Common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus) are both regularly found in Minnesota’s forests. Many woodland stewards spend time and resources managing buckthorn by cutting, pulling, forestry mowing, treating with herbicide, or using goats.
Effective and lasting buckthorn management usually takes many years and a combination of treatment methods to remove these troublesome shrubs and nurture a forest that is more resistant to future re-infestation.
Now imagine a future in which introducing one or more species of fungi to a site helps control buckthorn, thus helping keep these aggressive and ecosystem-altering plants in check. Researchers and funders are hoping to make this dream a reality.
With funding from the Minnesota Invasive Terrestrial Plants and Pests Center (MITPPC), two research teams have launched projects to better understand how native fungi commonly found on buckthorn may help keep this invasive plant in check.
Pablo Olivera Firpo, a researcher in the University of Minnesota Department of Plant Pathology, and his team are studying which type of crown rust infects common buckthorn and the fungi’s impact on buckthorn seedlings.
Plant pathology professor Robert Blanchett hopes to identify which fungi are colonizing and killing buckthorn, which fungi can prevent stump resprouting, what effects these fungi have on other vegetation, and how best to apply biocontrol fungi in the woods.
More on these research projects can be found at the MITPCC website. These projects are just getting started but it’s exciting to think there could be another tool to enhance forest resilience.
Putting samples to the test
While cutting and treating buckthorn stumps in his woodland in October of 2023, Extension forester Gary Wyatt noticed many smaller buckthorn trees had died when reaching between 5 to 7 feet tall. Some of the trees that were still green were very easy to pull up, which is not typical. “Previously I could only pull up maybe a 1- to 2-foot buckthorn seedling, not trees over 3 feet tall,” he said. He also noticed white fungus on some of the tree stems and roots.
Gary had heard of the MITPPC research on fungus possibly affecting buckthorn growth, so he contacted UMN plant pathology researcher Ryan Franke who agreed to take a look at them. He pulled up a few of the dead trees and brought them to the University of Minnesota St. Paul campus where Ryan took four tree samples. After a few days, Ryan emailed him to report that he found 12 different fungi on the buckthorn samples. “I thought that was amazing!” Gary said. “This research is important. We need to learn more about the fungi that may be affecting buckthorn and make sure they are not causing a problem with native or desirable trees and plants.”
If you think you’ve found crown rust (Puccinia spp.) on buckthorn leaves or fungi on buckthorn stems or roots, please submit your observations:
It is always helpful to submit observations using the iNaturalist app, where researchers can also find and use the data.
More about buckthorn, fungi and woodland stewardship
If you’re interested in learning more about the complicated ecosystem interactions of buckthorn and several other invasive pests, check out the video Tangled Ecosystem. To dive into the fascinating world of fungi, I recommend the book Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures by Merlin Sheldrake.
Buckthorn management is often a first step for overall woodland stewardship. To learn more about how to nurture the woods after initial buckthorn removal work check out the great resources produced by the MITPPC-funded Cover it Up! Project.
Also of interest for woodland stewards is Extension’s climate-ready woodlands lists featuring climate-resilient trees and plants that benefit Minnesota’s microfauna.
Funding on the November ballot
The Environment and Natural Resources Trust Fund (ENRTF) is generated from the Minnesota State Lottery. Minnesota voters allocated these resources in 1988 "for the public purpose of protection, conservation, preservation, and enhancement of the state's air, water, land, fish, wildlife, and other natural resources." The fund supports many vital natural resource conservation programs, including MITPPC. This November Minnesota voters will decide whether to continue funding the ENRTF.