Forest Health News

2018 Forest Health Annual Report now available

Posted on by margueriterapp

The Forest Health Annual Report summarizes notable impacts pests, diseases and weather on the health of Wisconsin’s forests. The report is a collaborative product written by DNR forest health specialists from around the state. It outlines the damage and spread of both native and invasive pests and diseases during that year and puts these into context of observations from previous years. Management programs and their results are also described. Highlights from the 2018 annual report include:

  • American beech with resistance to disease-causing scale insect entered into a breeding program for species conservation and reintroduction
  • Confirmation of jumping worms in northern counties
  • Biological control of emerald ash borer
  • Closure of the state gypsy moth suppression program
  • Innovation in survey of the invasive plant lesser celandine
  • Dieback and mortality in balsam fir caused by freezing weather in April followed by unseasonably hot temperatures in early May

The 2018 report and others dating back to 2003 are available on the forest health publications page. Historical reports dating back to 1951 are archived and available upon request. Contact Marguerite Rapp at marguerite.rapp@wisconsin.gov for more information on the archived reports.

Jack pine budworm not likely an issue in 2019

Posted on by margueriterapp

By Todd Lanigan, forest health specialist, Eau Claire, Todd.Lanigan@wisconsin.gov, 715-210-0150. 

No caterpillars or egg masses were found in the 2018 jack pine budworm surveys. Done in the spring for caterpillars and the fall for egg masses, surveys help predict jack pine budworm defoliation in the coming year. Surveys were conducted in the west central part of the state, covering portions of Dunn, Eau Claire, Jackson, Monroe, Pierce and St. Croix counties. 

Jack pine budworm caterpillar on spruce needle tip.

Caterpillars emerge in the spring and feed on host tree foliage. 

Cluster of jack pine budworm eggs on tip of spruce needle.

Egg masses are deposited on the tips of host tree foliage. 

In Wisconsin, jack pine budworm feeds on all native species of pine: jack, red and white. It is occasionally found on white spruce, but this has only been documented where spruce trees were located near an infested pine plantation.

Jack pine budworm regularly cycles from low to high populations, with outbreaks occurring every 8-10 years on average. During an outbreak, defoliation from these caterpillars can be widespread and lead to growth loss, topkill and tree mortality.

Three host trees showing severe defoliation and mortality due to jack pine budworm defoliation.

During a jack pine budworm outbreak, defoliation and mortality can be severe.

Wisconsin forests are overdue for an outbreak, with the last one occurring from 2005-2009, but annual surveys indicate that populations of jack pine budworm are still low enough to be undetected. Based on the 2018 surveys, jack pine budworm should not be a problem in 2019.

Dispose of wreaths properly to avoid spreading invasive insect

Posted on by Kirsten Held

image of elongate hemlock scale The small brown blotches on the underside of these needles are an invasive species found on some holiday decorations purchased from chain stores in 2018. Help prevent the spread of elongate hemlock scale by properly disposing of wreaths, swags and other potentially infested materials. (Photo credit: WI Dept. of Ag, Trade & Consumer Protection)

Please remember to properly dispose of wreaths, trees and other holiday decorations from chain stores that may be infested with an invasive insect.

If you purchased any holiday wreaths, swags, boughs and other arrangements from chain stores, please dispose of them by burning or bagging them and putting them in the trash as they may be infested with an aggressive invasive insect that can harm Wisconsin’s native forests, Christmas tree farms, and even ornamental conifers in your yard.

During this recent holiday season, Department of Agriculture, Trade and Consumer Protection (DATCP) inspectors found an invasive insect pest from Asia called elongate hemlock scale (EHS) on holiday wreaths, swags and boughs, and in arrangements of evergreen boughs in hanging baskets, porch pots, mugs and sleighs.

These items came from suppliers in states where EHS is already established. This insect poses a risk to Christmas tree fields as well as native and ornamental coniferous trees in Wisconsin. To prevent the introduction of EHS to Wisconsin, DATCP officials are asking those who purchased the listed decorative items from chain stores in 2018 to properly dispose of them.

