New University of Minnesota research offers land managers a practical strategy for keeping invasive buckthorn from returning: remove the shrub and sow native grasses and wildflowers as early as possible.
The findings, recently published in Forest Ecology and Management, show that timely restoration with native plants soon after buckthorn removal can significantly improve control of common buckthorn, one of Minnesota's most aggressive invasive species. Managing buckthorn is especially challenging because it can easily bounce back after removal, making effective long-term control strategies essential to prevent reinvasion.
The research was funded by the University's Minnesota Invasive Terrestrial Plants and Pests Center, supported by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).
Researchers from the Cover It Up! Project, part of the Minnesota Invasive Terrestrial Plants and Pests Center, have previously shown that seeding native grasses and wildflowers can effectively limit buckthorn returning from seed, but a major question remained: do managers need to remove buckthorn resprouts immediately, or can they wait a few years and still get the same benefits of native seeding? To test this, the researchers compared forest understories where herbicide was used to control resprouts soon after initial management against those where herbicide was delayed a few years.
They found:
- After initial buckthorn removal efforts, treatment the following year with a foliar (leaf) application of the herbicide fosamine ammonium (Krenite) is an effective way to kill many plants.
- Following up with a second application two years later nearly removes all buckthorn.
- Waiting multiple years before the first follow-up treatment is less effective at killing buckthorn.
- Adding native plants after the first treatment helps suppress buckthorn by competing with their seedlings. This method is especially effective in areas without a dense tree canopy.
"There is no silver bullet for defeating buckthorn, but our work shows that control is possible with hard work and patience," said lead author Andrew Kaul, a former postdoctoral researcher in the College of Food, Agricultural and Natural Resource Sciences, currently with the Missouri Botanical Garden.
These results demonstrate that seeding native species immediately after management is more effective than waiting until fall or winter, which is when most buckthorn management typically occurs.
"This work shows how treating resprouts with herbicide and seeding early on in management is key to successful restoration efforts," said Mike Schuster, a researcher in the College of Food, Agricultural and Natural Resource Sciences.
The research team is now testing different methods, rates and seed mixes for restoring native wildflowers and grasses in forest understories and measuring other benefits of this type of management for nature and society.
About the College of Food, Agricultural and Natural Resource Sciences
The University of Minnesota's College of Food, Agricultural and Natural Resource Sciences strives to inspire minds, nourish people, and sustainably enhance the natural environment. CFANS has a legacy of innovation, bringing discoveries to life through science and educating the next generation of leaders. Every day, students, faculty, and researchers use science to address the grand challenges of the world today and in the future. CFANS offers an unparalleled expanse of experiential learning opportunities for students and the community, with 12 academic departments, 10 research and outreach centers across the state, the Minnesota Landscape Arboretum, the Bell Museum, and dozens of interdisciplinary centers. Learn more at cfans.umn.edu.
About the Minnesota Invasive Terrestrial Plants and Pests Center
The Minnesota Invasive Terrestrial Plants and Pests Center was founded by the Minnesota Legislature to research the prevention, detection and control of terrestrial invasive species. MITPPC researchers use transformative science to prevent and minimize the threats posed by land-based invasive plants, pathogens, and pests. Founded in 2015, MITPPC is the only research center of its kind in the country, and the center's work to protect the state's native prairies, forests, wetlands, and agricultural resources benefits all of Minnesota and beyond. MITPPC receives program support from the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources. Learn more at mitppc.umn.edu.
