A tree shows fruiting bodies of Heterobasidion root disease at its trunk. / Photo Credit: Wisconsin DNR

By Kyoko Scanlon, DNR Forest Pathologist
Kyoko.Scanlon@wisconsin.gov or 608-235-7532

Heterobasidion root disease (HRD), a destructive fungal disease, continues to be found in Wisconsin.

The Wisconsin Department of Natural Resources (DNR) has confirmed detections in several stands over recent months.

The DNR’s 6-mile and 25-mile buffer zone maps have been updated based on the locations of the newly confirmed stands. The most notable changes due to expanded buffer zones have taken place in Door, Marinette, Milwaukee and Pierce counties.

A map of Wisconsin shows the most up-to-date Heterobasidion root disease infections and the 25-mile buffer zones around them. / Map Credit: Kyoko Scanlon, Wisconsin DNR

HRD stump treatment guidelines are used for forest management activities on state lands managed by the Wisconsin DNR and are recommended on county forests and private lands. Under certain conditions, as described in the guidelines, treatment of pine and/or spruce stumps of merchantable size within 25 miles of detection is recommended.

Newly included areas have a one-year grace period for implementing the guidelines on DNR lands. Currently, three areas are under this grace period.

To keep up with the disease’s expansion, check out the HRD web map viewer for up-to-date 25-mile buffer zones and areas currently under grace periods.

HRD was first observed in Wisconsin in 1993 and is now known to occur in 31 of the state’s 72 counties. In Wisconsin, HRD is known to infect and kill red, white and jack pines, white and Norway spruces, balsam fir and red cedar.

HRD-infected trees exhibit reduced height, shoot and diameter growth and thinner foliage. Symptoms progress over several years and result in mortality. Symptoms typically appear 3-8 years after a stand is thinned.