Forest Health News

Oak health issues in summer 2019

Posted on by margueriterapp

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

The most commonly reported forest health issue in recent weeks has been unhealthy looking oaks. Symptoms ranging from rapid mortality to gradual decline to superficial have been observed on all species of oak this summer.

affected oak tree with dead leaves in lower half of crown

White and bur oaks are being impacted by a variety of health issues in late summer 2019, including fungal leaf infections and bur oak blight. Symptoms are most severe in the lower half of this tree’s canopy. Credit: DNR Forest Health.

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It’s Firewood Awareness Month: do you know what your options are?

Posted on by margueriterapp

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

Most people know that using locally-sourced firewood helps prevent the spread of invasive pests and diseases. What may be less well known are the processes for finding local sources of firewood or learning where and how you can collect it yourself. During Firewood Awareness Month, we want to share what options are out there so you can take steps to protect the places you love.

Firewood isn't dead - infested firewood can carry insects and diseases to new places

Infested firewood can carry invasive insects and diseases to new places. Buy or gather firewood where you will use it or buy firewood that has been certified as heat-treated and free of pests and diseases. Credit: dontmovefirewood.org.

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Continued decline & mortality on lowland sites

Posted on by margueriterapp

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

Site visits and aerial surveys conducted in parts of Wisconsin during July and August have found that tree decline and mortality were common in numerous lowland forest stands. 

Heavy tree mortality in a lowland site where standing water was present on July 31. Surviving trees can be found on adjacent higher grounds. Credit: Bill McNee.

Heavy tree mortality in a Manitowoc County lowland site where standing water was present on July 31. Note the surviving trees on higher ground and in adjacent stand. Credit: Bill McNee.

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Native vine thrives with wet Wisconsin summer

Posted on by margueriterapp

Have you noticed a fast-growing vine with fragrant flowers on your trees and shrubs this summer? The plant began to flower a few weeks ago, drawing attention and concern from residents around the state.

Wild cucumber blooms with yellowish-white fragrant flowers. Credit: Susan Mahr.

Wild cucumber blooms in mid- to late summer with yellowish-white fragrant flowers. Credit: Susan Mahr.

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Spruce needle rust in the north

Posted on by margueriterapp

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

Spruce needle rust is showing up in some northern counties. This rust fungus infects current year needles of most spruce species, including white and black spruce, with blue spruce being most severely impacted.

Spore-producing structures of the fungus emerging from the spruce needles.

Spore-producing structures of the fungus emerging from infected spruce needles.

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Red branches on white pine?

Posted on by margueriterapp

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

Large white pines with red wilting branch tips may be caused by a very tiny insect called white pine bast scale (Matsucoccus macrocicatrices). The branch mortality that follows may be caused by an insect/disease complex that is still relatively new to Wisconsin.

Branch tips throughout the white pine tree are wilting and turning brown due to white pine bast scale feeding.

Feeding by the white pine bast scale is causing branch tips throughout the tree to wilt and turn red this summer.

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Reports of redheaded pine sawfly colonies

Posted on by margueriterapp

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

Colonies of the redheaded pine sawfly have been reported in northeastern Wisconsin. They can cause significant defoliation in some situations and may warrant control if larval populations are large.

This native insect feeds in groups with many sawfly larvae together on a single needle or branch.

This native insect feeds in groups with many sawfly larvae together on a single needle or branch.

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Oak slug sawflies on oak leaves

Posted on by margueriterapp

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

Oaks in some northern counties are experiencing defoliation from oak sawflies this year. These native defoliating insects are small, hairless, semi-transparent larvae or “slugs” that feed on oak leaves.

Oak slug sawflies feed in groups on the undersides of oak leaves.

Oak slug sawflies feed in groups on the undersides of oak leaves.

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Barklice are nothing to worry about

Posted on by margueriterapp

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

Barklice tend to congregate in large groups on trees, which can lead some people to worry about tree health, but they are actually quite harmless.

Immature barklice congregated on bark. Striped abdomens are easy to see before the insects mature into adults and develop wings.

Immature barklice congregated on bark. Striped abdomens are easy to see before the insects mature into adults and develop wings.

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