Forest Health News

Garlic Mustard Aphid Advances

Posted on by akabelowsky

Art Kabelowsky, DNR Forest Health outreach and communications specialist
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Photo of garlic mustard aphids on a leaf.

Dozens of garlic mustard aphids feed on the underside of a garlic mustard leaf in Michigan. The small, dark aphids, originally from Europe, have been found in Wisconsin and other states after first being discovered in Ohio in 2021. Photo: Rebecah Troutman, Holden Forests and Gardens, Kirtland, Ohio.

A new tool in the effort to fight invasive garlic mustard appears ready to make its move in Wisconsin.

The garlic mustard aphid, Lipaphis alliariae, has been moving westward after being discovered in Ohio in 2021. Since then, isolated populations have also been found in Wisconsin, Connecticut, Massachusetts, Michigan and Minnesota.

Continue reading “Garlic Mustard Aphid Advances” →

Spongy Moth Forecast Caution Issued

Posted on by akabelowsky

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

Photo of mature spongy moth caterpillar

Mature spongy moth caterpillar on a leaf. Photo: Bill McNee, Wisconsin DNR

Wisconsin Department of Natural Resources Forest Health staff are cautioning Wisconsin residents that the next two months could bring the worst spongy moth outbreak in more than a decade.

The caterpillars of this invasive insect prefer to feed on oak, birch, crabapple, aspen and willow leaves, but will also feed on many other tree and shrub species.

Southern Wisconsin and parts of the north are already in a high-population outbreak that is predicted to continue and spread. Populations have remained high due to a low incidence of caterpillar-killing diseases last summer. In addition, weather conditions in 2023 are favorable for the caterpillars and unfavorable for Entomophaga maimaiga, a fungus that kills spongy moth caterpillars.

Property owners are encouraged to examine their trees and take action.  Specifically:

Continue reading “Spongy Moth Forecast Caution Issued” →

Douglas County Joins Spongy Moth Quarantine

Posted on by akabelowsky
A spongy moth larva eats a leaf.

A spongy moth larva eats a leaf.

By Paul Cigan, DNR plant pest and disease specialist
Paul.Cigan@wisconsin.gov or 715-416-4920

In early April, Douglas County became the 53rd Wisconsin county added to the state’s spongy moth quarantine list after a discovery that the invasive insect (formerly known as gypsy moth) had become established in the county.

The United States Department of Agriculture-Animal and Plant Health Inspection Service (USDA-APHIS) and the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) made the determination based on results of a monitoring program of adult moths and other life stages.

Continue reading “Douglas County Joins Spongy Moth Quarantine” →

Aerial Spraying Coming To Four State Properties

Posted on by akabelowsky

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

Spray aircraft used in spongy moth control

Spray aircraft used in spongy moth control. Photo: Bill McNee, Wisconsin DNR

The Wisconsin Department of Natural Resources (DNR) is taking action in the coming weeks in its battle against spongy moth (formerly known as gypsy moth) caterpillars.

An airplane will spray parts of four DNR properties to reduce the population of the hungry pest.

This year, high numbers of spongy moths threaten to strip trees of their leaves and may even kill high-value trees at these properties.

Continue reading “Aerial Spraying Coming To Four State Properties” →

Prepare — Spongy Moth Caterpillars To Return

Posted on by akabelowsky

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

Spongy moth caterpillars clustered below a sticky barrier.

Spongy moth caterpillars clustered below a sticky barrier. Photo: Mark Guthmiller, Wisconsin DNR

This June and July, spongy moth populations are predicted to reach damaging levels in parts of Wisconsin. Populations began to rise in 2020, and this is likely to be the third year of the pest outbreak in some regions of southern Wisconsin.

At present, damaging populations are expected to be most noticeable in southern counties, counties to the north of the city of Green Bay, and in far northern Wisconsin near Lake Superior. Additional areas are likely to have high populations that are more concentrated in size.

Continue reading “Prepare — Spongy Moth Caterpillars To Return” →

Emerald Ash Borer Found In Vilas County

Posted on by akabelowsky
Adult emerald ash borer beetle.

Adult emerald ash borer beetle. Photo: Wisconsin DNR.

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

Vilas County has the dubious distinction of becoming the first new Wisconsin county in 2023 to have a discovery of emerald ash borer (EAB).