Trapping project found no non-native beetles

Posted on by margueriterapp

By Mike Hillstrom, forest health specialist, Fitchburg. Michael.Hillstrom@wisconsin.gov; 608-513-7690

The Wisconsin DNR’s forest health team received funding to trap for non-native beetles in 2018. This project was funded by the US Forest Service through an Early Detection and Rapid Response (EDRR) grant. The project is complete, and we happily share that we did not find any non-native beetles!

Forest health staff member Scott Schumacher is hanging a Lindgren funnel trap (12 funnels stacked to look like a tree trunk) from a tree branch to survey for non-native beetles.

Forest health staff member Scott Schumacher hangs a Lindgren funnel trap to survey for non-native beetles.

The Forest Service periodically provides funding to states to trap for non-native bark and ambrosia beetles. The goal of trapping is to detect, delimit and monitor newly introduced exotic beetles and to quickly assess and respond to newly detected infestations.

We placed traps at 12 high-risk sites in Jefferson, Waukesha, Milwaukee, Racine, Manitowoc, and Brown counties. Sites were selected in collaboration with the Wisconsin Department of Agriculture, Trade and Consumer Protection and were based on proximity to large commercial port entries on Lake Michigan or recycling facilities for pallets and other waste packaging. Three Lindgren funnel traps (12 funnels stacked to look like a tree trunk) and lures were assembled at each site and checked every two weeks between early May and early August. Specimens collected from the traps were sent to a Forest Service taxonomist for identification.

New northern oak wilt detections

Posted on by margueriterapp

By Paul Cigan, forest health specialist, Hayward. Paul.Cigan@wisconsin.gov; 715-416-4920 and Linda Williams forest health specialist, Woodruff. Linda.Williams@wisconsin.gov; 920-360-0665

Oak wilt (OW) was confirmed for the first time in Bayfield and Douglas counties and in 16 new northern townships in 2018. The new OW infections occurred on a range of properties, including county, tribal, private, U.S. Forest Service and Board of Commissioners of Public Lands. Wisconsin Department of Natural Resources (DNR) forest health staff are working proactively with affected property managers and landowners to address these infections and prioritize disease prevention and detection in the future.

 

Oak wilt distribution map. Confirmed counties are displayed in red. Confirmed townships are displayed in pink 6-mile square blocks.

The greatest risk of overland transmission in northern Wisconsin is from April 15 to July 15, when fungal spores readily infect open wounds. Most of these new cases occurred during this time frame due to stem and branch damage. The primary causes of damage were roadside brush clearing, pruning, lot clearing and storm-caused branch breakage. Fungal spores may have come from diseased oak firewood and unprocessed wood recently transported into these areas.

Image shows a group of oak trees. Northern red oak on far left is in wilting stage of disease (leaves on but wilting and dropping). Oak on far right has mechanical root collar injury. Dairyland Township, Douglas County.

OW disease center. Oak on far left was infected through belowground root contact with tree damaged in lot clearing (far right). Dairyland Township, Douglas County (photo taken by Paul Cigan).

If oak wilt is present in or within 6 miles of the county where you manage oak, your management activities may be affected by seasonal harvesting restrictions to reduce OW introduction and impact. Read DNR’s oak harvesting guidelines for more information and refer to the list below of new 6 square mile blocks by township and county to see if OW has been detected near your property.

Bayfield County
Barnes T45N R9W
Cable T43N R7W
Drummond T45N R8W
Douglas County
Dairyland T43N R15W
Gordon T44N R11W
Langlade County
Elcho T34N R11E
Langlade T33N R13E
Neva T32N R11E
Sawyer County
Couderay T39N R8W
Hayward T41N R8W
Hunter T40N R7W
Round Lake T41N R8W
Spider Lake T42N R7W
Vilas County
Boulder Junction T42N R6E
Lac du Flambeau T41N R5E, T40N R5E
St. Germain T40N R8E

Please report any suspected oak wilt infections to your local DNR forester or regional forest health specialist and learn more about oak wilt identification and biology on the DNR oak wilt webpage. To learn more about firewood rules and how you can help reduce transmission of pests and diseases, including oak wilt, visit the DNR firewood page.

