Squirrels Love Acorn Pip Galls And Weevils

Posted on by akabelowsky

By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665

Closeup photo of six acorns. One still has pip galls; the others have had their pip galls eaten by squirrels.

The acorn farthest on the right has pip galls. Squirrels ate the pip galls from the other acorns. / Photo Credit: Linda Williams, Wisconsin DNR

Several areas in northern Wisconsin have reported significant acorn drop. In almost all cases, these acorns have been damaged by either pip galls or acorn weevils.

Squirrels enjoy feeding on pip galls and will pluck those acorns off the tree, rip off the cap, eat the pip gall and drop the rest of the acorn to the ground. Squirrels will also seek out acorns infested by acorn weevils. They will open those acorns, eat the larvae and then drop the rest of the acorn to the ground.

Continue reading “Squirrels Love Acorn Pip Galls And Weevils” →

Which Thistle Is This Thistle?

Posted on by akabelowsky

By Erika Segerson-Mueller, DNR Invasive Plant Program Specialist, Oshkosh Service Center;
erika.segersonmueller@wisconsin.gov or 715-492-0391

With 10 thistle species present in Wisconsin, it can be tricky to determine which thistle is which. You may be tempted to control every thistle you see, assuming all types are invasive. But Wisconsin also has native thistles that provide valuable habitat and food for small birds and butterflies.

Thistles are either biennials (following a two-year life cycle) or perennials (regrowing every spring). They have lobed, spiny leaves and sometimes spiny stems. Thistles have composite flowers, with each flowerhead being composed of many tiny flowers, or florets.

Read on a for an overview of invasive thistles found in Wisconsin so you can stop wondering: Which thistle is this thistle? Continue reading “Which Thistle Is This Thistle?” →

CISMA Events For August, September

Posted on by akabelowsky

By Erika Segerson-Mueller, DNR Invasive Plant Program Specialist, Oshkosh Service Center;
erika.segersonmueller@wisconsin.gov or 715-492-0391

A chart showing Wisconsin's different Cooperative Invasive Species Management Areas boundaries.When it comes to fighting invasive plants, Wisconsin’s CISMAs (Cooperative Invasive Species Management Areas) are often the first line of defense (and offense). These regional groups provide a localized resource for landowners looking for invasive plant education, identification support and assistance with controlling invasives on their properties. Continue reading “CISMA Events For August, September” →

New Invasive Pest Discovered In Wisconsin

Posted on by akabelowsky

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

A closeup of an elm zigzag sawfly caterpillar consuming a leaf. The invasive insect, new to Wisconsin, was found on an elm tree near the Wisconsin Department of Natural Resources office in Oshkosh on July 16, 2024.

A closeup of an elm zigzag sawfly caterpillar consuming a leaf. The invasive insect, new to Wisconsin, was found on an elm tree near the Wisconsin Department of Natural Resources office in Oshkosh on July 16, 2024. / Photo Credit: Bill McNee, Wisconsin DNR

The invasive insect elm zigzag sawfly (Aproceros leucopada) has been detected in Wisconsin for the first time.

Following the initial Wisconsin discovery in Portage County on July 4. Through Aug. 12, the pest has since been detected in 17 Wisconsin counties. Continue reading “New Invasive Pest Discovered In Wisconsin” →

Larch Casebearer Damage Spotted In North

Posted on by akabelowsky

By Paul Cigan, DNR Forest Health Specialist, Hayward;
Paul.Cigan@wisconsin.gov or 715-416-4920

Photo showing a tamarack tree branch with severe needle mining from larch casebearer. / Photo Credit: Paul Cigan, Wisconsin DNR

A tamarack branch shows severe needle mining from larch casebearer. / Photo Credit: Paul Cigan, Wisconsin DNR

Larch casebearer has caused localized heavy defoliation in some tamarack swamps in central Burnett County this spring, causing tamarack to stand out with a stark appearance of bright-brown foliage by mid-June.

Larvae of this exotic moth damage tamarack needles by “mining” the inner needle tissue. Heavily damaged tamarack progress in color from pale green to yellow and eventually turn a bright, reddish brown as needles dry out and die.

