On June 6, 2019 the herbicide ProcellaCOR (Florpyrauxifen-benzyl ) was utilized to reduce Myriophyllum spicatum (EWM) in two beds totaling 12.2 acres. The frequency of occurrence (FOO) had a significant reduction (p<0.0001 from chi square analysis) with an FOO of 59.5% within the treatment bed before treatment to 0% after treatment. There was one significant reduction in native species (Potamogeton pusillus) and three significant increases in native species (based upon chi square analysis before and after treatment).

In July and August 2018, DASH (Diver Assisted Suction Harvest) was employed to reduce/control stands of Myriophyllum spicatum-Eurasian watermilfoil (EWM) in Cedar Lake. The areas that were harvested were based upon pre-harvest surveys conducted in areas that have historically been managed in the past using herbicide. Due to the lack of success with herbicide (2,4-D and Diquat/Endothallwere used on different occasions with limited reduction), herbicide use was ceased for 2018.

An herbicide application of Aquastrike® (mixture of diquat and endothall) was conducted in a 2.6‐acre bed of EWM (Myriophyllum spicatum) on May 9, 2017 on Cedar Lake, St. Croix County Wisconsin. A post treatment survey on July 11 resulted in a frequency of occurrence (FOO) of EWM of 46.2% and a density of 0.64 (scale of 0‐3). This was a slight decrease from a September 2016 survey where the FOO was 48.7% and a mean density of 0.72. There was no statistically significant reduction in EWM based upon a chi‐square analysis. There was a significant reduction of five native species based upon a chi‐square analysis between 2016 and 2017 post treatment surveys. Hand pulling efforts using diver assisted suction harvest (DASH) removed approximately 5000 lbs. (wet weight) of EWM. Follow‐up hand pulling with divers removed an additional 200 lbs. There was a frequency reduction (51.4% to 24.3%) in EWM within the DASH sites based upon a chisquare analysis. The mean density was also reduced. A survey before and after DASH using a sample grid around all historical EWM control areas (treatment and diver removed) also showed a frequency reduction from 30.8% to 18.8%, but was not quite significant (p=0.06). A baseline EWM evaluation on a larger, long‐term sample grid was completed in September 2017 with a EWM FOO of 7.03%.

Grant AIRR22518 awarded