By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665
Wisconsin has a few leaf-eating caterpillar species that are out early in the spring. Forest tent caterpillars, eastern tent caterpillars and spongy moth caterpillars cause varying levels of tree damage and are often mistaken for one another.
Forest tent caterpillars congregating on the trunk of a tree. Photo: Wisconsin DNR
Continue reading “Hairy Spring Caterpillars – Which One Do You Have?”
By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov, 920-360-0665
Have you ever seen an oak wilt fruiting body? Oak wilt is a fungal disease that kills trees in the red oak group (northern red oak, northern pin oak, black oak and other oaks with points on their leaves). Trees in the white oak group (white oak, burr oak, swamp white oak and other oaks with rounded leaves) are more resistant to the disease, but branches or branch tips can still be killed.
Oak wilt pressure pads can create a crack in the bark, allowing beetles to get into the spores. Photo: Wisconsin DNR
Continue reading “On The Lookout For Oak Wilt Fruiting Bodies”
By Michael Hillstrom, DNR Forest Health Specialist, Fitchburg, michael.hillstrom@wisconsin.gov
Typical browning leaf symptoms of red oak trees infected with oak wilt. Photo: Wisconsin DNR
Now is the time to watch for oak wilt! Symptoms typically appear in southern Wisconsin in late June and in northern Wisconsin during July. Watch for browning leaves starting at the top of the canopy and progressing downward. Most leaves will fall from infected trees as they die, typically within two to four weeks.
Several management methods are available to contain oak wilt pockets, so consult your local forest health specialist for guidance on your best options.
The forest health team is also working to evaluate new control methods. Rapid response is currently being tested to more formally evaluate if a new oak wilt infection in a single tree can be stopped before it reaches the roots and spreads to nearby oaks. There is observational data that this method works, but more formal tests are desired. Continue reading “June To October: Oak Wilt Watch!”
By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665.
As you begin your summer travel, you may notice that many white pine trees along northern Wisconsin roadways have a lot of brown needles on them. Although it may seem concerning, most of these trees are sending out new needles as we speak.
Different conifer species can be impacted differently by salt spray. The white pine in the middle also shows lower branches that are green because they were protected by snow. Photo: Wisconsin DNR.
Continue reading “I Spy… Browning White Pine Stands Along Roads”
By Ethan Wachendorf, DNR Forest Health Lab Technician, Fitchburg, ethan.wachendorf@wisconsin.gov or 608-273-6276
Have you noticed orange, jelly-like growths on cedars this spring? These growths may look like tiny octopus creatures with legs extending all directions, but they’re actually spore horns caused by a fungus.
Orange jelly-like spore horns caused by cedar-apple rust fungus. Photo: Wisconsin DNR
Continue reading “When It Rains, It Spores! Orange Spore Horns Emerge”
By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665.
Introduced basswood thrips are tiny, invasive insects that feed inside tree buds in early spring. Leaves are then deformed when they expand and can look like frost or wind has damaged them.
An adult introduced basswood thrips on the underside of an emerging basswood leaf. This photo is enlarged under a microscope. To the naked eye, they appear as tiny black specks on the underside of the leaf. Photo: Wisconsin DNR
Continue reading “Basswood Thrips: Tiny Terrors Of Basswood Leaves”
By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665.
White trunk rot (Phellinus tremulae), sometimes called aspen trunk rot, is a fungus that causes decay columns to form in aspen. The fungus enters the tree through branch stubs, wounds or small dead branches that remain on the tree. Perennial conks, or fungal bodies, then grow from these sites.
White trunk rot causes decay in aspen trees. Note the conk (fruiting body) from the fungus on the left side of the pic. Photo: Wisconsin DNR
By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665.
Maples
Have you noticed any maple trees that appear brown or reddish and have fewer leaves than usual? The seeds, not the leaves, make the tan/red color. Those seeds are so plentiful this year that they can easily be spotted from a distance.
Maples with heavy seed crops may appear tan or reddish due to the color of the seeds and having very few green leaves in the canopy. Photo: Wisconsin DNR.
Continue reading “Slow Oaks And Maples With Too Many Seeds And Not Enough Leaves”
By Brenna DeNamur, DNR Forest Health Outreach Specialist, Madison, Brenna.DeNamur@wisconsin.gov
The Forest Health Team has made many changes since the spongy moth’s* (formerly known as gypsy moth) new name debut in March. Earlier this month, we launched the new and improved Spongy Moth Portal!
By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665 & Paul Cigan, DNR Forest Health Specialist, Hayward, Paul.Cigan@wisconsin.gov, 715-416-4920
Emerald ash borer (EAB) has been detected for the first time in Forest County in the Town of Armstrong Creek and Ashland County in the City of Ashland. The Forest County detection was most likely a natural expansion of other infestations in Florence and Marinette counties.
This Forest County tree was infested with EAB top to bottom. Photo: Wisconsin DNR
The Ashland County detections appear to be isolated infestations likely spread through the transportation of firewood or logs. Several large green ash stands in the City of Ashland show advanced infestation signs.
EAB was first found in Wisconsin in 2008. There are now just seven counties where EAB has not yet been identified. EAB was federally deregulated as of January 2021. In 2018, Wisconsin instituted a state-wide quarantine. This discovery in Forest and Ashland counties will result in no regulatory changes.
Please visit the interactive Wisconsin EAB detections map to see where EAB has been reported. Follow the map’s instructions if you know of an infested area not on the map. Continue reading “EAB Identified For The First Time In Forest And Ashland County”
