Central WI Forest Health

Tree mortality continues in flooded forests

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

Wisconsin has had historically wet weather the last five years, and the impacts to trees are escalating. Forest health staff have noted significant mortality of trees along lakes and rivers from rising water levels. Trees growing in low areas that have not flooded in many years are also being impacted.

Photo of flooded lakeside forest and dead trees around margin of lake.

Rising lake water levels causing conifer mortality.

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Summary of spring 2020 balsam fir mortality event

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

The sudden balsam fir mortality event in Wisconsin in 2020 was similar to the spring 2018 mortality event, although the mortality this year was more scattered, and fewer trees were killed.

A balsam fir tree with a dead crown that has retained its needles.

Trees that died suddenly this spring retained their needles, which turned reddish-brown to brown.

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New emerald ash borer county detections: an update from DATCP and DNR

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), in partnership with the Wisconsin DNR, has detected emerald ash borer in four new counties (Dunn, Oconto, Pepin and Shawano). Please read this DATCP article for more information.

Adult emerald ash borer beetle.

Adult emerald ash borer beetle.

If you are a landowner and have questions about ash trees in your woodlot, contact your local DNR forester using the Forestry Assistance Locator.  

Gypsy moth populations rebound in 2020 – look for egg masses this fall

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

The summer of 2020 saw a major rebound of the gypsy moth population after several years of weather conditions that were unfavorable for the non-native, defoliating pest. A mild winter and average summer temperatures/precipitation during the caterpillar stage were all favorable for a population increase.

Gypsy moth egg masses are tan-colored lumps about the size of a nickel or quarter.

Female moth laying eggs on tree trunk.

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Oak webworms, blotchminers, skeletonizers and dead branch tips in late summer

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

If you’ve ever looked closely at oak leaves in late summer you know that you can find lots of interesting things on them this time of year. You’ll see anything from a variety of caterpillars and galls of all shapes and sizes to dead portions of branches caused by insects and diseases. These late season defoliators rarely cause actual health issues for the tree, and rarely require any control, but they can be very noticeable with some dramatic damage. Continue reading “Oak webworms, blotchminers, skeletonizers and dead branch tips in late summer”

Spruce budworm and balsam fir mortality in northern Wisconsin

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

Spruce budworm defoliation was severe in many areas of northern Wisconsin this year. New needles on balsam fir and spruce were eaten, although in most areas the balsam fir had greater amounts of defoliation than the spruce. Feeding by this native caterpillar for several years in a row can cause trees to start to decline and even die, which is occurring in a number of areas of northern Wisconsin.

Mortality of balsam fir due to repeated defoliation by spruce budworm. Green trees in this photo, including hardwoods and pines, are not fed upon by spruce budworm.

Mortality of balsam fir due to repeated defoliation by spruce budworm. Green trees in this photo, including hardwoods and pines, are not fed upon by spruce budworm.

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Wondering about large yellow wasps?

If you’ve noticed large yellow wasps flying around this summer, you may be wondering whether you’ve seen the Asian giant hornet (aka “murder hornet”). This probably gave you some pause considering all the headlines they received earlier this year,  but fortunately for Wisconsin and much of the Midwest, murder hornets have not yet been found in the region.

Close-up photo of cicada killer.

The cicada killer is a common native insect in the Midwest.

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Be on the lookout for beech leaf disease

By Elly Voigt, forest health lab assistant, Fitchburg

Beech leaf disease (BLD) is a relatively recently discovered, destructive disease of beech trees in the US. It was first observed in 2012 in Ohio and has since spread to areas of Pennsylvania, New York, Connecticut, Rhode Island, Massachusetts and Ontario, Canada. BLD affects our native beech species, American beech (Fagus grandifolia) and ornamental beech species, including European beech (Fagus sylvatica). The disease has not yet been observed in Wisconsin but could become an issue in the future.

Overhead view of beech leaves show puckering of leaf segments.

Symptomatic leaf puckering of a beech tree with BLD. Credit: Ohio State University.

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Interactive HRD stump treatment guidelines available online

The HRD stump treatment guidelines are now available in an interactive format to make it easier to obtain stand-specific recommendations. You can find the link called “Interactive guidelines” on the right side bar under “Additional Resources” at the DNR HRD webpage. The user will be asked a series of questions and then a stand-specific recommendation will be provided at the end. The interactive guidelines incorporate Exceptions and Modifications described in the guidelines. Check it out!        

Reports of sudden balsam fir mortality

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

In early June we started getting reports of balsam fir trees rapidly changing from green to rusty red and dying in just a matter of weeks. Reports and observations are still coming in at the time of this writing, so this article gives a brief synopsis of what we’ve seen so far this year. Symptoms have been observed in some northern and central counties.

The top half of a balsam fir died rapidly this spring due to reasons we are still exploring.

Some balsam fir crowns died rapidly this spring for reasons still being explored.

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