Larch casebearer and eastern larch beetle: two problems for tamarack

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665 

Tamarack trees are sending out their needles this spring, and larch casebearer caterpillars are feeding on them. In northern Wisconsin, where the trees didn’t push needles out until the end of May, the caterpillars were impatiently waiting to begin feeding and in some counties the damage is now severe. Larch casebearers defoliate tamarack trees early in the season, causing them to look pale green or straw yellow or even brown in cases of severe defoliation.

A horizon of tamarack trees defoliated by larch casebearer appear straw-colored or tan from a distance.

Tamarack trees defoliated by larch casebearer will appear straw-colored or tan from a distance. Photo taken May 28 in Oneida County.

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All about earthworms: nightcrawler edition

By Bernie Williams, invasive plants and earthworms specialist, Madison, Bernadette.Williams@wisconsin.gov, 608-444-6948

As the weather warms up and more of us are out in our gardens digging around, it seems like a good time to learn a few things about those fascinating and beautiful worms you keep encountering. Keep reading for the first installment in a series about invasive worms.

Close-up of nightcrawler shows its reddish-pink body in detail.

Nightcrawlers have reddish-pink bodies and can be -8 inches long when mature.

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What’s that orange goo?!

By Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

What’s the orange goo on that tree?!

Should I fight or should I flee?

I bet forest health staff can ID!

Close-up of orange gelatinous gall growing on cedar caused by cedar apple rust.

The spore-producing, slimy, orange gall caused by cedar apple rust fungus.

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Spruce budworm defoliation showing up

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

Spruce budworm defoliation is becoming noticeable in northern and central Wisconsin counties as clipped host tree foliage stuck in the caterpillars’ webbing turns rusty red. The caterpillars should pupate soon, and moths will emerge a couple weeks later to mate and lay eggs. Spruce budworm is a native insect with periodic outbreaks that defoliates spruce and balsam fir in the Midwest.

Close-up of spruce budworm caterpillar near the silk web it spins around branch tips.

Spruce budworm caterpillar near the silk webbing it spins on branch tips.

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Pine tortoise scale can cause branch and tree mortality, sooty mold problems

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

Pine tortoise scales are sometimes found at very heavy densities on jack and scotch pine twigs. In Wisconsin they prefer young jack pine trees, inserting their straw-like mouthparts into twigs and sucking out the sap. When populations are high, pine tortoise scale can cause branch mortality and even whole tree decline.

Tiny pine tortoise scales clustered on a pine branch tip.

Pine tortoise scales are so plentiful on this twig that they are practically on top of one another.

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Wisconsin DNR’s Forest Health Program: 71 years of getting the bugs out

By Andrea Diss Torrance, invasive insects program coordinator, andrea.disstorrance@wisconsin.gov, 608-516-2223 and Bill McNee, forest health specialist, Oshkosh, Bill.Mcnee@wisconsin.gov, 920-360-0942

Wisconsin has a long history of forestry management, with a state program beginning in 1904 that later expanded in 1949 to include the survey and management of forest pests. The first state forest entomologist, Norbert Underwood, was hired that year. Nearly ten years later, Mr. Underwood was joined by a forest health program coordinator and three additional forest entomologists. The entomologists were based in Spooner, Antigo, Oshkosh and Black River Falls, while the coordinator, and later a pathologist, were stationed at the forest health lab in Fitchburg.

First state forest entomologist, Norbert Underwood, was hired in 1949.

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Forest health staff fight forest pests

By Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

Wisconsin forests are impacted by a large variety of native and non-native insects, diseases, plants and worms. Extreme weather events like last year’s widespread blowdown incident also have significant impacts to the health of Wisconsin’s forests. The role of a forest health specialist is to assess forest damage caused by biotic and abiotic agents and provide management recommendations to return the forest to full function.

Forest health specialists discussing symptomatic red pine trees while on a site visit.

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The evolving landscape of invasive species and their control options in Wisconsin

By Andrea Diss Torrance, invasive insects program coordinator, andrea.disstorrance@wisconsin.gov, 608-516-2223

Many people know that invasive species are a concern in Wisconsin’s natural communities both on land and in water. But fewer people are aware that invasive species are not a new threat and that over time, we have developed strategies to reduce their spread and limit their damage to a tolerable level.

As soon as people from other continents started arriving in Wisconsin, so did the non-native plants, insects and microorganisms that came with them. Most of these non-native species are either beneficial or cause no harm, including well-known examples like honeybees, daffodils and even the bacteria used in cheese production. In contrast, the non-native species that damage native and domestic plants are known as invasive species, and over the years people have developed policies and practices to limit their impacts to native plant communities.

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Impacts and management of the invasive emerald ash borer

By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

Emerald ash borer (EAB) was first identified in Wisconsin in 2008, although it was likely present in the state for a few years prior to detection. Since EAB doesn’t travel far on its own, some experts think it was unknowingly brought into the state on infested firewood, which is a common introduction pathway for many insects and diseases. The Wisconsin DNR Firewood page has more info on firewood and the insects and diseases that can travel on it.

Since its arrival in Wisconsin, EAB has steadily killed ash trees wherever it has been found. As of the writing of this article, there has been much more ash tree mortality in the southern half of Wisconsin than the northern half of the state where known EAB infestations are still widely scattered.

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Blue ash: Wisconsin’s little-known ash tree

By Bill McNee, forest health specialist, Oshkosh, Bill.Mcnee@wisconsin.gov, 920-360-0942

Many people interested in trees know about Wisconsin’s white, green and black ash species. However, there’s a fourth species that fewer people know about. Blue ash, Fraxinus quadrangulata, occurs naturally only at a few sites in Waukesha County. It can easily be identified by the cork ridges on the twigs, which give them a four-sided, square appearance. The tree was given its name because of the blue dye that is produced by soaking the inner bark in water.

Four-sided, square twig of a blue ash. Photo by Bill McNee.

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