Forest Health News

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

Posted on by margueriterapp

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

Posted on by margueriterapp

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” →

Green-striped mapleworm in northern Wisconsin

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

Green-striped mapleworm caterpillars feed gregariously, so where you see one, you’re bound to see more. Their preferred hosts are red and sugar maple, but they can feed on oak and beech as well, especially if those species are mixed in with maples. As they feed, they leave behind only the main veins of the leaves. The adult moth is the lovely rosy maple moth.

Green-striped mapleworm caterpillar clinging to the underside of a maple leaf.

Green-striped mapleworm caterpillar.

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Spruce budworm and balsam fir mortality in northern Wisconsin

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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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Redheaded pine sawfly reported in northern Wisconsin

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

For the second year in a row, colonies of redheaded pine sawfly have been reported on understory red pine in northern Wisconsin, with the most reports coming from Vilas County. Redheaded pine sawfly was also noted in Portage County in central Wisconsin this year.

Redheaded pine sawfly larvae feed as a group, as shown in this photo where many sawflies are clustered on a single twig.

Redheaded pine sawfly larvae feed as a group.

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Jack pine budworm defoliation seen in Juneau County

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By Todd Lanigan, forest health specialist, Eau Claire, todd.lanigan@wisconsin.gov, 715-210-0150

Jack pine budworm, a native defoliator of jack pine and other conifers, caused defoliation of jack pine in the Town of Clearfield, Juneau County. Defoliation levels ranged from light to moderate, with some areas along roadways having higher levels of defoliation.

Jack pine trees defoliated by jack pine budworm.

Jack pine trees defoliated by jack pine budworm.

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Wondering about large yellow wasps?

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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

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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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Revised aerial spray guide now available

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

Increasing reports of gypsy moth, forest tent caterpillar and other defoliators this summer may indicate rising populations and increased defoliation over the next few years. A recently revised guide to aerial sprays for landowners is now available.Cover page of the updated aerial spray guide. Continue reading “Revised aerial spray guide now available” →

Interactive HRD stump treatment guidelines available online

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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!