Disease

Resources to Help Urban Foresters Set And Meet Tree Diversity Goals

Posted on by janness

By Shahla Werner, Urban Forestry Council Member and Department of Agriculture, Trade and Consumer Protection Plant Protection Section Manager

Urban foresters are increasingly aware of the importance of tree species, age and size diversity to ensure resilient tree canopy and all the associated benefits in their communities. The 20-10-5 rule, which specifies that no more than 20% of trees planted should be from one family, no more than 10% from one genus and no more than 5% from one species (including cultivars), can be helpful in setting tree diversity goals. Applying these guidelines can provide urban forests some protection against huge losses caused by invasive forest pests. Continue reading “Resources to Help Urban Foresters Set And Meet Tree Diversity Goals” →

Watch For Oak Decline And Mortality This Summer

Posted on by akabelowsky
Oak decline and mortality at Big Foot Beach State Park in 2024.

Oak decline and mortality at Big Foot Beach State Park in 2024. / Photo Credit: Wisconsin DNR

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

Oak decline and mortality continue to be an issue in Wisconsin, and because of the recent droughts and spongy moth outbreak, we expect these impacts to become more widespread this summer.

Forest decline is the progressive loss of tree and stand vigor and health over several years without obvious evidence of a single causal factor. Typically, trees die in a scattered fashion across a large area over several years. The additional stress from defoliation can result in pockets of heavy oak mortality, particularly on dry, sandy sites and steep, rocky ridges and hills.

Continue reading “Watch For Oak Decline And Mortality This Summer” →

Spring Brings Opportunities To Protect Oak Trees

Posted on by akabelowsky
A photo of an oak tree with a branch that has been pruned, but not treated with protective paint to prevent infection with oak wilt.

Pruning, cutting, or wounding oaks during April through July leaves them vulnerable to oak wilt. / Photo Credit: Paul Cigan, Wisconsin DNR

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

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

Oak wilt is a serious disease that kills trees in the red oak group (including pin oak, northern red oak and black oak) and weakens those in the white oak group (bur oak, swamp white oak, white oak and English oak).

Continue reading “Spring Brings Opportunities To Protect Oak Trees” →

Heterobasidion Root Disease Online Maps Updated

Posted on by akabelowsky
Photo of a tree showing fruiting bodies of Heterobasidion root disease at its trunk.

A tree shows fruiting bodies of Heterobasidion root disease at its trunk. / Photo Credit: Wisconsin DNR

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

Heterobasidion root disease (HRD), a destructive fungal disease, continues to be found in Wisconsin.

The Wisconsin Department of Natural Resources (DNR) has confirmed detections in several stands over recent months.

The DNR’s 6-mile and 25-mile buffer zone maps have been updated based on the locations of the newly confirmed stands. The most notable changes due to expanded buffer zones have taken place in Door, Marinette, Milwaukee and Pierce counties.

Continue reading “Heterobasidion Root Disease Online Maps Updated” →

A Wonderful Winter Display: Phomopsis Galls

Posted on by akabelowsky
Phomopsis galls are plentiful on branches of a 120-year-old red oak tree in Clark County, Wisconsin, in 2024.

Phomopsis galls are plentiful on branches of a 120-year-old red oak tree in Clark County, Wisconsin, in 2024. / Photo Credit: Kris Wimme, retired Wisconsin DNR forester

By Alex Hornung, DNR Forest Health Specialist, Plover
Alexandra.Hornung@wisconsin.gov

It is the perfect time of year to be on the lookout for galls – woody growths or swellings on tree branches that are typically oblong in shape and of varying sizes.

They can often be found on small branches, but occasionally they can affect large branches or even the main stem. Galls can occur for several reasons, ranging from fungi to bacteria to insect activity.

One type, Phomopsis gall, can be particularly impressive to see. Galls formed due to this native fungus mostly occur on oak, hickory and maple trees in Wisconsin.

 

Continue reading “A Wonderful Winter Display: Phomopsis Galls” →

It’s A Good Time To Work On Oak Trees

Posted on by akabelowsky
A person prunes a tree during the winter months.

Winter is an ideal time to perform pruning and trimming work on oak leaves. / Photo Credit: Wisconsin DNR

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

Winter is an ideal time to perform trimming, cutting and brush removal work on and near oak trees.

For one thing, it’s a low-risk period for the trees to be infected with oak wilt, a fungal disease spread by beetles. When a red oak is infected with oak wilt, it will die that year; the disease also stresses trees in the white oak group, often fatal with bur oaks and swamp white oaks.

Continue reading “It’s A Good Time To Work On Oak Trees” →

Tree Disease Maps Have Migrated

Posted on by akabelowsky
The Wisconsin web map for Heterobasidion root disease, available through ArcGIS Online.

The Wisconsin web map for Heterobasidion root disease, available through ArcGIS Online. / Map Credit: Paul Cigan, Wisconsin DNR

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

The Wisconsin Department of Natural Resources (DNR) Forest Health program hosts two interactive web maps on its webpage:

Heterobasidion Root Disease

Oak Wilt Seasonal Harvesting Opportunities

Continue reading “Tree Disease Maps Have Migrated” →

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” →

Oak Decline Continues In Southern Wisconsin

Posted on by akabelowsky

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

Oak decline at Big Foot Beach State Park caused by flooding, drought, spongy moth defoliation, twolined chestnut borer and Armillaria. / Photo Credit: Michael Hillstrom, Wisconsin DNR

Bur and white oaks, most of them more than 100 years old, have experienced rapid mortality (within one to two years) over the past four years in southern Wisconsin and neighboring states. Research into the cause is ongoing, but the evidence so far suggests it’s an oak decline.

Oak declines are not caused by a single issue, but rather by the stacking of multiple health issues. Drought, flooding, storm damage, age, twolined chestnut borer, Armillaria and other root pathogens, and spongy moth and oak leafroller defoliation all play a role in the damage.

Continue reading “Oak Decline Continues In Southern Wisconsin” →