In 2010, the District gathered experts from around the US to form a collaborative effort to research the growth cycle, habitat, and herbicide options to better understand Flowering Rush and develop better management strategies. The partnership included the Pelican River Watershed District, Mississippi State University Geosystems Research Institute (GRI), Concordia College (Moorhead, MN), US Army Corps of Engineer Research and Developments Center (USACERDC), and the Minnesota Department of Natural Resources-Ecological and Water Resources Division.
In order to most effectively reduce Flowering rush populations, submersed (below water surface) Flowering rush was targeted for the treatment research project. The growth cyle and habitate studies were used to refine herbicide application timing and water depths for treatments. Small-scale herbicide trials and an in-lake dissipation study were conducted in 2010-11. Based upon these promising results, in 2012, the first operational-scale of Flowering rush in-lake treatments were conducted on Detroit, Curfman, Sallie and Melissa lakes. In 2013, the treatment areas were expanded due to the significant reduction of below surface plants and roots following treatment with limited impact on native plant species. In 2015, the District began adapt the management plan to reduce the frequency of treatment for low density areas. Currently the District treats populations annually with the adaptive management plan.
ECOLOGY AND PHENOLOBY OF FLOWERING RUSH
LAKE-WIDE HERBICIDE TREATMENTS
DEVELOPING AN ADAPTIVE MGMT PLAN FOR FLOWERING RUSH
In 2015, the District began a 2-year pilot study to treat mixed stands of Flowering rush and native hardstem Bulrush on the east side of Lake Sallie. Flowering rush was invading and displacing a 60-acre area of critical hardstem bulrush habitat. The study involved a small 5-acre test plot and concluded treatments had no damaging effects on the native Bulrush and significantly reduced Flowering rush populations. Other native plant species such as the Pond Lily reestablished in the treated areas. The treatment areas were expanded to 23 acres and in 2017 and the entire mixed stand areas (approximately 60 acres) were treated in 2018.