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Be on the lookout for lesser celandine

Posted on by jodieellis

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

Posted on by jodieellis

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.

 

 

Woodpecker damage is easy to spot during the winter

Posted on by jodieellis

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

Two elm trees with varying levels of bark stripping caused by woodpeckers feeding on larvae beneath the bark.

Two elm trees with varying levels of bark stripping caused by woodpeckers feeding on larvae beneath the bark. Photos: Linda Williams

Have you noticed any trees this winter with the bark partially or mostly removed? These trees can stand out dramatically during the winter. Woodpeckers remove outer layers of bark so that they can more easily punch their beaks through the remaining bark to get at the tasty, plump larvae underneath. The three most common trees that you’ll spot this damage on in Wisconsin are elm, tamarack, and ash. So, what’s going on?

On elm, there are three bark beetles of interest. One is a native beetle, and two are exotic species – the smaller European elm bark beetle and the banded elm bark beetle. Adult bark beetles chew their way under bark and lay eggs during the spring or summer. The eggs hatch, and larvae begin feeding in the tree layers under the bark. Going into winter, larvae are plump and delicious (if you’re a woodpecker), and it’s these juicy morsels for which the woodpeckers will strip the outer bark from the tree, sometimes starting at the ground and working all the way to the top. Elm trees will often appear a rich red or burgundy color when outer bark is removed. The U.S. Forest Service offers a document with additional information on elm bark beetles, as well as photos of each of them.

Close-up of tamarack bark, showing the larvae of Eastern bark beetle at the tip of my (broken) knife. Woodpeckers remove the outer bark to make it easier to access these tasty morsels.

Close-up of tamarack bark, showing the larvae of Eastern bark beetle at the tip of my (broken) knife. Woodpeckers remove the outer bark to make it easier to access these tasty morsels.

Tamarack trees (often referred to as larches) are attacked by a bark beetle as well. Eastern larch beetles attack stressed tamarack trees, although sometimes the stress is so minor that it’s not easily identifiable. The wet weather we had throughout the 2017 growing season definitely stressed some of tamaracks in Wisconsin; having roots in fully saturated soils for too long a period when the tree is actively growing can cause root mortality. Tamarack that have had the outer bark stripped off will appear dark red in color. More information on eastern larch beetle from the U.S. Forest Service can be found here.

Ash bark with pale areas where woodpeckers have removed outer layers of bark, as well as some small rough holes where the woodpeckers punched through bark and plucked out a nice plump EAB larvae.

Ash bark with pale areas where woodpeckers have removed outer layers of bark, as well as some small rough holes where the woodpeckers punched through bark and plucked out a nice plump EAB larvae.

Ash trees with the outer bark removed may be infested with either emerald ash borer or a native ash bark beetle. When woodpeckers remove outer bark of an ash tree, it makes the tree look very pale. Emerald ash borer populations build up to very high numbers as they move into new areas, which provides a great source of food for woodpeckers. A study published in 2012 showed that woodpecker numbers can increase due to the presence of EAB.

 

What about other woodpecker damage that you see on trees?

Pileated woodpeckers are large birds that can do a significant amount of damage to trees. The good news is that they tend to target trees that are dead or have a lot of decay in them. That’s not

to say that they won’t occasionally peck into a healthy tree, but the insects they prefer to feed on are more common in dead or severely stressed trees, or trees with a lot of decay in them. Pileated woodpeckers have tongues containing backward facing barbs that they can stick into an insect gallery to drag out the occupants for a meal. They can leave a pile of good-sized woodchips at the base of trees that they’re feeding in. The photo shows an example of the damage that they can do.

Sapsuckers are birds that drill orderly rows of holes through the bark of trees. The holes go through the bark to the cambial layer, causing the tree to “bleed” sap. Sapsuckers return to feed when the sap is flowing. Sapsuckers’ tongues have little hairs on them to help gather sap. Sapsuckers are migratory and may just pass through an area in the spring, but they will sometimes return to the same tree over multiple years, creating new rows of holes each year. Trees will attempt to grow over this damage, and are usually successful, although the damage to the bark may remain visible for many years. Loggers may note this damage when cutting logs; it is referred to as “bird peck”, and is considered a defect. Federal regulations prohibit people from killing sapsuckers, so control for yard trees is usually some manner of deterrent such as wrapping the main stem with hardware cloth or burlap, or using scare tactics in the tree.

