By Angela Gupta, UMN Extension Forester, agupta@umn.edu
Butternut trees are a listed threatened species in Minnesota because of invasive butternut canker. Starting in August, UMN Extension Forestry is launching a participatory science project asking you, woodland owners, and forestry professionals and others interested in Minnesota’s natural resources to look for native butternuts, assess the health of individual trees, and report the “healthy” trees to iNaturalist. You can learn more by visiting this webpage: https://z.umn.edu/betteringbutternut
Butternut is a native tree in the same family as black walnut. It has large lemon shaped nuts that grow in clusters of two to six. The nuts can be shelled and eaten or prepared like nut butter. Like walnuts, the husks were used by early settlers to dye fabric for clothes. Butternut wood is a golden brown color, not as dark as walnut but a lovely high-value hardwood sometimes used for furniture. The wood is softer than walnut so it’s prized by wood carvers for its warm color and easier workability. Even before the invasive butternut canker killed most butternut trees in eastern North America, it was only a small part of a complex mixed hardwood forest. Likely, in part because it was never a species that sold in large volumes, its slow death to the canker went unnoticed and generally unmanaged for decades. Because of this slow decline from butternut canker, butternut is now on MN DNR’s Threatened and Endangered Species list.
If you’re interested in learning more, please review the Bettering Butternut webpage for details. Identification between butternut, non-native Japanese walnut, and a cultivated hybrid Buartnut is very tricky and may eventually require genetic testing. In addition to paying close attention to several identification characteristics, we’re asking volunteers to look at the health of the tree. Volunteers will need to assess the amount of butternut canker present at the base and include several identification and health assessment pictures in their iNaturalist reports.
We hope that high-quality iNaturalist reports will provide researchers with information on new “healthy” native butternut trees that may eventually be genetically tested and possibly used to propagate canker-resistant native butternuts that could one day be reintroduced to our forests.
Photos by UMN Extension.