Statewide Forest Health

Forest tent caterpillar egg mass surveys indicate low populations again

Newly hatched forest tent caterpillars with the egg mass they emerged from. Egg masses are laid in mid-summer and remain on the tree through the winter.

Newly hatched forest tent caterpillars with the egg mass they emerged from. Egg masses are laid in mid-summer and remain on the tree through the winter.

Low numbers of forest tent caterpillar egg masses were found recently during surveys in Vilas and Oneida Counties. Forest tent caterpillar is a native insect that has periodic outbreaks. Our last outbreak was from 1999-2002, and they typically have outbreaks every 10-15 years. Last year I noticed a few more caterpillars than the previous year, but there was no noticeable defoliation. So far egg mass surveys indicate another year of low populations, although there may be areas with locally higher populations. Forest tent caterpillar eggs will start hatching soon, timed to closely match the emergence of aspen leaves.

Eastern tent caterpillars hatch from eggs and immediately start to create a web nest. Young caterpillars are shown on a small web nest.

Eastern tent caterpillars hatch from eggs and immediately start to create a web nest. Young caterpillars are shown on a small nest.

Eastern tent caterpillars do not follow a typical outbreak pattern and tend to be present at some low level every year. They create web nests early in the spring, preferring black cherry trees, crabapple trees, or other stone fruits. When webs are small the caterpillars can be easily crushed or sprayed. As webs get bigger you may have to use a rake to pull them out of the tree. It is not necessary to prune the branch out of the tree. Doing so will actually cause more damage to the tree than the defoliation caused by the caterpillars, because trees can more easily send out additional leaves than grow a branch to replace one you prune out. Please do not burn nests out of the trees as this could start a wildfire. 

 

Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@wisconsin.gov), 920-662-5172.

 

Emerald ash borer new locations in Wisconsin

EAB quarantine map. Counties shaded in tan are quarantined for EAB, and includes much of the southern half of Wisconsin, as well as other counties. Areas shaded in green are the townships and municipalities where EAB has actually been identified, and shows that not all counties that are quarantined are fully infested.

EAB quarantine and detections map. Counties shaded in tan are quarantined for EAB, green areas are townships and municipalities where EAB has actually been identified.

Emerald ash borer (Agrilus planipennis) continues to be found in new areas. Wisconsin continues to track EAB at the municipality or township level; quarantined counties are shown in tan and known infested areas are shown in green on the map.

If you know you have EAB, please contact us with that information so we can verify the infestation and update the maps. If your area:

  • is not shaded in green on the map please contact DNR or
  • is not shaded at all on the map please contact DATCP.

You can reach both agencies from the menu options when you call 1-800-462-2803.

New county quarantines

  • none

New finds in counties already quarantined

  • Adams/Columbia/Juneau/Sauk counties — city of Wisconsin Dells
  • Brown County — village of Allouez
  • Crawford County – town of Bridgeport
  • Columbia County – town of Lowville
  • Columbia/Dodge counties – village of Randolph
  • Dane County – village of DeForest
  • Green County – town of Monroe
  • Jackson County — towns of Melrose and North Bend
  • Jefferson County – towns of Aztalan, Farmington, Hebron, and Sumner
  • La Crosse County – town of Shelby
  • Monroe County – city of Sparta
  • Rock County – towns of Clinton, Harmony, Johnstown, and Lima
  • Sheboygan County – village of Kohler
  • Trempealeau County — towns of Ettrick, Gale and Preston

 Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@wisconsin.gov), 920-662-5172.

 

Emerald ash borer trapping in 2017

The Wisconsin DNR forest health team is planning to trap for emerald ash borer (EAB) at 20 locations in 2017.

Emerald ash borer traps will be placed at 12 locations in northwest Wisconsin in 2017: Big Bay State Park, Amnicon Falls State Park, Pattison State Park, Brule River State Forest, Governor Knowles State Forest, Interstate State Park, Willow River State Park, Eau Claire, Smith Lake County Park, Flambeau River State Forest, Big Falls County Park, and Pershing State Wildlife Area.

EAB trap locations in northwest Wisconsin in 2017.

Emerald ash borer traps will be placed at 8 locations in northwest Wisconsin in 2017: Northern Highlands American Legion State Forest, Governor Thompson State Park, Hartman Creek State Park, Poygan Marsh Wildlife Area, River Side Park, Princeton, Dodge Memorial Park, and Grand River Marsh Wildlife Area.

EAB trap locations in northeast Wisconsin in 2017.

Traps will mostly be placed on state properties. A couple traps will be placed on county land where state properties are not in the local area. Traps are deployed close to 400 growing degree days so they are ready when EAB adults start emerging at approximately 450 degree days. In 2016, southern Wisconsin hit 450 degrees days (modified base 50°F) in late May.

Written by: Mike Hillstrom, forest health specialist, Wisconsin Dells (Michael.Hillstrom@Wisconsin.gov), 715-459-1371.

Lesser celandine is an emerging threat to Wisconsin forests – be on the lookout.

Spherical bulbils of lesser celandine form during the spring growing season. Later they drop off and sprout to form new plants.

Spherical bulbils of lesser celandine form during the spring growing season. Later they drop off and sprout to form new plants.

Lesser celandine (Ranunculus ficaria), also known as fig buttercup, is a ground layer plant and an aggressive invader of forests in North America. So far, it is relatively unknown in Wisconsin but has been found in the southeastern part of the state, especially in moist (mesic and wet-mesic) forests and along river banks.

