeable this year, although it is still present as you can see here with many needles missing.

Spruce budworm defoliation is not as noticeable this year, although it is still present as you can see here with many needles missing.

Spruce budworm damage is present this year but in many areas it is less noticeable than in past years. I believe this is due to a couple of things:

  1. The many storms we had this spring with heavy rainfall and strong winds may have washed some of the caterpillars out of the trees. They definitely washed budworm damaged needles off the tree. Damaged needles typically remain on the tree and turn a rusty brown, so not having these needles on the tree makes it less obvious where defoliation is present this year.
  2. Due to the constant rainfall this year, the growth on balsam fir and spruce seems to be quite good in general, which leads to additional green needles on the tree this year. This makes the trees look more green and less defoliated, but spruce budworm is still there.

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

Oak wilt signs are showing up

Posted on by colleenrobinson
Oak leaves from an oak wilt infected tree. The outer portions of the leaf will be brown or have a water-soaked appearance. Part of the leaf remains green even though the leaf has dropped off the tree.

Oak leaves from an oak wilt infected tree. The outer portions of the leaf will be brown or have a water-soaked appearance. Part of the leaf remains green even though the leaf has dropped off the tree.

Trees that were infected with the oak wilt fungus this spring, (whether from overland spread by beetles or underground spread by connected root systems) are beginning to drop their leaves. Leaves can drop anytime between July and September. This wilting and dropping of the leaves happens fairly quickly, and trees can go from looking nice and healthy to having lost most of their leaves within just a few weeks. This year I saw my first wilting oaks on June 28, although in areas further south the leaf drop may have begun earlier. Oak wilt is a non-curable, fungal disease specific to oaks. Once the fungus infects a tree it will begin to spread outward from the roots of the infected tree through grafted roots and into the roots of neighboring oaks, eventually killing the neighboring oaks. In this way pockets of dead oak will be created as each year more oaks die. For more information on oak wilt biology, prevention, and control check out the WI DNR’s oak wilt page. 

Firewood from trees that have died from oak wilt will remain infectious for 1 full year (12 months) after the tree has died. There are many areas of northern Wisconsin where oak wilt is not common. Please do not move firewood long distances because you could move oak wilt into a new area.

Many northern counties don’t have oak wilt or have only a few known infections. This map shows townships in the north where oak wilt has been identified. In the red counties oak wilt is considered to be scattered throughout the county, although it will not be found in every stand.

Many northern counties don’t have oak wilt or have only a few known infections. This map shows townships in the north where oak wilt has been identified. In the red counties oak wilt is considered to be scattered throughout the county, although it will not be found in every stand.

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

Tamarack defoliation by larch casebearer

Posted on by colleenrobinson
A patch of brown tamarack trees defoliated by larch casebearer caterpillars photographed during aerial survey in early June.

Larch casebearer defoliation visible from an aerial survey on June 7, 2017. Photo by Josh Haberstroh.

Tamarack defoliation by larch casebearer is evident in northcentral and northeastern Wisconsin again in 2017. The most severe defoliation occurred in Lincoln and Langlade counties, while more moderate defoliation was noted in Waupaca, Shawano and Oneida counties. I saw extensive damage in northern Wisconsin by this insect in 2014 but damage was much more localized and less severe in 2015 and no damage was documented in 2016.

Larch casebearer, Coleophora laricella, overwinters as young caterpillars and is able to start feeding as soon as the weather warms up in the spring. The caterpillars mine out the needles of tamarack causing them to turn brown by late spring. Tamarack trees will typically produce new needles after moderate or severe damage. Caterpillars pupate on the tree in early summer and moths mate and lay eggs in summer. A second round of feeding, which causes additional stress to the trees, occurs by young larvae in summer before they overwinter. Repeated defoliation can weaken the tree, making it more susceptible to mortality from eastern larch beetle.

Written by: Mike Hillstrom, forest health specialist, Fitchburg, (Michael.Hillstrom@wisconsin.gov), 608-513-7690

Yellowheaded spruce sawfly

Posted on by colleenrobinson
There are 2 young yellowheaded spruce sawfly in this photo. As they get older they develop an orangish head capsule.

There are 2 young yellowheaded spruce sawfly in this photo. As they get older they develop an orangish head capsule.

Has anyone started to see defoliation from Yellowheaded Spruce Sawfly? This small sawfly seems to defoliate spruce without anyone noticing until it’s all done. We saw significant defoliation in 2015 (Door, Marinette, and Vilas counties) and 2016 (Outagamie, Shawano, and Waupaca counties) and if the population is going to remain high this year you should start seeing the defoliation soon. There is one generation per year and they typically feed on new expanding foliage from late May to early July. They will feed on all spruce (white, blue, Norway). The larvae blend in well with the needles so you’ll have to look closely as they can be difficult to spot.

If you have had defoliation in previous years from Yellowheaded Spruce sawfly you should monitor your spruce to determine if spraying will be necessary this year. Repeated severe defoliation can cause tree mortality.  More info can be found in this Forest Service publication.

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