Disease

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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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”

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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Fall is a great time to look for HRD

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

Considered one of the most destructive diseases of conifers in the northern hemisphere, HRD is very difficult to eradicate once established. Infestation of a conifer stand may significantly impact stand management, making early detection of the disease extremely important.

new white growth on old HRD conk

HRD fruit body with new white growth on infested stump. Credit: DNR Forest Health.

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Oak health issues in summer 2019

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?

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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Spruce needle rust in the north

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?

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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