Starry stonewort is arguably the most aggressive aquatic invasive plant-like organism in the United States. It spread quickly in Michigan from just one infested lake in 2006 to two hundred infested lakes by 2012.
The discovery of starry stonewort in Lake Koronis in Stearns County in August 2015 was followed in August 2016 by an almost weekly DNR announcements of additional lakes infected with starry stonewort.
Now, infected lakes in the Bemidji area infected are: Turtle, Upper Red Lake, Cass Lake, Moose, and Winnibigoshish. In Stearns county, add Rice Lake, Mud Lake, and West Lake Sylvia.
It looks like a plant with long stems which tangle up to form dense, tangled underwater masses. It is really an algae–a precursor to primitive plants.
Despite Michigan’s extensive experience with it, researchers still have not discovered a way to effectively control it. Chemicals kill part of the plant, but it grows back a few weeks later.
The DNR is attempting to remove it in Turtle Lake using suction machines in the infected area followed by a copper-based plant poison.
It is very thick and dense; an incredible 140,000 lbs of starry stonewort was removed from Lake Koronis using mechanical harvesting of just 6 acres. It was reported in 2015 that at least 250 acres are affected in that lake.
Total removal has never been accomplished, so far, in the United States.