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Check your trees for EAB and plan for spring

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

The cold winter months are a great time to think about emerald ash borer and whether ash trees in your yard are suitable for treatment. The pest is currently the most damaging threat to trees in Wisconsin, killing more than 99 percent of the ash trees it infests.

Two side-by-side images depicting different stages of flecking on ash trees - on left side is light flecking in the upper canopy of a tree, on the right side is more severe flecking that extends down the trunk of the tree

Woodpecker flecking is an early sign of EAB infestation when it appears in the tops of trees (left). As the infestation progresses, flecking continues down the trunk and into lower parts of the crown (right).

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Upcoming forest health events

Learn more about forestry and forest health issues with these upcoming events in February and March! We link to conference brochures and webpages where you can find detailed information, including registration prices and deadlines where applicable. Continue reading “Upcoming forest health events”

Oak wilt found in Forest Co. and northern townships

By forest health specialists Paul Cigan, Hayward, paul.cigan@wisconsin.gov, 715-416-4920 and Linda Williams, Woodruff, linda.williams@wisconsin.gov, 920-360-0665

Oak wilt has been found for the first time in Forest County and several new northern townships in 2019. These previously undocumented infections were detected using a combination of ground surveys, forester and landowner reports and aerial survey flights. This deadly fungal disease of red oaks has now been confirmed in 65 of Wisconsin’s 72 counties.

Updated oak wilt detection map shows new county and township detections described in text.

Oak wilt detection map as of January 1, 2020.

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Protect your trees from disease by pruning when they have no leaves

By Paul Cigan, forest health specialist, Hayward, paul.cigan@wisconsin.gov, 715-416-4920

With the new year upon us, healthy lifestyle habits are sure to be on many people’s minds as they plan for changes in diet and exercise. The new year is also the perfect opportunity to make healthier choices for trees! Winter is the ideal time for tree pruning while avoiding harmful, disease-carrying pests such as the tiny beetles that carry oak wilt from one tree wound to another.

Woman pruning a tree with no leaves on it.

Pruning during winter is less likely to invite unwanted, disease-carrying pests like the beetles that carry oak wilt from one tree to another. Credit: sasapanchenko.

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2019 Forest Health Annual Report now available

Forest health annual report now available for 2019.

The Forest Health Annual Report summarizes notable impacts for that year of pests, diseases and weather on the health of Wisconsin’s forests. The report is a collaborative product created by DNR forest health specialists from around the state. It outlines the damage and spread of both native and invasive pests and diseases during that year and puts these into context of observations from previous years. Management programs and their results are also described. Highlights from the 2019 annual report include:

  • Dramatically increased decline and mortality from emerald ash borer in southern WI
  • New county and township detections of oak wilt
  • Precipitation record and major storm damage
  • Summary of state nursery studies on Diplodia sapinea, galls on jack pine seedlings, and testing new fumigants to replace methyl bromide

This year’s annual report is available on the DNR forest health homepage. Previous annual reports, including historical reports dating back to 1951, are archived and available upon request. Contact your local forest health specialist if you’d like digital copies of any archived annual reports.

Snow fleas spring to surface in early December

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

Snow fleas are a species of springtails that are active during winter and are generally found in groups where their dark-colored bodies stand out against the white snow. While often observed in late winter or early spring, they also come to the surface on warm winter days, making an early December appearance in west central Wisconsin something to note but not altogether unusual given the relatively warm weather in the area. 

Tiny flecks against an impression in snow are hundreds of snow fleas at surface.

Easily mistaken for specks of dirt or debris, snow fleas are tiny soil-dwelling animals that gather on the surface of snow on warm winter and spring days.

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New map illustrates damage from EAB

Forest health staff recently produced a map that highlights a gradient of damage from southeastern to northwestern Wisconsin, which roughly corresponds to the length of time EAB has been present in these parts of the state. Whatever the level of damage, homeowners and landowners should consider treating healthy ash, including trees that have responded well to previous treatments, or removing declining, untreated ash before they become hazardous and even more costly to remove.

County-level map of damage from EAB to ash tree populations in 2019

County-level assessment of damage to ash population by emerald ash borer, 2019.

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Invasive plants, ticks and you

Most people are familiar with the impacts of invasive plants to natural areas, but did you know that invasive plants can be hazardous to human health? Did you also know there is a new app available to learn about tick activity near you and help researchers by recording your own tick encounters?Forested setting with tree in foreground and sign attached to tree that says beware of ticks. Continue reading “Invasive plants, ticks and you”

Leaf beetle spreading in southern Wisconsin

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

Viburnum leaf beetle is a relatively new invasive insect from Europe that feeds on the leaves of viburnums and causes mortality after a few years of repeated defoliation. Along with the killing of native viburnum species, which are highly susceptible to the pest, impacts include a higher likelihood of invasive species becoming established following the mortality. Continue reading “Leaf beetle spreading in southern Wisconsin”

Pine wood nematode in Waushara County

By Alex Feltmeyer, forest health specialist, Plover, alexandra.feltmeyer@wisconsin.gov, 715-340-3810

Pine wood nematode (PWN) was recently found to be infecting Scotch pine in Waushara County. Symptoms of pine wood nematode include rapid crown browning (within 3 months) in late summer, rapid drying of wood and presence of blue-stain fungi in the wood.

Row of pine trees with browning needles from pine wood nematode infestation.

Symptomatic trees dying from pine wood nematode. Photo by Alex Feltmeyer. 

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