Root rot fungus infects conifers in Capitol State Forest campground

Photo of fallen tree near outhouse in Mima Falls Campground.
Recently, this tree—infected with laminated root rot—blew down in a storm at Mima Falls Campground. Fortunately, no one was in the outhouse at the time! Photo: Florian Deisenhofer/DNR.

DNR scientists who specialize in tree health have discovered a widespread infection of laminated root rot in Douglas fir, grand fir, and hemlock trees in Mima Falls Campground and the trailhead parking area in Capitol State Forest. Trees infected with this disease pose a significant threat to public safety because the fungus destroys the roots.

For safety reasons, all but a few of the trees in the campground and trailhead will be removed this winter while the area is closed for the season.

“Trees infected with laminated root rot are highly unstable and can easily fall over as they lose root strength,” said Florian Deisenhofer, Natural Resource Scientist with DNR’s Pacific Cascade Region. “This can even occur when trees are still alive and have no observable symptoms. The disease creeps from root to root through the soil and can persist for decades on a site, making forest management very difficult.”

DNR will conduct a small timber sale to remove the trees early next year. Harvest is scheduled to begin in early February. The goal is to complete the harvest by mid April, in time for the reopening of the campground and trails on May 1.

After the trees are removed, crews will replant the area with western red cedar, which are not susceptible to the disease. Hardwood trees such as red alder and bigleaf maple are also resistant to laminated root rot.

The disease—known scientifically as Phellinus weirii—can also create a secondary impact. Douglas fir bark beetles have attacked some of the stressed trees at the campground, killing the trees and creating hazardous snags.

With the impending timber sale at Mima Falls campground and trailhead, DNR is also temporarily closing access to the Mima Falls trail this winter. For an alternative access to the Mima Falls trail, start at the Margaret McKenny campground just ¼ mile north of Mima Falls campground.

For more information, contact Nick Cronquist, Pacific Cascade Region Outreach and Volunteer Coordinator, at 360-480-2700.

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