Disease

Rhizosphaera needlecast on balsam fir

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Rhizosphaera needlecast of fir produces rows of round black fruiting bodies on the needles. Photo by Colton Meinecke.

Rhizosphaera needlecast of fir produces rows of round black fruiting bodies on the needles. Photo by Colton Meinecke.

Rhizosphaera needlecast was found on balsam fir in Shawano County, with additional reports from Todd Lanigan (West Central WI) and Paul Cigan (Northwest WI). It causes chlorosis in the needles which drop off prematurely, giving the tree a thin appearance. This disease is related to the Rhizosphaera needlecast of spruce which you may be more familiar with. Literature indicates that it is most common on fir trees in shaded damp areas, or on trees that are under stress from other issues. You will see small black fruiting bodies on the undersides of the needles, although what really stands out is the thin foliage or off-color needles compared to other unaffected trees. 

Needles from the previous year have turned brown and will drop off prematurely due to Rhizosphaera needlecast.

Needles from the previous year have turned brown and will drop off prematurely due to Rhizosphaera needlecast.

Additional info can be found in this pest alert from the Forest Service.  

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Oak wilt and hickory mortality Forest Health Fact Sheets are available

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The forest health program is in the process of updating some of our publications as Forest Health Fact Sheets. These publications offer biology, impact, prevention and management information about specific threats to forest health. Our new oak wilt fact sheet and hickory dieback and mortality fact sheet are currently available on the DNR’s forest health oak wilt and bark beetle webpages and will be available in the DNR’s online publications catalog  in the near future. Enjoy!

Written by: Mike Hillstrom, forest health specialist, Wisconsin Dells (Michael.Hillstrom@Wisconsin.gov), 715-459-1371.

Phomopsis galls on northern red oak

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Phomopsis galls are woody, lumpy swellings on the branches and main stem of this northern red oak tree.

Northern red oak with many phomopsis galls on the branches and on the main stem.

Phomopsis galls are large, woody galls caused by a fungus and can be unsightly on the branches of trees (people often notice them in the winter when leaves are off). They occur in hickories, maples, oaks and a few other species. In northeastern Wisconsin, I find them most commonly on hickory, but in some areas northern red oaks can be heavily galled. Counties where I’ve seen these large galls on northern red oak include Oconto, Oneida, Shawano and Vilas. Continue reading “Phomopsis galls on northern red oak” →

Invasive insects and disease awareness month

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Vin Vasive is the spokesman for invasive insects at USDA APHIS. He is made up of invasive species. This USDA APHIS poster was designed by Deb Levy Creative.

Vin Vasive is the spokesman for invasive insects at USDA APHIS. He is made up of invasive species. This USDA APHIS poster was designed by Deb Levy Creative.

April is invasive plant pest and disease awareness month, and May 21-27 is EAB awareness week.

It’s spring, and a good time to remember that invasive species can be easily moved long distances by unsuspecting citizens; maybe even you! All it takes to potentially start a new infestation is to move things we often like to take with us, but don’t know are a problem:

  • firewood,
  • infected or infested plant material,
  • an infected or infested piece of fruit, or
  • even a decorative piece of northwoods style furniture that hasn’t been properly treated to kill pests hiding inside.

Take a moment to think about whether you are unknowingly moving items that could harbor pests. The Hungry Pests website lists things you can do to prevent the spread of invasive species, whether you’re a birdwatcher, gardener, hunter, logger, or anyone. Check it out! While you’re there check out some short videos of their “spokesman” Vin Vasive, who has gotten much creepier over the years. 

Help spread the word

Coming up, May 21-27 is emerald ash borer awareness week, which is right before the Memorial Day holiday, when lots of travelling, camping, and opening up of summer cabins occurs. The Don’t Move Firewood website has a nice video of how to identify an EAB infested tree. More detailed videos are also available at dnr.wi.gov, keyword “forest health.” If you would like some examples of outreach tools or publications you can use to promote EAB awareness, check out the Don’t Move Firewood website; there you’ll find games for kids, an EAB craft project, videos, press releases, and news articles from past years. 

Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@wisconsin.gov), 920-662-5172. Categories: FH, UF. Tags: Statewide FH, Insect, Pest

Oak wilt found in Price County, plus prevention steps

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This map shows the known distribution of oak wilt in Wisconsin by county and townships as of December 1, 2016.

Map of the known distribution of oak wilt in Wisconsin as of December 1, 2016.

Oak wilt, a deadly fungal disease affecting red oaks, was confirmed for the first time in Price County in 2016. In addition to the new county find, the disease was also confirmed in various townships in northern Wisconsin counties where we already knew oak wilt was present.

The map in the oak harvesting guidelines was updated based on the find.

Oak wilt is commonly found in the southern two-thirds of the state, but has been creeping northward. The disease was found for the first time in 2010 in Oneida County, in 2012 in Lincoln, Sawyer, and Vilas counties, in 2013 in Rusk County, and in 2014 in Washburn County. Oak wilt has been confirmed in all Wisconsin counties except Ashland, Bayfield, Calumet, Door, Douglas, Forest, Iron, Kewaunee, Manitowoc, Sheboygan, and Taylor.

Read more about oak wilt prevention in the news release from March 21, 2017: Protect oak trees from oak wilt by waiting until after July to prune.

Written by: Kyoko Scanlon, forest pathologist, Fitchburg (Kyoko.Scanlon@Wisconsin.gov), 608-275-3275.

Financial assistance is available for controlling invasive species.

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Looking for a financial assist in your efforts to control invasive species?

The Wisconsin Invasive Species Council website lists 61 different grant opportunities that are available from Federal and State agencies as well as private foundations. The list is searchable by applicant (tribe, government agency, company, non-profit, individual) and type of invasive organism (plant, animal, aquatic, invertebrate, disease). All but one has a link that takes you to more information or a contact person.

Why not take a few moments to explore these opportunities?

Written by: Michael Putnam, invasive plants program specialist, Madison (Michael.Putnam@wisconsin.gov), 608-266-7596.

Stump treatment to prevent heterobasidion root disease (Annosum)

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Applying a preventative treatment to a fresh pine stump using a backpack sprayer.

Applying a preventative treatment to a fresh pine stump using a backpack sprayer. Photo by: Linda Williams, WI DNR.

There are currently two products available to treat fresh pine stumps to prevent new infections of heterobasidion root disease (HRD), which was previously called annosum. The products are Cellu-Treat and Rotstop-C. Both are water soluble and can be sprayed on the stump. Sporax, a granular/powder product, was previously available but is no longer being manufactured. If you still have a supply of Sporax you can continue to use it. The one-page factsheet on HRD (Annosum) has been updated with information on where to purchase the available products.

For more information on Cellu-Treat and Rotstop-C please check out these websites:

Written by: Kyoko Scanlon, forest pathologist, Fitchburg (Kyoko.Scanlon@Wisconsin.gov), 608-275-3275.