 

 

Continue reading “Larch Casebearer Damage Spotted In North” →

Spruce Budworm Defoliation Continues

Posted on by akabelowsky

By Linda Williams, DNR Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov or 920-360-0665

Closeup photo showing that webbing created by the spruce budworm caterpillar holds needles and frass and protects the caterpillar. A pupa hangs from the branch.

Webbing created by the spruce budworm caterpillar holds needles and frass and protects the caterpillar. A pupa hangs from the branch. / Photo Credit: Linda Williams, Wisconsin DNR

Although symptoms weren’t as prevalent as in 2023, this year marked yet another year of defoliation from spruce budworm.

Another severe year of defoliation causes additional stress on the trees. Even though there has been a lot of rainfall this spring, it’s still stressful for the trees to face repeated years of defoliation by spruce budworm before they begin to decline and die.

Continue reading “Spruce Budworm Defoliation Continues” →

Dropping Leaves May Indicate Oak Wilt

Posted on by akabelowsky

By Linda Williams, DNR Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov or 920-360-0665

Photo showing that oak leaves that drop from a tree infected with oak wilt may be all brown or all green, or often they will have green near the base of the leaf and the outer portions will be brown or watersoaked green.

Oak leaves that drop from a tree infected with oak wilt may be all brown or all green, or often they will have green near the base of the leaf and the outer portions will be brown or watersoaked green. / Photo Credit: Linda Williams, Wisconsin DNR.

The middle of summer is the time to start watching oak trees for symptoms of oak wilt. Although symptoms show up suddenly and leaves drop quickly, symptoms can emerge anytime between now and when leaves turn color in the fall.

Trees that were wounded in the spring and became infected with the fungus that causes oak wilt will usually die that same year. In established oak wilt pockets, the fungus moves underground through grafted root systems and trees will wilt as the fungus moves into the tree.

Continue reading “Dropping Leaves May Indicate Oak Wilt” →

Tubakia Leaf Disease Affects Red Oak

Posted on by akabelowsky

By Linda Williams, DNR Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov or 920-360-0665

A tree showing that lower branches are thin and have lost leaves due to Tubakia leaf spot, while leaves on its upper branches look good.

A tree showing that lower branches are thin and have lost leaves due to Tubakia leaf spot, while leaves on its upper branches look good. / Photo Credit: Linda Williams, Wisconsin DNR.

Tubakia leaf spot is a leaf disease caused by a fungus (Tubakia dryina) that typically affects the lower canopy of red oaks.

Because of all the rain that came during the spring and early summer of 2024, the fungus has started to impact some trees. Problems didn’t occur last year because the weather was too dry.

Continue reading “Tubakia Leaf Disease Affects Red Oak” →

Emerald Ash Borer Confirmed In All 72 Counties

Posted on by akabelowsky

By Art Kabelowsky, DNR Outreach and Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov; 608-335-0167

Closeup photo of an adult emerald ash borer. The pest has been detected in Burnett County, making it the 72nd and final county in Wisconsin that have confirmed presence of the invasive insect.

The emerald ash borer has been detected in Burnett County, making it the 72nd and final county in Wisconsin that have confirmed presence of the invasive insect. / Photo Credit: Paul Cigan, Wisconsin DNR

Sixteen years after the Wisconsin Department of Natural Resources (DNR) first detected emerald ash borer (EAB) in Wisconsin, the invasive beetle has been found in the last county without a previous detection.

Burnett County, in northwest Wisconsin, is the 72nd and final county to have a detection of the tree-killing pest.

Continue reading “Emerald Ash Borer Confirmed In All 72 Counties” →

UW Madison Extension Urban Forestry Workshop: Bare Root Trees And Gravel Beds

Posted on by janness

Join us for a two-part workshop on the value and uses of bare root trees and how to use gravel beds to hold and maintain bare root stock before it is planted. Part one will be delivered via Zoom on Friday, Sept. 20. Part two will be an in-person field day visit to an operating gravel bed. You will select one of the six locations around the state during registration. ISA CEUs will be available for both parts.

The cost of the workshop is $30, and the registration deadline is Sept. 12. Continue reading “UW Madison Extension Urban Forestry Workshop: Bare Root Trees And Gravel Beds” →