AmeriCorps plays central role in controlling noxious weeds

Zach Dieterman, the South District field coordinator for the Rochester-based AmeriCorps crew in August 2018, walked into an area where a Conservation Corps Minnesota & Iowa crew working through the Fillmore SWCD had treated the banks of the Root River at a public access with herbicide. In 2017, funding from state partners allowed for treating about one-third of known Japanese hops locations and all known poison hemlock locations along the Root River. Dieterman has since taken a job with the Minnesota DNR. (Photo by Ann Wessel, BWSR)

PRESTON — The Fillmore Soil & Water Conservation District is battling two non-native weeds that threaten the Root River. Japanese hops and poison hemlock, both on Minnesota’s Noxious Weeds List, choke out native species that shade streams and stabilize their banks — putting cold-and-clear-water trout habitat at risk.

For the fourth consecutive season, a Conservation Corps Minnesota & Iowa crew this summer located pockets of the weeds in Fillmore and Houston counties and treated them with herbicide. By mid-August, the two- to three-person crew had worked 456 of the 800 hours allotted.

Work is planned through late October.

The Minnesota Board of Water and Soil Resources’ annual appropriation of $500,000 in Clean Water Funds pays for AmeriCorps crews’ labor costs. Local government units submit applications for work projects, and often provide matching funds. For the past two years, crews have continued the Minnesota Department of Natural Resources and Department of Agriculture’s noxious weed control work in Fillmore County that dates to 2016.

As new infestations were discovered, the project’s scope grew.

The focus on Japanese hops — discovered during a 2015 river and trail survey — started in parking lots, canoe access points, along the Root River State Trail and within the strip of land between the trail and river. It’s since expanded to private land.

Native to Asia, Japanese hops are prolific annual vines. Growing up to 35 feet in one season, they can smother the diverse native vegetation that stabilizes riverbanks, filters runoff and provides wildlife habitat. Japanese hops are easily killed but easily spread.

“The hops will continue to be an ongoing battle just because of the severity of the infestation along the Root River,” said Zach Dieterman. The South District field coordinator for the Rochester-based CCMI crew in August 2018, Dieterman has since taken a job with the DNR. “The Root River is such a desirable and well-used recreational route for kayakers and tubers and people who are using the bike trail. It’s something that we want to keep as a nice natural resource for recreation purposes.”

When Japanese hops die off and go dormant, Dieterman explained during the August 2018 tour of a treated site, they leave bare, erosion-prone riverbanks.

“We’re trying to get it back or maintain the kind of plant biodiversity that makes the Root River and the area unique,” Dieterman said.

Treatment in 2016 seemed to control the populations. Off-river and trailside work showed positive results, but high water in 2017 made riverside treatment too dangerous. This spring’s high water and flooding likely moved weed seeds farther downriver.

In an Aug. 8 news release, the Minnesota Department of Agriculture solicited help from the public in reporting new finds and controlling Japanese hops. Infestations have been confirmed along the Root River from Preston to the confluence of the Mississippi River.

An MDA grant allowed Fillmore SWCD and Houston County Planning and Zoning to expand treatment this season, according to the MDA release.

The focus on poison hemlock, a biennial, centered on the Root River near Lanesboro.

Christina Basch, the Minnesota Department of Agriculture’s Rochester-based noxious weed eradication specialist, coordinates AmeriCorps crews’ work and surveys the sites.

“I am worried with these flooding events we’ll see more poison hemlock,” Basch said earlier this season.

As of mid-August, Basch said it appeared as if containment efforts were having an effect. Only a few new locations had been discovered. The MDA and DNR have seen a dent in poison hemlock populations where it has been treated.

During on-river treatment assessments of both weeds from Preston to Houston in mid-August, Basch said MDA and CCMI workers saw patchy but dense Japanese hops infestations. The effect of on-river treatments was noticeable, but large patches remained. Japanese hops didn’t appear in areas eroded by spring floods, but treatment was advised over the next few years. Treated poison hemlock sites showed no seed production. The crew observed two new poison hemlock sites.

Seeds of both invasive weeds are easily transported via animals, footwear or equipment. Partners have educated anglers and recreational trail users through posters and workshops.

“With hops, since it does create those dense mats, it can get almost like a snare where if people walk through it they can get trapped,” Basch said. Poison hemlock is highly toxic; ingesting a few leaves can kill an adult.

The SWCD, MDA and DNR are among those tackling invasive species in southeastern Minnesota before eradication becomes impossible or control becomes too expensive.

Additional partners have included the Minnesota Department of Transportation, University of Minnesota Extension, the U.S. Fish & Wildlife Service, Trout Unlimited, counties and county agricultural inspectors.

— Minnesota Board of Water and Soil Resources

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