Flowering Rush Seed Removal

August 31, 2017 Dear Friends of the Lake; Forest Lake is home to an invasive emergent plant called flowering rush that is spread via seed dispersal and rhizome (root) fragmentation. The control of flowering rush has been ongoing for 3 years.  The Comfort Lake-Forest Lake Watershed District (CLFLWD) manages flowering rush through herbicide treatments and manual flower cuttings. The purpose of the flower cutting is to remove flowers from the flowering rush plants before they can deposit seeds into Forest Lake.  In 2016, CLFLWD staff determined that the flowers on a single stem of flowering rush may produce up to 14,000 seeds annually.  Each of these seeds has the potential to start a new patch of flowering rush in Forest Lake or start an infestation of flowering rush in a new lake. On August 14th, 2017 the CLFLWD hired PLM Lake and Land Management to treat 40.2 acres of flowering rush in Forest Lake using the herbicide Diquat. The herbicide treatment occurred in similar areas of 2nd and 3rd lakes as those that were treated with herbicide in 2016. A second herbicide treatment will occur in late August or early September. On August 24th Jerry Grundtner with the FLLA and Mike Sorensen with the CLFLWSD collected flowers and seeds on August 24th, 2017. The entire shoreline of 2nd Lake and 3rd Lake was inspected by boat. When flowering rush flowers were observed, the flowers were carefully cut with a pair of household scissors and placed in a garbage bag inside of a plastic tub. We believe that we were able to remove 99% of the flowers but there may be some isolated flower heads still on the lake and there is still the potential for new flowers. In all, exactly 800 stems with flowers were collected. This can be compared to 276 stems with flowers that were collected last year. Since each stem may produce up to 14,000 seeds annually, collecting 800 stems may keep up to 11,000,000 seeds out of Forest Lake. With regard to disposal, all flowers and seeds have been transported in sealed containers to a location away from public waterbodies where they were burned. A second round of flower collecting will be performed in coming weeks prior to the second herbicide treatment. We ask that you do not cut any flowers if you see them as incorrectly cutting them will spread flowering rush even more. Figure 1. A sample of the 800 flowers that were collected on August 24th, 2017. Some of the flowers were still green with undeveloped seeds, while others were dry and easily dropped their seeds when touched.