Northern WI Forest Health

Forest Health Staff To Join Oak Disease Webinar

Posted on by akabelowsky
A screen grab of a webpage on the United States Environmental Protection Agency website discussing a pest management webinar set for Dec. 10, 2024.

The U.S. Environmental Protection Agency will present an international webinar titled “Deadly Oak Diseases” from 1 to 2:30 p.m. Tuesday, Dec. 10. / Graphic Credit: U.S. Environmental Protection Agency

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg;
Michael.Hillstrom@wisconsin.gov

The U.S. Environmental Protection Agency (EPA) will present an international webinar titled “Deadly Oak Diseases” from 1 to 2:30 p.m. (CST) Tuesday, Dec. 10.

Continue reading “Forest Health Staff To Join Oak Disease Webinar” →

Check Conifers For Invasive Adelgids

Posted on by akabelowsky
Photo showing white, cottony hemlock woolly adelgid egg sacs on a hemlock branch.

White, cottony hemlock woolly adelgid egg sacs on a hemlock branch. / Photo Credit: Bill McNee, Wisconsin DNR

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg; Michael.Hillstrom@wisconsin.gov

Hemlock woolly adelgid (HWA) and balsam woolly adelgid (BWA) are invasive, aphid-like insects that cause tree mortality in North America. Neither has been found in Wisconsin so far, but they are likely to arrive at some point, as they have been confirmed in Michigan.

HWA (Adelges tsugae) is an invasive, sucking insect pest of hemlock trees. The white, cottony egg sacs of HWA can be seen on the undersides of hemlock branches at the base of needles year-round. HWA saliva enters the tree while feeding. The saliva is toxic and causes needle drop and twig dieback, progressing to tree mortality in 4-10 years.

Continue reading “Check Conifers For Invasive Adelgids” →

Heterobasidion Root Disease Found In Door County

Posted on by akabelowsky
Two photos of the same spot on a tree in Door County, showing Heterobasidion root disease fruiting bodies (left) and the basal wound beneath them (right).

Two photos of the same spot on a tree in Door County, showing Heterobasidion root disease fruiting bodies (left) and the basal wound beneath them (right). / Photo Credits: Bill McNee, Wisconsin DNR

By Bill McNee, DNR Forest Health Specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942

Heterobasidion root disease (HRD), formerly known as annosum root rot, was recently found in Door County for the first time.

In mid-September, several suspected HRD fruiting bodies were spotted in a white spruce plantation on privately owned land in the town of Sevastopol. One cluster of fruiting bodies located at the base of a dead spruce was confirmed as Heterobasidion irregulare, the fungal pathogen that causes HRD. The other fruiting bodies were identified as a native decay fungus that has a similar appearance.

Continue reading “Heterobasidion Root Disease Found In Door County” →

Winter Squirrel Damage Killing Maple Branches

Posted on by akabelowsky

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

Two photos show maple branches that died recently due to previous damage from squirrels.

Two photos show maple branches that died recently due to previous damage from squirrels. / Photo Credit: Linda Williams, Wisconsin DNR

Have you noticed maple branches suddenly dying this summer?

Sudden mortality of maple branches during the summer in northern Wisconsin is often a result of squirrel damage that occurred in late winter and early spring.

In late winter and early spring, gray squirrels strip the bark of maples to get at the sweet maple sap. When the damage is extensive or severe, entire trees or branches will be killed immediately and will not leaf out in the spring.

Continue reading “Winter Squirrel Damage Killing Maple Branches” →

Jack Pine Budworm Outbreak Subsides

Posted on by akabelowsky

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

Aerial view of jack pine budworm defoliation in jack pine stands in Douglas County during the 2023 outbreak. / Photo Credit: Paul Cigan, Wisconsin DNR

Jack pine defoliation caused by the jack pine budworm (JPBW) continued at mostly light levels this year, affecting stands in the Central and Northwest Sands Ecological Regions of Wisconsin.

In the Northwest Sands, jack pine stands experienced light and scattered defoliation across Burnett, Douglas, Polk and Washburn counties. In the Central Sands, JPBW caused moderate to heavy defoliation across roughly 500 acres of jack pine on county and state forests in Jackson County, east of Black River Falls.

Continue reading “Jack Pine Budworm Outbreak Subsides” →

Hemlock Monitored After 2023 Defoliation

Posted on by akabelowsky

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

Photo showing that hemlock crowns remained thin this summer at a Vilas County plot that saw defoliation by spruce budworm in 2023.

Hemlock crowns remained thin this summer at a Vilas County plot that saw defoliation by spruce budworm in 2023. / Photo Credit: Linda Williams, Wisconsin DNR

Spruce budworm was observed defoliating a stand of hemlock trees in Vilas County in 2023. This stand was revisited in 2024 and although defoliation was only light this year, significant thinning in the tops of hemlocks was noted.

Hemlock is not a preferred host for spruce budworm, and the defoliation in 2023 was due to an extremely high population of spruce budworm in that area.

Continue reading “Hemlock Monitored After 2023 Defoliation” →

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” →

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” →