Month: April 2023

Aerial Spraying Set For Four State Sites

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By Bill McNee, 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

At a suitable time between early May and early June, an airplane will spray parts of four DNR properties to reduce the population of spongy moth caterpillars (formerly known as gypsy moth). Treatment dates will depend on weather conditions and caterpillar development.

This year’s high populations threaten to strip trees of their leaves and possibly kill high-value trees at these properties.

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Heterobasidion Root Disease Approaches

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By Alex Feltmeyer, Forest Health Specialist, Plover, Alexandra.Feltmeyer@wisconsin.gov or 715-340-3810

A Heterobasidian root disease fruiting body at the base of a white pine sapling

A Heterobasidion root disease fruiting body is found at the base of a white pine sapling in the understory. Photo: Wisconsin DNR Forest Health

Heterobasidion Root Disease (formerly annosum root rot or Fomes root rot) is a serious disease of conifers that causes reduced height, shoot and diameter growth along with thin and yellowish/red foliage, ultimately causing mortality.

The disease becomes established in a new stand when spores of the fungus land on freshly cut stumps made by any forest management that creates cut stumps. After the disease becomes established, it spreads underground through root systems into adjacent trees. In this way, we often find pockets or groups of trees in various stages of decline.

Movement through the root systems contributes to significant spread throughout stands of conifers, impacting the regeneration of conifers within these pockets.

Mortality usually starts occurring three to eight years after a thinning operation. During this time, perennial fruiting bodies of the fungus begin to develop around the base of cut stumps or dead trees.

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Hungry Squirrels Find Trees Tasty

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

Maple branches with light colored areas where squirrels removed bark.

Squirrels remove the bark of maples, leaving bright bare spots. Photo: Wisconsin DNR

It’s the time of year when we start to see scattered maple trees stripped of their bark. Squirrels cause this damage — which can be limited to a few small areas the size of a tennis ball or can extend to cover many feet of branches or the main stem.

The squirrels are going after the cambium layer, just under the bark, that tastes slightly sweet from the sap. Smooth bark is easier for squirrels to chew, so young trees or branches with thin bark are likelier to be stripped than those with older, furrowed bark.

At this time of year, the pale wood of the branches that have had the bark stripped off is nearly white; later in the season, this wood will darken or even turn black with sooty mold. This type of feeding can remove enough bark to girdle the branches or the main stem, causing the tree to die from that point to the end of the branch.

Branches that are not completely girdled will continue to grow, and callus tissue will begin to grow over the wounds. If branches are nearly girdled, they may leaf out this spring and then suddenly wilt and die as hot weather hits because the tree can’t deliver enough water to keep those leaves alive. Continue reading “Hungry Squirrels Find Trees Tasty” →

Lab Assistant Departs

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By Art Kabelowsky, DNR Forest Health Outreach Specialist, Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

Another photo will be hung on the unofficial “Wall of Fame” bulletin board inside the Department of Natural Resources Forest Health Lab in Fitchburg.

Ethan Wachendorf, who joined DNR as a laboratory assistant on May 23, 2022, departed on Thursday, March 23, to pursue a Master of Science in plant pathology at Michigan State University in East Lansing.

Outgoing Forest Health lab assistant Ethan Wachendorf at a microscope

Ethan Wachendorf

Wachendorf started as a summer lab assistant, but at the start of 2023 became a dual LTE, working as the lab assistant. The Colorado native joined the DNR after earning a bachelor’s degree in government (with a minor in biology) from Lawrence University in Appleton.

Wachendorf said he was drawn to Michigan State for post-graduate studies after working with Dr. Monique Sakalidis, who runs the university’s forest pathology lab.

“I’ll be working on oak wilt testing and management techniques, such as herbicide, fungicide, rapid response and the way the trees change physiologically,” Wachendorf said.

He will work full-time at the Michigan State lab until the fall semester, when he will split his time between lab duties and classwork.
His Wisconsin impressions include how “Midwest nice” the people are, how good the beer is, and how cold it gets — and stays — in the Badger state.