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Putting the bite on flowering rush

Patrick Selter with PLM Lake and Land Management applies the herbicide diquat to an area on Big Detroit Lake where flowering rush has been growing like wildfire. Experts and homeowners alike say the treatments have been tremendously successful this year. Photo by Paula Quam/DL-Online

During a time when invasive species news has been less than encouraging, finally a bright spot.

Officials working on eradicating flowering rush around area lakes say they just may finally have the weapon they need .... an herbicide called diquat.

The product has been around for 30 years, but experts just stumbled upon its effectiveness on flowering rush four years ago when they were treating a private residence on Curfman Lake.

"It was in and amongst other products being used because they had a variety of weeds, but when we came back we saw the flowering rush was gone," said Patrick Selter with PLM Lake and Land Management -- the company contracted to carry out the research applications.

He says from there, researchers began to study the herbicide and its effects on flowering rush.

It took one year in the lab and one year of testing it out on very small plots last year.

The results were astounding, leading them to this year's large-scale experiment.

The first round of diquat was applied about a month ago.

"I saw them spraying and thought, well, OK ... it's good they're giving it another shot anyway," said Ed Van Hall, who owns a cabin on Big Detroit. He said the flowering rush was so thick he didn't even know if he was going to be able to get his boat in. But two weeks later, his wife asked him if he noticed anything.

"I looked out and there were no more weeds," said Van Hall, "it was the first time after all these years I saw a real result ... I was so pleased."

The Pelican River Watershed District contracted PLM to apply the herbicide (diquat for the plants below the water and emazapure for those popping above) to experimental plots around Big and Little Detroit and Lakes Melissa, Sallie, and Curfman.

The project is under the direction of Geosystems Research Institute of Mississippi State University, Concordia College and the U.S. Corps of Engineers.

Representatives from these organizations have been working together to find the most effective way to eliminate the invasive species plant from area lakes.

This year, the large-scale diquat project has flowering rush dying off like crazy, leaving local lake lovers excited.

"It's boosted our confidence a bit because we've been working on this since 1990," said Dick Hecock, senior advisor at the Pelican River Watershed District and president of the COLA.

"We've been seriously trying to figure out what do with this flowering rush, and it's not been a pretty picture. But now, we're hearing from boaters, swimmers, fishermen and homeowners that the treatment from last month was extraordinarily successful."

Now, a second round of the same herbicides are being applied, as nearly 300 gallons of the chemical are being applied to roughly 200 acres within the chain of lakes.

Selter says the diquat seems to work both for emergent and submergent plants, and because of this, they will likely just use this herbicide in the battle next year.

And there will be a next year.

The chemical has one flaw -- it doesn't seem to kill the root.

"So what they're doing now is a follow up treatment ... part of a long term strategy that will involve multiple years," said Hecock. "Our hope is that as we treat it, it will exhaust itself."

During this time, research will also continue on possible side effects of the herbicide, including how it affects other lake species.

"The concern is that with any chemical that can kill something, we need to find out what else it kills, especially when it's a broad herbicide," said Barry Stratton, Southern District manager for the Minnesota DNR.

Stratton says much research will now be conducted from these plots to determine any intentional and unintentional effects.

He says after seeing the plots for himself, he believes the short-term results are "amazing," but he says, there is still research to be done to get "to the root" of the problem and eliminate flowering rush in the long-term.

"But this treatment is a great example of the community, the watershed district and the DNR working together -- especially the work that the Watershed District has done," said Stratton. "It's ground breaking research they're taking the lead on in the country, so it's very, very impressive."

The cost of this year's two treatments will cost an estimated $90,000, which is being split up between the Watershed District, the city and the state.

City residents earlier passed a special sales tax to help pay for the research.