10 oak leaves lain on downed log display bronze discoloration typical of oak wilt. Midrib and base of leaf are still green.

Bronzed leaves fallen from infected oak. Leaves were observed beneath infected northern red oak. Cable Township, Bayfield County (photo taken by Paul Cigan).

Heterobasidion root disease in Monroe County

Posted on by margueriterapp

By Todd Lanigan, forest health specialist, Eau Claire. Todd.Lanigan@wisconsin.gov; 715-210-0150

Heterobasidion root disease (HRD), formerly known as annosum root rot, was recently found in Monroe County for the first time in the town of Little Falls. With this detection, HRD is now known to occur in 28 Wisconsin counties.

HRD distribution map. Counties where HRD is present are shown in blue with most recently confirmed county shown in dark blue.

Fruiting bodies of the pathogen, Heterobasidion irregulare, were found on dead overstory red pine and both live and dead white pine saplings in the Big Creek Fishery Area. The 20-acre stand was a red pine plantation established in 1958 and last thinned in 2012. Wood samples were collected to isolate and identify the pathogen through microscopic identification at the Forest Health Lab in Fitchburg.

Image of multiple spores viewed under microscope. Conidiophores look like Q-tip heads.

Microscopic spores isolated from wood samples and confirmed as HRD in Forest Health Lab.

Based on this new find, a number of townships were added to the 25-mile buffer zones used in determining appropriate management activities according to the HRD Management Guide. There will be a one-year grace period for implementation of the guide in these townships.

The Forest Health Program has records of all confirmed HRD detections. If you suspect this disease is present in a stand, contact your regional forest health specialist.

For more information about HRD, visit the DNR Forest Health webpage.

Pesticide applicator training offered in 2019

Posted on by Ellen Clark

By Kyoko Scanlon, forest pathologist, Fitchburg, Kyoko.Scanlon@Wisconsin.gov, 608-235-7532

Wisconsin Pesticide Applicator Training (PAT) Program with University of Wisconsin Extension is offering one training session for Forestry (Category 2.0) in 2019. The training is a one-day indoor session to review the materials in the training manual. A certification exam will be administered at the end of the day by Wisconsin Department of Agriculture, Trade and Consumer Protection.

The PAT Forestry training day is scheduled for January 24, 2019 at the Marathon County Extension Office in Wausau. Preregistration is required and costs $30. For more information and to register, visit the Pesticide Applicator Training website.

 

ALB: What to watch for in Wisconsin

Posted on by Ellen Clark

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

We do NOT have Asian longhorned beetle (ALB) in Wisconsin at this time, but it’s good to be on the lookout for it. Every year folks submit reports of insects that they suspect to be ALB, but to date they have always been confirmed as the native whitespotted sawyer (sometimes called pine sawyer), which attacks stressed conifers rather than the maple and other hardwood species preferred by ALB. If you find a beetle that you suspect to be ALB, please collect the beetle, take some pictures, and send them to your forest health specialist, or to the University of Wisconsin Insect Diagnostic Lab for identification.

Asian longhorned beetle is a large beetle. They are smooth and shiny black with white spots and blotches on their wing covers. Photo by Joe Boggs, Ohio State University, bugwood.org

Asian longhorned beetle is a large beetle. They are smooth and shiny black with white spots and blotches on their wing covers. Photo by Joe Boggs, Ohio State University, bugwood.org.

 

Our native pine sawyer beetle appears dusty or pitted, but is often mistaken for Asian longhorned beetle. Photo by Linda Williams.

Our native pine sawyer beetle appears dusty or pitted, but is often mistaken for Asian longhorned beetle. Photo by Linda Williams.

ALB can be a very destructive pest. It is typically introduced, unintentionally, to new areas via wooden pallets, wood packing materials, or firewood. The Don’t Move Firewood website has some great tips for safe transport of firewood, how to find firewood locally, as well as a list of other invasive insects and diseases to be aware of when buying or using firewood.

