Valerian spreading, challenging landowners

posted Aug. 20, 2018 11:24 a.m. (CDT)
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by / Heidi Clausen, Editor |

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    An Asian plant that was brought to Europe and then the U.S. for medic­i­nal and gar­den use, va­le­rian is known for its height and dis­tinc­tive um­bels of white to pink trum­pet-shaped flow­ers.
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    A fenceline dividing two properties near Poplar in northern Wisconsin illustrates the drastic difference between open pasture and an uncut area in which garden valerian weed has taken hold. “You can see how the valerian weed totally took over and came out of nowhere to invade. The weeds in that stripe have now gone to seed. They are 6 feet tall and have a terrible smell,” Jerry Kroll said.

To say that invasive garden valerian has overstayed its welcome in Wisconsin might be an understatement.

Beef producer Jerry Kroll has been battling the hardy, pungent weed throughout this summer. Most worrisome to him is that it’s potentially poisonous to his cattle.

“I’m totally surrounded by it,” said Kroll, who winters about 135 head of Red Angus beef cattle at his Kingbird Ranch near Poplar, which includes more than 300 owned acres and an additional 140 acres of leased hay ground. “This menace needs to be exposed.”

Douglas County’s town of Amnicon has been ground zero for the unwelcome invader, which has been spreading through northern Wisconsin ditches and fields since it was first documented in 2001. It also has been heading south and been spotted elsewhere in the state.

The number of sightings of the invasive weed in Wisconsin jumped from about 50 in 2007 to more than 250 the next year. That number has since climbed to almost 400, with most reports in northern Wisconsin, according to Mark Renz, UW-Extension weed specialist.

An Asian plant that was brought to Europe and then the U.S. for medicinal and garden use, valerian is known for its height and distinctive umbels of white to pink trumpet-shaped flowers. Standing about 6 feet tall, it typically towers above its vegetative neighbors, forming a canopy over them and choking them out, and discouraging new vegetation. The plant favors cool, wet, open areas, and its early emergence, vigorous growth and ability to self-seed give it an upper hand.

“It has been cultivated for hundreds of years in Europe for supposed sleep aid and as a horticultural garden flower,” said Jane Anklam, Douglas County UW-Extension agriculture and horticulture educator. “It moved into the Twin Ports within the last 15 years and is starting to spread across the north and south.”

Garden valerian is spread through root nodes and seeds. Kroll said it travels through the air and typically pops up in areas that haven’t been cut routinely.

It also spreads via round bales transported from other regions where valerian exists.  With the growing number of small cow/​calf operations in northern Wisconsin, more hay is being trucked into the area. Kroll said Douglas County has more beef herds with fewer than 20 cows than anywhere else in the state. There’s also speculation that it may have arrived here on ships from nearby Lake Superior.

The weed poses an economic threat to farmers as it lowers the quality of hay and pasture, but it also can alter local water quality, plant diversity and native habitat. It invades upland forests, wetlands, marshes, woodland swamps, grasslands and stream edges.

Kroll said valerian has really taken off in areas not well managed by farmers and other rural landowners. With the recent hot, dry conditions and soft hay market, some farmers haven’t been cutting fields this year. He’s concerned that, as the hay market picks up, valerian could spread as the seed is raked up, baled and hauled elsewhere.

“Our big dilemma now is valerian weed that has pretty much taken over,” he said. “It has really taken hold and gone crazy. We don’t have a good handle on it.”

Kroll said the weed is minimized in his fields that are cut and grazed regularly, so he tries to keep fields and ditches trimmed so it doesn’t get established. He also has pulled cattle off some of his rotationally grazed pastures and is supplementing their diets with hay so he can at least get some fall grazing in.

“More and more people are clipping their fields down now,” he said. “It’s a little late, but they have come to the fact that this isn’t something you want spreading.”

While there is no recommended management for valerian at this time, UW-Extension specialists are testing eight herbicides on a field of valerian in Amnicon township. Results gleaned from the site will help provide advice for the entire state.

“The trials are designed to help UW-Extension develop information to guide landowners and municipalities on the most appropriate ways to manage the weed outbreak, including herbicides,” Anklam said.

Kroll said some of these tests show promise because, while the weed is still present, it doesn’t seem to be as thick.

“I’m not sure what we’ll do if herbicides don’t take care of it,” he said.

In the meantime, Kroll urges farmers and other landowners to be on the lookout for valerian weed and start clipping in an effort to manage its spread.

“Hay buyers, beware of hay coming out of Douglas County,” he said. “It should be red-flagged. We can’t let it escape.”

Along with battling valerian weed, Kroll said cattle producers in his area have their hands full with the growing wolf population. Douglas County is home to almost 30 wolf packs, and they’re especially active this time of year as older wolves are teaching their offspring to hunt, he said.

Those who find garden valerian are asked to report it by emailing the Wisconsin First Detector Network at or calling their local UW-Extension office.

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