Statewide Forest Health

DNR Staff Gets Tree Injection Training

Photo of a tree marked with a ribbon for pesticide/fungicide injection.
Photo of a worker demonstrating a tree injection nozzle.

Cory McCurry, an arborologist with Rainbow Ecoscience, talks with DNR Parks and Forest Health employees while demonstrating the use of a nozzle component of the Q-Connect tree injection system currently in use at state properties. Photo: Wisconsin DNR.

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

LAKE GENEVA, Wisconsin — Fifteen employees of the Wisconsin Department of Natural Resources gathered at Big Foot Beach State Park on May 16 to learn more about using injections of systemic pesticides to protect the health of high-value trees at state properties.

Ten Wisconsin State Parks employees and five members of the DNR’s Forest Health team met with representatives of Rainbow Ecoscience and Bartlett Tree Experts to witness a demonstration of best practices for tree injections.

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Garlic Mustard Aphid Advances

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.

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Douglas County Joins Spongy Moth Quarantine

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.

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Prepare — Spongy Moth Caterpillars To Return

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.

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Effects Of Winter Take Toll On Trees

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.

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USDA Seeks Donations Of Infested Ash Trees

By Kyle Loughlin, Field Team Lead, USDA-APHIS
kyle.m.loughlin@usda.gov
or 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.

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Oak Harvesting During A Cold Spring

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.

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Make Plans To Control Spongy Moth Before The Eggs Hatch

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

Spongy moth (formerly known as gypsy moth) egg masses typically begin to hatch in April as temperatures warm. Each mass that hatches may produce up to 1,000 leaf-eating caterpillars.

Now is a great time to inspect your trees for egg masses and treat or remove any masses within reach. Wisconsin weather has been favorable for this pest over the last three years and populations have grown.

Photo of three spongy moth egg masses on the underside of a pine branch in Walworth County.

Three spongy moth egg masses on the underside of a pine branch in Walworth County. Photo: Bill McNee, Wisconsin DNR.

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Treat Your Valuable Ash Trees Against Emerald Ash Borer This Spring

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

Property owners with healthy, valuable ash trees are encouraged to treat them with insecticide this spring to protect against emerald ash borer (EAB). The pest is currently the most damaging threat to trees in Wisconsin, killing more than 99% of the ash trees it infests.

Woodpecker damage during the winter is often the first sign that an ash tree is infested. The birds remove pieces of bark while feeding on EAB larvae inside the tree. Insecticide treatment of infested ash trees is more likely to be successful if the trees have low or moderate levels of woodpecker damage.

Now is a good time to consider insecticide protection, because the treatments are typically done between mid-April and mid-May. Ash (in the genus Fraxinus) is the only type of tree that needs protection against EAB. Mountain ash and prickly ash do not need protection because the insect does not attack them.

Ash tree branch in West Allis has been damaged by woodpeckers. Sections of bark are missing, exposing the tree’s light brown wood.

This ash tree branch in West Allis has been damaged by woodpeckers feeding on EAB larvae beneath the bark.
Photo: Bill McNee, Wisconsin DNR.

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Fighting Invasive Plants

Invasive plants are a major threat to Wisconsin’s forests, highlighted in the forest health chapter of Wisconsin’s Forest Action Plan. Invasive plants limit tree regeneration, reduce plant diversity and increase management costs. Recent Forest Inventory and Analysis data from the USDA Forest Service found that more than half of forest sites surveyed in Wisconsin had two or more invasive plant species. Forest landowners should learn to recognize common invasive plants like buckthorns, honeysuckles and garlic mustard. Mobile applications are a handy tool for landowners to learn to identify the plant species in their woods (e.g., PlantNet, iNaturalist) and report invasives (e.g., EDDMapS). For information about the regulated invasive plants in Wisconsin visit the Wisconsin Department of Natural Resources’ (DNR) Terrestrial Invasive Species page.

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