Lesser celandine is a spring ephemeral that emerges in early spring, develops flowers, dies back by early summer, and remains dormant in underground tubers. During the short growing period the plant produces bulbils which sprout and give rise to new plants. After the round bulbils drop off they are spread by gravity, water, small animals, and like the tubers, transported when soil is moved. Continue reading “Lesser celandine is an emerging threat to Wisconsin forests – be on the lookout.”

Welcome to the new Forest Health News

The DNR Forest Health Program has transitioned to a new online newsletter format. You will no longer receive Pest Updates and Regional Forest Health Newsletters directly from DNR Forest Health Specialists. Instead, if you are subscribed to Forest Health News you will receive an email, typically once per month, when new information is posted by the Forest Health Program on this new Wisconsin DNR Forestry News site. You can also access the articles directly anytime.

If you haven’t already, consider subscribing and please take a moment now to include widnr@service.govdelivery.com in your email address book, so the emails avoid your spam box.

Monthly emails will have Forest Health articles organized by:

  • Information that is relevant statewide and
  • Information specific to certain parts of the state.

The Forest Health News zones have changed too, so check out which counties each zone covers.

Continue reading “Welcome to the new Forest Health News”

New zones for Forest Health News updates

The map shows which counties are included in each Forest Health News zone for purposes of monthly news updates, as of March 2017. Subscribers to Forest Health News emails and visitors to this site who are interested in forest health articles for specific parts of the state can refer to the map to check out which forest health zone or region they’d like to read news updates from on this site. If you use tags from the menu bar on the right side of this page to sort articles remember: Forest Health News with statewide relevance is shown with a “Statewide Forest Health” tag and is not included in each zone’s tag.

For more information: Colleen Robinson, forest health educator (Colleen.Robinson@Wisconsin.gov), 608-266-2172.  

Oak wilt found in Price County, plus prevention steps

This map shows the known distribution of oak wilt in Wisconsin by county and townships as of December 1, 2016.

Map of the known distribution of oak wilt in Wisconsin as of December 1, 2016.

Oak wilt, a deadly fungal disease affecting red oaks, was confirmed for the first time in Price County in 2016. In addition to the new county find, the disease was also confirmed in various townships in northern Wisconsin counties where we already knew oak wilt was present.

The map in the oak harvesting guidelines was updated based on the find.

Oak wilt is commonly found in the southern two-thirds of the state, but has been creeping northward. The disease was found for the first time in 2010 in Oneida County, in 2012 in Lincoln, Sawyer, and Vilas counties, in 2013 in Rusk County, and in 2014 in Washburn County. Oak wilt has been confirmed in all Wisconsin counties except Ashland, Bayfield, Calumet, Door, Douglas, Forest, Iron, Kewaunee, Manitowoc, Sheboygan, and Taylor.

Read more about oak wilt prevention in the news release from March 21, 2017: Protect oak trees from oak wilt by waiting until after July to prune.

Written by: Kyoko Scanlon, forest pathologist, Fitchburg (Kyoko.Scanlon@Wisconsin.gov), 608-275-3275.

Oil or remove gypsy moth egg masses now

Gypsy moth egg masses are tan colored lumps about the size of a nickel or a quarter. They are usually found on trees but may also be found on outdoor articles such as firewood piles, bird houses and picnic tables.

Gypsy moth egg masses.

Homeowners who are interested in reducing gypsy moth caterpillar numbers this summer should consider oiling or removing reachable egg masses well before the eggs begin hatching in the second half of April. Gypsy moth egg masses are tan-colored lumps about the size of a nickel or quarter, and usually contain 500 to 1,000 eggs. The egg masses can be found on any rough or protected surface including trees, houses, firewood piles, bird houses and other outdoor objects. Do NOT scrape the egg masses onto the ground or step on them or break them apart. Many of the eggs will survive and still hatch.

Continue reading “Oil or remove gypsy moth egg masses now”

Treat your ornamental ash trees for emerald ash borer this spring

A yellow ornamental ash tree at peak fall color. This tree is worth treating to protect it from being killed by emerald ash borer.

High-value ash tree at peak fall color.

March is a good month to consider insecticide treatments for high-value ornamental ash trees this spring. Emerald ash borer (EAB) has been found in 42 Wisconsin counties and is expected to be more than 99% fatal to ash trees that are not protected with insecticide every 1-2 years. Many insecticides used in EAB treatments are applied between mid-April and mid-May, and now is a good time to contact a tree service or other pesticide application business if arranging for professional insecticide treatments.

Property owners with susceptible ash trees should consider a number of factors when deciding to treat their ash trees, including financial cost, tree condition and location, the shade a tree provides, its contribution to property values, and aesthetic view. Homeowners should also consider the financial cost of removing a tree that is killed by EAB, and the benefits that a dead tree no longer provides.

Continue reading “Treat your ornamental ash trees for emerald ash borer this spring”

Emerald ash borer new locations in Wisconsin

Emerald ash borer (Agrilus planipennis) continues to be found in new areas. Regional Forest Health Updates were not sent during the 2016/2017 winter, so the list below includes new EAB finds from the last few months. Wisconsin continues to track EAB at the municipality or township level; infested areas are shown in green on the map below. If you know you have EAB please contact us with that information so we can verify the infestation and update the maps. If your area:

  • is not shaded in green on the map please contact DNR or
  • is not shaded at all on the map please contact DATCP.

You can reach both agencies from the menu options when you call 1-800-462-2803. Continue reading “Emerald ash borer new locations in Wisconsin”