oak wilt

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There was snow on the ground Thursday in the Northwoods but a DNR spokesperson says be careful about doing pruning on oak trees  April through July.

Every county in Wisconsin with the exception of Forest, Iron and 9 other counties have the tree disease Oak Wilt. Paul Cigan is a DNR plant pest and disease specialist....


A deadly disease in oaks has been found for the first time in Price county. Oak Wilt was found by the DNR in two red oak trees in the town of Elk, north of Phillips.

No one was available from the DNR to discuss the finding on Friday, but U.S. Forest Service silvaculturalist Jerry Van Cleve says it has been found in the southern two-thirds of the state, but it has been spreading northward and is considered an invasive species...

Wisconsin DNR

It might seem strange, but a tree expert says winter is the best time to prune trees to help prevent oak wilt.

Oak wilt is a tree fungal disease that chokes off an oak trees vascular system, like plugging up a person's veins and arteries. An infected tree will die from the top down. Beetles also spread the disease.

Avoid Oak Wilt: Don't Prune Too Soon

Apr 1, 2014
Ronald Billings / Texas Forest Service

Now that it’s April, experts say don't prune oak trees until after July…if you want to keep them safe from the oak wilt pathogen.  Oak wilt is a deadly fungus that gets transmitted through tiny sap beetles. 

DNR Forest Health specialist Brian Schwingle says oak wilt works in a similar way as Dutch elm disease, which devastated North American elm populations in the 20th century.  Both are fungal diseases spread through beetles.  But Schwingle says out of the two, oak wilt is much easier to prevent. 

Oak Wilt Arrives in Minocqua-Woodruff

Nov 20, 2013
Ronald Billings / Texas Forest Service

A lethal tree disease has been found for the first time in near Woodruff.  Oak wilt is prevalent in southern and central Wisconsin.  But tests have confirmed its presence in the Northern Highland American Legion State Forest. 

DNR Forest insect and disease Specialist Brian Schwingle says the finding is significant.               

“It’s concerning that we found it on our largest state property, the Northern American Legion state forest, where oak is an extremely valuable tree.”