USDA APHIS, which conducts eradication efforts wherever ALB is found, recently announced that an area of Ohio was officially ALB-free, and the quarantine was subsequently removed. Earlier this year in March, a separate area of Ohio was also declared ALB-free. That leaves just one area of Ohio with ALB quarantines still in effect. Eradication of ALB can take decades to complete and involves extensive efforts including tree removal and chemical treatments. States with current ALB quarantines include: Massachusetts, New York and Ohio.

For more info on ALB, check out the USDA APHIS ALB webpage, and as always, please let us know if you think you have come across a forest health concern, including ALB.

Invasive stink bug numbers increasing

Posted on by Ellen Clark

By Mike Hillstrom, forest health specialist, Fitchburg. Michael.Hillstrom@wisconsin.gov; 608-513-7690

Invasive brown marmorated stink bugs (BMSB) are now well established and reproducing in southern and central Wisconsin. This fall we are getting our first reports of large numbers of BMSB gathering on the sides of houses looking for places to overwinter. This problem will continue to get worse as stink bug populations increase and their range expands. Damage to important crops, ornamental plants and trees will also be a major concern. BMSB is known to feed on a wide variety of plants including apples, tomatoes, corn, soybeans, silver maple and walnut.

Adult brown marmorated stink bugs are ½ to ¾ inch long, brown with alternating white and black patches on the edge of the abdomen and white bands on the antennae and have smooth shoulders that lack spines.

An adult brown marmorated stink bug. Photo by P.J. Liesch, University of Wisconsin Insect Diagnostic Lab.

Researchers are working on ways to manage the pesky bugs. One new method being explored is hanging black netting soaked in insecticide at locations where the bugs congregate, such as doors on the north and east sides of structures.

Samurai wasps are another promising lead. These stink bug-killing wasps found their way into the U.S. on their own over the past few years, but researchers are also working with lab-reared samurai wasps that they hope to release. Samurai wasps parasitize the eggs of BMSB but do not sting humans or other animals.

For more information about identification and management check out:
• University of Wisconsin-Extension
• WisContext
• Midwest Stink Bug app

EAB biological control recoveries

Posted on by Ellen Clark

By Bill McNee, forest health specialist, Oshkosh. bill.mcnee@wisconsin.gov; 920-360-0942

Tetrastichus planipennisi, an introduced, parasitic wasp that attacks emerald ash borer (EAB) larvae, was successfully recovered at two sites in Racine and Waukesha counties in October 2018. This was the first recovery of the natural enemy from Waukesha County. These events indicate that the wasps, released at the same sites in 2015, successfully established and have been attacking EAB larvae since then. This wasp species was previously recovered at release sites in six southeast Wisconsin counties (Kenosha, Milwaukee, Ozaukee, Racine, Walworth and Washington). These releases began in 2011 to reduce EAB populations over the long term, so that some small ash trees might reach reproductive maturity, thus allowing ash to persist on the landscape, albeit as a smaller, less common tree. The tiny wasps do not sting or bite people, and the public is unlikely to ever see them.

Adult Tetrastichus planipennisi wasp shown on a finger. Photo by Bill McNee.

Tree bark samples from the two sites are currently being incubated to look for another parasitic wasp, Oobius agrili, that may be present in EAB eggs. This species has not been recovered in prior surveys and is known to be more difficult to detect than T. planipennisi. Recovery surveys will continue at many locations 2-3 years after wasps are released to allow the populations of introduced parasitoids to increase to detectable levels.

It is important to note that insecticide treatment of high-value ornamental trees still needs to be done to prevent tree mortality from EAB. For more information about EAB, parasitoid wasps, and insecticide treatments, visit http://www.emeraldashborer.wi.gov.

Cluster of Tetrastichus pupae (circled) from a parasitized EAB larva, located near an unparasitized EAB larva. Photo by Bill McNee in Racine County, October 2018.