Orderly rows of holes created by yellow-bellied sapsuckers. These birds will revisit these holes that they drill and lick the sap that flows from them.

Orderly rows of holes created by yellow-bellied sapsuckers. These birds will revisit these holes that they drill and lick the sap that flows from them.

Damage from pileated woodpeckers can be quite extensive. A single woodpecker can create this level of damage in a few days, or it may work at a tree throughout the season. Note the pile of large woodchips at the base of the tree.

Damage from pileated woodpeckers can be quite extensive. A single woodpecker can create this level of damage in a few days, or it may work at a tree throughout the season. Note the pile of large woodchips at the base of the tree.

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.

 

Tamarack mortality appearing in Marathon and Portage counties

Posted on by jodieellis

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

Woodpeckers strip bark off tamarack trees infested with eastern larch beetle, causing them to appear red. Photo by Mike Hillstrom

Woodpeckers strip bark off tamarack trees infested with eastern larch beetle, causing them to appear red. Photo by Mike Hillstrom

 

Foresters reported several new areas of tamarack mortality this winter in Marathon and Portage counties. The culprit continues to be eastern larch beetle (ELB). Although historically there have been periodic outbreaks of this native bark beetle, we have seen damage in Wisconsin every year since 1999. ELB initially attack stressed tamarack but, once in a stand, they often sweep through it over a few years even without additional stressors. The droughts of 2012-2013, defoliation by larch casebearer in 2014 and 2017, and prolonged flooding of stands in 2017 were all likely contributors to ELB infestations in central and northern Wisconsin. Infested stands should be salvage harvested and regenerated when possible, given the difficulty of accessing many tamarack stands.

 

Basswood bark “explosions” caused by Nectria cankers

Posted on by jodieellis

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

Many small Nectria cankers are present on this basswood tree.

Many small Nectria cankers are present on this basswood tree. Photo: Linda Williams

Winter is a great time to look for cankers on trees, so I thought I’d highlight one this month that you may have noticed but not recognized.  Most of you probably know Nectria as “the target canker” because growth patterns give the canker face a series of rings, expanding outwards as the canker ages, causing it to resemble a target. But on basswood, the cankers can appear very different at first glance.  On basswood, it may look like there are small “explosions” that occurred under the bark. The bark may be popped out a bit, may have oddly shaped outward growths, and it may or may not be clear that it’s hollow underneath the bark. When you peel away the outer bark and all the gnarly growths, you do end up with a typical Nectria canker face, but on basswood, you often have to dig to get to it. Accompanying photographs show the “bark explosion” appearance that you might notice, as well as what it looks like when you remove the bark.

Nectria cankers are perennial, meaning they grow a little each year. They are made of solid wood (not decayed wood unless another fungus has caused the damage). They typically have staining associated with them; this can cause degrade in lumber value of your final product.  If the cankers occur on small branches they can grow to girdle the branch, but the cankers found under the “bark explosions” on the main stem of basswood trees are not typically going to be able to cause that level of damage, and will instead simply continue to grow for many years.

Although this article focused on Nectria on basswood, the fungus can infect a number of other hardwood species. In those other species, you won’t find the “bark explosions” that you see on basswood, and instead will typically find a target shaped, open-faced canker.

Closer examination of one of the Nectria cankers on the basswood tree shown in the first photo. You can see how the bark appears to be “exploding” from the inside.

Closer examination of one of the Nectria cankers on the basswood tree shown in the first photo. You can see how the bark appears to be “exploding” from the inside. Photo: Linda Williams

Same canker as in the second photograph, starting to peel away the bark covering the canker face.

Same canker as in the second photograph, starting to peel away the bark covering the canker face. Photo: Linda Willliams

After removing the bark covering the canker, you can see the typical target-shaped canker formed by perennial growth of the fungus.

After removing the bark covering the canker, you can see the typical target-shaped canker formed by perennial growth of the fungus. Photo: Linda Williams

Another example of odd bark growth on basswood associated with Nectria canker.  These growths were very thick and solid, but underneath was a small Nectria canker.

Another example of odd bark growth on basswood associated with Nectria canker.  These growths were very thick and solid, but underneath was a small Nectria canker. Photo: Linda Williams

This cross section through a Nectria canker shows the staining that occurs in the tree due to Nectria.

