weather

Hail Damage Can Cause Dieback, Whole-Tree Mortality

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Photo of a young aspen showing signs of severe impact from hail. Arrows indicate each point of impact.

A young aspen shows signs of severe impact from hail. Arrows indicate each point of impact. / Photo Credit: Wisconsin DNR

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

Several high-impact storms across the state this summer have pummeled trees with hail. The photos accompanying this article show the kind of damage hail can bring to forests.

The initial damage following a significant hailstorm can immediately appear severe. But give it a month or two, and the damage can look even more pronounced.

Pines in particular will start to turn varying levels of brown, depending on the amount of damage they sustained. Damage to the branches and twigs is not limited to just the spot where the hail hit. As the summer goes on, damaged areas of bark that were cracked by the hail impact will often split open further and allow more drying and additional separation of the bark from the wood, which kills that area of the branch.

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Frost’s Bite: How Do Insects Survive Winter?

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An emerald ash borer larva overwinters by curling into a J shape inside a channel in an ash tree in Brookfield in 2019.

An emerald ash borer larva overwinters by curling into a J shape inside a channel in an ash tree in Brookfield in 2019. / Photo Credit: Bill McNee, Wisconsin DNR

By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg

Michael.Hillstrom@wisconsin.gov

As winter’s chill persists, Wisconsin Department of Natural Resources (DNR) Forest Health staff members are often asked how cold it needs to get to kill insects, especially invasives.

The answer varies from species to species, but many insects are well adapted to dealing with freezing winter temperatures. Some, such as monarchs, avoid the issue and migrate south for the winter. Others, such as multicolored Asian ladybeetles, annoy us with their presence in our homes and offices as they try to avoid the cold until spring.

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Five Years Later, Effects Of Derecho Remain

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

Over the night of July 19-20, 2019, Mother Nature carved a massive swath of destruction through northern Wisconsin.

Today, after years of hard work cleaning up after the massive derecho windstorm of ’19, local foresters, work crews and landowners have only begun to understand the breadth and depth of the damage as they process the lessons learned.

In many areas, the recovery work remains incomplete. Some of that forest damage will never receive direct attention.

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Weather Whiplash Affects Pine Stands

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Swath of dead pine due to high water table mortality

A swath of pine dead due to high water table mortality in 2020 in northeast Wisconsin.

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

Many pine stands across central and northeast Wisconsin are being impacted by the change from high levels of precipitation to extreme drought that has occurred over the last 5-7 years.

Drastic or sudden changes can be particularly stressful to trees of all species, but especially to pine stands that prefer well-drained soil types.

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