|SARTAIN, BRADLEY - Mississippi State University|
|TURNAGE, GRAY - Mississippi State University|
|MARKO, MICHELLE - Concordia College|
Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2016
Publication Date: 7/1/2016
Citation: Madsen, J.D., Sartain, B., Turnage, G., Marko, M.D. 2016. Management of flowering rush in the Detroit Lakes, Minnesota. Journal of Aquatic Plant Management. 54(2):61-67.
Interpretive Summary: Flowering rush is an invasive plant to lakes and wetlands in the United States that can grow either emergent or submersed in the water. We studied the management of flowering rush in the Detroit Lakes, Minnesota, to test whether an herbicide use pattern of submersed treatments with diquat could control flowering rush populations from the shoreline to four feet water depth. We treated nine plots with diquat, and had four untreated reference plots. Sampling of flowering rush abundance indicated that this herbicide use pattern reduced aboveground growth 99%, and also reduced rhizome buds by 83%. In addition, the effect on native submersed plant species was much less than expected. Most native plants were unaffected by two treatments during the growing season.
Technical Abstract: Flowering rush (Butomus umbellatus) is an invasive aquatic plant introduced to North America from Eurasia in 1897. Flowering rush can grow either submersed or emergent from wet soil habitats to waters that are up to 5 m deep. Flowering rush was first observed in the Detroit Lake system in the 1960’s, causing significant impact of shoreline and recreational use. Flowering rush is currently found in five basins of the Detroit Lake system: Big Detroit, Little Detroit, Curfman, Sallie, and Melissa Lakes. Submersed treatments with diquat were used on an operational scale to control the nuisance impacts of flowering rush in waters from 0 to 1.3 m deep. We evaluated the response of native plant communities using a point intercept method on 30 or more pre-determined points per treatment plot, with three untreated reference plots. Treatment plots were sampled before treatment (June), and four weeks after each of the two treatments. We also sampled twenty biomass cores (0.018 m2) in each of four treatment and four untreated reference plots. While some species declined after treatment, species diversity did not change significantly after treatments. Treatments with diquat not only significantly reduce flowering rush distribution (60%) and aboveground biomass (99%), but also significantly reduced belowground biomass (82%) and rhizome bud density (83%). As flowering rush is an herbaceous perennial that propagates predominantly by rhizome buds, reductions in rhizome bud density indicate that this approach can be used for long-term reduction in flowering rush populations.