RIB MOUNTAIN, Wis. (WSAU) -- Oak Wilt has been found in some trees at Rib Mountain State Park.
DNR forest health specialist Mike Hillstrom says the tree killing fungus has been found in Marathon County before, but not at Rib Mountain State Park. He says they run some tests on some trees that didn’t look healthy. “In the fall, we noticed some trees that lost their leaves early, and those trees also had some storm damage from earlier in the year, and that’s a way that these trees classically get oak wilt, so we went out and took some samples from the trees and our lab tests confirmed that the trees had oak wilt.”
Hillstrom says Oak Wilt is a fungus that spreads when the spores are spread by insects feeding on damaged or pruned branches. “The beatles come in to feed, and oak wilt can get into a tree that way, and then once the fungus is in the tree, it can grow through roots from a tree to another tree of the same type.”
Hillstrom says they will be removing the infected trees soon to prevent the disease from spreading. “We have four trees that we’ve confirmed that are infected. Two of them are basically in one area, and the two trees are basically right next to each other. And then there’s another area maybe 200 yards away with two more trees.”
While oak wilt affects all oak species, it is most severe in the red oak group. Hillstrom says to prevent the spread of oak wilt, prune or remove oak trees between November and April 15th when the threat of transmission is lowest.
There’s more information about caring for oak trees at the DNR’s web site. Type “oakwilt” in the search box.