EAB continues to spread into areas of northern Wisconsin. The first Vilas County detection was in the town of Lincoln. Additional infested trees have since been found in the town of Cloverland and the city of Eagle River. Continue reading “Emerald Ash Borer Found In Vilas County” →

Effects Of Winter Take Toll On Trees

Posted on by akabelowsky
A group of planted white pine saplings with varying amounts of brown needles caused by winter desiccation.

Minor to moderate damage to white pine needles caused by winter desiccation. Photo: Wisconsin DNR

 

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg

michael.hillstrom@wisconsin.gov

Winter damage is one of the most commonly reported tree issues in early spring. The damage may be minor, such as off-color needles that are quickly replaced, but could be as severe as partial- or whole-tree mortality.

Winter desiccation occurs when conifers begin photosynthesizing on warm, windy days in late winter or early spring. Conifers may dry out in these conditions if they use their stored water and cannot replace it because the ground is still frozen.

Continue reading “Effects Of Winter Take Toll On Trees” →

USDA Seeks Donations Of Infested Ash Trees

Posted on by akabelowsky

By Kyle Loughlin, Field Team Lead, USDA-APHIS
kyle.m.loughlin@usda.govor 734-732-0025

A window cut into a tree’s bark shows signs of emerald ash borer infestation.

USDA staff cut a ‘bark window’ in green ash to uncover signs of emerald ash borer. Photo: US Department of Agriculture

The U.S. Department of Agriculture (USDA) is asking Wisconsin landowners for help in the battle against emerald ash borer (EAB).

EAB is an invasive insect from Asia that was first introduced into the United States in 2002. Since its discovery, EAB has caused the death and decline of tens of millions of ash trees.

The USDA is asking Wisconsin landowners to donate live ash trees infested with EAB to support USDA’s biological control program. The staff will use the wood to rear EAB’s natural enemies, which will then be released in Wisconsin and 31 other EAB-infested states and Washington, D.C.

Continue reading “USDA Seeks Donations Of Infested Ash Trees” →

Oak Harvesting During A Cold Spring

Posted on by akabelowsky

By Kyoko Scanlon, DNR Forest Pathologist, Kyoko.Scanlon@wisconsin.gov or 608-235-7532

Oak trees in a snow-covered field

The colder weather in spring 2023 might delay the DNR’s recommendations to avoid trimming or cutting from April through July. Photo: Wisconsin DNR

It’s April, but in much of Wisconsin the weather doesn’t seem to have gotten the message.

You may be wondering if the oak harvesting restriction that started on April 1 (south of the tension zone) and will start on April 15 (north of the tension zone) might be pushed back due to unusually cold temperatures.

Even with unusually cold springs, we remain consistent with the same general messages: “Stop pruning in April” and “Avoid harvesting in April (south of the tension zone).” We do this for the following reasons:

  • It is difficult to spread the word in a timely manner about when to begin the restrictions. Often when spring comes late, it arrives suddenly; in those cases, before we know it, we’ve entered the high-risk period.
  • We want to be consistent in stressing the messages of the existing oak harvesting guidelines, so that the public is aware of them.

Continue reading “Oak Harvesting During A Cold Spring” →

Protect Oaks During Spring Clean-up

Posted on by akabelowsky

By Paul Cigan, DNR plant pest and disease specialist, Paul.Cigan@wisconsin.gov or 715-416-4920

An oak tree with branches trimmed

To prevent the spread of often-fatal oak wilt disease, do not prune, cut or wound oaks from April through July. Photo: Wisconsin DNR

With the arrival of spring, the Wisconsin Department of Natural Resources (DNR) recommends protecting oaks from the often-fatal oak wilt disease by refraining from pruning, cutting or injuring oak trees from April through July.

The highest risk period for oak wilt introduction to a new site is in spring and early summer. Pruning and cutting oaks exposes living tree tissue beneath the bark to potential infection. The disease rapidly kills trees in the red oak group and weakens those in the white oak group.

Sap-feeding beetles spread the disease between oaks by carrying oak wilt spores from infected trees or firewood to fresh, exposed tree wounds. Healthy oaks and freshly cut oak stumps can become infected as quickly as 15 minutes after a wound is made from a pruning cut or broken branch.

Continue reading “Protect Oaks During Spring Clean-up” →