State finds new invasive weed

The state has identified a new invasive species poised to kick out the natives.

According to a news release from the Michigan Department of Natural Resources, Japanese stiltgrass has been positively identified on private property in Scio Township, near Ann Arbor in Washtenaw County.

“This annual grass is considered highly invasive, taking hold in areas of disturbed soil along banks, roadways and woods,” said Greg Norwood, invasive species coordinator for the DNR’s Wildlife Division. “Seeds can be transported by water or on animals, and seeds can remain viable in the soil for three to five years. Because deer don’t feed on Japanese stiltgrass, it often takes over in areas where deer browse on native plants and leave open patches of soil.” 

The identification of Japanese stiltgrass was confirmed by the University of Michigan Herbarium, It is the first detection of the species in the state.

The plant has been on the state's invasive species watch list since 2015 because it has been found in Ohio, Illinois and Indiana.

Researchers believe it came to the United States from Asia in the early 20th century as packing material for china pottery. It is established along the East Coast and in the South.

While Japanese stiltweed has not been identified in the Thumb, another native of Asia is causing problems in St. Clair County.

Japanese knotweed is a problem, said Kirsten Lyons, stewardship director for the Friends of the St. Clair River.

"We’re very concerned about Japanese knotweed," she said. "It’s one we do have and it’s very difficult to control."

The weed is thick on the hillside near the Blue Water River Walk, she said.

"It’s on the hillsides and in the wetlands. That’s one we’re having a contractor professionally treat.

"It’s been ongoing," Lyons said. "It’s being treated for a couple years now. It probably will always need some level of management."

Two other weeds are on the invasive species watch list for St. Clair County, Lyons said: European frogbit and flowering rush.

"We do have those," she said. "Both of those are in the delta, but they are small problems. We’re hoping the DNR gets hold of those before they get to be too widespread."

She said the state and volunteers also are watching for a weed called black swallow wort.

The DNR is collaborating with The Stewardship Network, a nonprofit conservation group based in Ann Arbor, and other partners to identify the extent of the stiltgrass infestation. To date, small satellite populations have been located on the original property and a nearby site. The primary infestation was treated with herbicide, and plant material was burned. The small patches of grass at the satellite locations were removed by hand and disposed of.    

How can you help?

The DNR is asking landowners, land managers and anyone spending time in the outdoors to watch for Japanese stiltgrass and to report the location and photos of any suspected findings to Greg Norwood at norwoodg@michigan.gov. 

Japanese stiltgrass looks like some native grasses, so it may not appear out of the ordinary to the general observer. Here is what to look for: 

• A thin, bamboo-like grass with jointed stems and well-spaced leaves.
• Smooth green leaves 2 to 3 inches long and one-half inch wide, tapering to points at both ends, often with an off-center silver stripe or mid-rib.
• 1- to 3-foot-high beds of grass, with some stems running across the ground and others shooting upright.
• Roots, both at the base and stem joints, that are weakly attached to the soil and easy to pull up.
• One to three slender, green flower spikes at the stem tips, appearing in August or September.

More information about invasive species, including identification information for Japanese stiltgrass, can be found at www.michigan.gov/invasivespecies.

The Midwest Invasive Species Information Network has information about plant, animal and insect invaders. Go to https://www.misin.msu.edu/

Contact Bob Gross at (810) 989-6263 or rgross@gannett.com Follow him on Twitter @RobertGross477.