Last year our company took on the largest aquatic plant management program ever undertaken in the Pacific Northwest when we targeted over 4,000 acres of Eurasian Milfoil on Pend Oreille Lake and River. This program was funded by the Idaho Department of Agriculture. The primary herbicide used was Sonar PR, a controlled release granular formulation.
At the end of last summer, the results of this project were not yet clear, Sonar is a very slow acting product. We were however confidant that it would be successful.
In June of this year, the state of Idaho contracted with Dr. John Maden of Mississippi State University to study the results and quantify them. His results as reported to the Bonner County Milfoil Task Force were as follows: “the control achieved in all areas is rated from very good to excellent”; and with a rating of 1 for topped out milfoil, 2 for milfoil observed in the water column, 3 for milfoil not visible but collected on a rake sampling system and 4, milfoil not present, Dr. Madsen indicated that of the 1,800 sampling points in last years treatment areas, the average rating was 3.96 on this scale.
This video clip shows last years application. http://www.spokanetogo.com/news-video/?id=1678