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Fighting those frustrating beach weeds

Detroit Lakes,Minnesota 56501 http://www.dl-online.com/sites/all/themes/dlonline_theme/images/social_default_image.png
Detroit Lakes Online
Fighting those frustrating beach weeds
Detroit Lakes Minnesota 511 Washington Avenue 56501

Yes, some of the swimming areas along the Detroit Lakes City beach are weedy, but there's a method to the madness of the Pelican River Watershed District, which is responsible for weed control.

The district has hatched a long-term strategy to combat the main culprit -- flowering rush, a perennial aquatic plant that is on the DNR's prohibited exotic species list.

It grows like, well, a weed, and has proven very difficult to eradicate. For years, the watershed district has cut it down, but that has not been successful -- it's more plentiful than ever on lakes Detroit, Melissa and Sallie, according to watershed administrator Tera Guetter.

Now the watershed district is using the chemical Habitat (imazapyr) to attack flowering rush. But it has to be applied to the part of the plant that is above water, so that means no cutting.

That also means people should avoid boating through all areas of immerged vegetation: Damaged, cut or submerged plants will not absorb the chemical well, according to Ginny Imholte, who sits on the watershed district board.

The herbicide needs a no-use drying time of 24 hours. That means no swimming, boating or wave action, which can wash the chemical off the plant, preventing it from drawing the herbicide down into its roots, which will kill it in about three weeks.

For the same reason, no irrigation or lake water pumping is recommended for 48 hours.

With the blessing of the DNR, the watershed district started experimenting with using Habitat last year, when it was first approved for use against flowering rush, Guetter said.

It was applied in limited areas in the Deadshot Bay area. Pleased with the results, the district last year applied the chemical in a strip along the city beach from the Pavilion to Rossman Avenue. A wide strip of water off the city beach is now free of the nuisance weed, Guetter said.

But the lake level has dropped half a foot or so since then, exposing flowering rush further out along the beach.

Those weeds have also been treated with Habitat.

"We did a treatment last week before all the boat traffic hit," Guetter said Monday.

There are no recreational restrictions on boating or swimming that go along with the herbicide, but the beach was posted with "no swimming" signs as a precaution. The city also, for 48 hours, quit using its beachfront sprinkling system, which draws water from the lake, according to city street and park superintendent Roy Estes Jr.

"It's better to err on the side of caution, I think," Estes said. "That way people know what's going on."

More treatments will start Monday, weather permitting, and continue for about a month, Guetter said.

"We need extremely calm weather conditions," she said. "We'll be conducting treatment extremely early in the morning or in the late evening hours."

The Pelican River Watershed District will spray flowering rush from Monday through Aug. 11 on Big Detroit, Little Detroit, Deadshot Bay, Lake Sallie and Lake Melissa, Imholte said.

Lakeshore owners should watch their neighborhood waters for markers or their docks for a dated orange notice.

Information sheets will be placed at the boat accesses in the Lake Detroiter pamphlet boxes and at the gas pumps of Long Bridge and the J & K Marina dock.

The Pelican River Watershed District website -- prwd.org -- has additional information.

Imholte said the treatment will take several weeks to be completed, though the flowering rush may start to show signs of spray damage after a week, then die down in August.

The new young plants will be treated next year as they mature above the water, she added.

The problem weed is very difficult to identify when not in flower, since it closely resembles many native shoreland plants -- including the common bulrush, which are desirable and are protected, Guetter said.

Flowering rush grows 1- to 4-feet high on an erect stem along shores, in shallow water. In deeper water it grows submerged, without producing flowers.

Its leaves are sword-shaped, triangular in cross section, and it has pink flowers arranged in an umbrella shape, according to the DNR.

Flowering rush is a Eurasian plant, sold commercially for use in garden pools. It is now illegal to buy, sell or possess the plant, which can drive out native shoreland vegetation.

Detroit Lakes City Council member James Hannon said he heard from several people over the Independence Day weekend that were concerned about weeds on the city beach.

"They said it didn't appear anything was being done about it," he added.

That's not the case, and people should know about the weed eradication effort, he said, adding that the city supports the watershed's program.

Estes agreed. Although the weed will probably always be around, if all goes well the watershed will likely be able to reduce its efforts to simple spot treatments in a few years, he said.

"It's a good program, based on the meetings I've been at (with the watershed district and the Lake Detroiters Association)," Estes said. "It's a treatment program that requires patience."

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