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Hunt is on statewide for wetland invader

Purple loosestrife is pushing out native plants

Milwaukee Journal Sentinel staff

State residents are searching more than a dozen counties this month for infestations of an aggressive European invader - purple loosestrife - that is shoving aside native wetland plants and the animals that depend on them in a steady march across Wisconsin.

In canoes, boats and cars, on foot and bicycles, about 150 volunteers for the Wisconsin Wetlands Association are noting the locations of the tall, magenta spires of loosestrife in Milwaukee, Ozaukee, Racine and other counties along the shores of Lakes Michigan and Superior.

Information gathered by this surveillance squad will help the association and other groups target future loosestrife control efforts in those counties, said Derek Strohl, the association's program director.

"We hope to take the survey statewide next year because that has not been done in 15 years," Strohl said. The search is funded by grants from the Wisconsin Coastal Management Program and the American Transmission Co., whose employees frequently encounter the weed.

Since the last statewide census of this exotic nuisance was done in 1987, purple loosestrife has spread across Wisconsin and is now found in marshes, wet meadows, lake shorelines and roadside ditches in each county, said Brock Woods, an aquatic ecologist and coordinator of the University of Wisconsin Extension's purple loosestrife biological control program.

At least 40,000 acres of wetlands have been overrun by this seemingly indestructible plant.

"The La Crosse River is choked with loosestrife," Woods said. "New London is the color purple along the Wolf River, and the Wisconsin River at Stevens Point is purple." So, too, is the City of Superior.

Wherever loosestrife goes, most other life departs.

"We lose the diversity of plant and animal life in our wetlands," Woods said. "You won't find our native insects in loosestrife, so birds and spiders that prey on the insects also leave. As loosestrife knocks out cattails, it also knocks out muskrats that depend on them. And the dense stands of loosestrife also eliminate fish spawning habitat."

Purple loosestrife gains the upper hand in competition with native plants for two reasons: its height and its uncommon ability to produce seeds.

"This loosestrife out-competes any other wetland plant, including cattails, sedges and bulrushes," Woods said. "It can get to be 8 to 9 feet tall and shades out the other plants."

A single stalk produces 100,000 seeds or more each year, and mature plants grow as many as 50 shoots. As loosestrife matures, it forms dense root clumps that push aside everything else.

This alien was first found growing wild in Wisconsin in the early 1930s but did not gain a foothold in wetlands of major rivers and their tributaries until the 1970s.

Beginning in the 1800s, purple loosestrife was imported from Europe and sold as a showy garden perennial. Horticulturists promoted its attractive blooms. Then it began to spread from gardens to wetlands.

Today, it is illegal to distribute the plant in Wisconsin and 23 other states.

The absence of natural predators on this continent allowed purple loosestrife to advance across the United States, according to Woods.

Subsequently, researchers turned to its homeland to find something that would slow its growth.

Galerucella beetles were imported from Europe in the early 1990s for only one purpose: eating purple loosestrife leaves. They do not eat our native wetland plants, and it is a lot easier for citizens to release beetles than it is to pull or cut loosestrife, Woods said.

Since 1997, the state Department of Natural Resources has distributed beetles to conservation clubs, lake associations, schools, Boy Scout groups and farmers. More than 300 groups and individuals have reared large colonies, eventually releasing several million beetles in the last five years to combat the loosestrife invasion.

"Evidence of beetle success is stunning in places, such as Henrietta Lake in Waukesha County, while other areas have been slower to show changes," Woods said. "The bad news is that there is still a lot of loosestrife out there without beetles."

To fill the gaps, the University of Wisconsin Cooperative Extension Service will schedule several workshops this fall to train more citizens in the rearing and release of the beetles.

Jay Sadlon, a member of the Buttes des Morts Conservation Club, has helped release about 200,000 beetles since 1999.

These little predators wiped out about 80% of the loosestrife in one wetland near the mouth of the Fox River in Lake Butte des Morts where the club is attempting to restore wild rice and bring back ducks and other wildlife, Sadlon said.

"The beetles don't get rid of it, but they do control it," he said.

Loosestrife, however, still dominates 300 to 400 acres of wetlands in the lake, according to Sadlon.

The Lake Poygan Sportsmen's Club released a few hundred thousand beetles late last month in a wetland on the north shore of that lake, said Gordon Alfter, a club member.

Millions more will be needed to chew up all the loosestrife on the shores of Lake Poygan, according to Alfter.

"There's miles and miles of marsh here that we've already lost to purple loosestrife," he said.

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