This cross section through a Nectria canker shows the staining that occurs in the tree due to Nectria. Photo: Linda Williams

 

New finds of emerald ash borer in Wisconsin

Posted on by jodieellis

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

Emerald ash borer (EAB) continues to be found in new areas in Wisconsin, where EAB is tracked at the municipality and township levels. Recently, the insect was found for the first time in Eau Claire County, and there were additional finds in Dane, Dodge and Door counties where EAB is already established.

ounties shaded in tan are quarantined for EAB; this includes much of the southern half of  Wisconsin as well as other counties. Areas shaded in green represent the townships and municipalities where EAB has actually been identified, and show that not all counties that are quarantined are fully infested.

EAB quarantine map: counties shaded in tan are quarantined for EAB, green areas within counties depict townships and municipalities where EAB has been confirmed.

 

 

 

How did the cold snap over Christmas and New Year’s affect insects?

Posted on by jodieellis

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

Are you wondering how the bitterly cold weather we had in Wisconsin over Christmas and New Year’s affected the insects in your area? You’ll probably be disappointed to learn that, in general, our forest pests handle cold snaps just fine. Here are some examples of what it would take to have an impact on some of our insect pests: 

Gypsy moth: Well, it depends. If egg masses were covered by snow (either near the ground or on branches), they were protected from the cold temperatures. If egg masses were exposed, according to a study done in Michigan, it would take several days of temperatures lower than -15 °F to start seeing mortality in eggs. The more days eggs spend below that temperature, the more mortality, although super-cooled eggs or eggs covered by snow can withstand much lower temperatures and survive. 

Forest tent caterpillar eggs form a band around an aspen twig. The protective hairs coating the eggs have been removed to show the eggs. Photo: Linda Williams

Forest tent caterpillar eggs form a band around an aspen twig. The protective hairs coating the eggs have been removed to show the eggs. Photo: Linda Williams

Forest tent caterpillar: This native insect enjoys our northern climes, so it should be no surprise that it handles the cold quite well. One study found that at temperatures below -45 °F, there was significant mortality. The egg masses of forest tent caterpillars are found near the tips of branches, which are not typically covered with snow. 

Spruce budworm: As with forest tent caterpillar, this native insect thrives in the cooler regions of North America and temperatures lower than -40 °F are required to see any mortality. 

Emerald ash borer: You may recall in 2014, when we also had bitterly cold temperatures, there was quite a media furor about EAB mortality and some research that was going on in Minnesota. Everyone was hoping EAB would be killed completely in those cold areas. Although some mortality did occur, researchers found that because EAB larvae and pre-pupae are protected under the bark of the tree, temperatures need to be drastically low, or very low for a certain number of days, to see significant mortality. That being said, EAB mortality can occur at temperatures below -13 °F, and, if enough mortality occurs, the spread of the population may be slowed as it has to rebuild from the few individuals that survived the bitter cold. 

Multicolored Asian ladybeetles cluster together in protected places to wait out the cold. 

Multicolored Asian ladybeetles cluster together in protected places to wait out the cold. Photo: Linda Williams

Household pests like ladybugs and flies:  Those kinds of insects find protected places to spend the winter (sometimes in your house!), and although there can be significant mortality outside, there will be many that survive the cold just fine.  They often find protected places that are slightly warmer than ambient air temperatures. 

Ticks:  Wood ticks and deer ticks overwinter on the ground, under snow, so in areas of the state where there is plenty of snow cover, they’re doing fine so far.  Desiccation is usually a much more important problem during the life of a tick than overwintering cold. 

Some insects seem to enjoy winter weather, like snowfleas (also known as collembolans or springtails), and winter cutworm, both of which can be found crawling on snow during warmer winter days. 

How can insects survive winter? Different types of insects overwinter during different life stages.  Some insects overwinter as eggs, because eggs are often quite resistant to desiccation, can have “hairs” covering them, are laid in protected areas, or inserted into needles/bark/etc. to give even more protection.  Some adult and larval insects survive winter by supercooling, which is a process in which they eliminate water molecules from their bodies (which, if left behind, could create deadly crystals in their systems).  Supercooling is the equivalent to using antifreeze, allowing the insects to survive very cold temperatures.  One problem insects can have is when there is a warm-up followed by a sudden cold snap, a situation which also causes problems for trees.  When we have steady cold temperatures, insects tend to just hang out like we do, waiting for spring.