By Kyoko Scanlon, DNR Forest Pathologist, Kyoko.Scanlon@wisconsin.govor 608-235-7532 and Elly Voigt, DNR Forest Health Communications Specialist and Lab Technician, Eleanor.Voigt@wisconsin.gov or 608-273-6276

Oak wilt is a serious disease that occurs when insects carrying oak wilt fungal spores land on a healthy oak tree’s fresh wound. To prevent oak wilt infections, it is important to avoid pruning, wounding and harvesting oaks when these insects are abundant, generally April through July.

Predicting exactly when these insects start to emerge in the spring can be difficult as their emergence is highly weather-dependent, and spring weather varies significantly from year to year.

The good news is that a new online interface is now available to provide users with localized information about the emergence status of the two most important insects that transmit oak wilt in Wisconsin. The interface uses a degree-day model constructed from insect trapping data and actual weather data, which helps refine the beginning of the periods when pruning, wounding, or harvesting oaks should be avoided.

This interface runs on the UW Ag Weather website and is easy to use. You only need to enter two pieces of information on the homepage: the location and the date of interest.

The Wisconsin Department of Natural Resources (DNR) created a user guide and video tutorial for this interface, available on the DNR’s oak wilt webpage and on the  interface itself.

Please note that this interface intends to supplement, not replace, the calendar dates specified in the DNR’s oak harvesting guidelines. This interface provides degree-day-based information about the beginning of the oak wilt high-risk period, not the end of the high-risk period. Currently, the interface is not built to predict future growing degree-day information. 

If you have any questions about this interface, please contact your Regional DNR Forest Health Specialist or Kyoko Scanlon, DNR Forest Pathologist, at Kyoko.Scanlon@wisconsin.gov.