Invasive stiltgrass cropping up around southern Michigan

In early August, Simic located the stiltgrass infestation at Petersburg State Game Area in Monroe County by following up on an online report submitted by a park user, who had begun removing the grass. The response team manually removed and disposed of all visible stiltgrass and will continue to monitor the site and remove new growth.

Bekins detected stiltgrass at the Barry State Game Area in Barry County while conducting an oak wilt survey in late August. Just a few weeks later, she encountered the invasive grass at Augusta Creek State Game Area in Kalamazoo County. Chemical treatment and manual removal were used at both sites. The response team will work with game area staff to continue monitoring and expand survey efforts along roads and rights-of-way in both areas.

Other Michigan infestations

Invasive stiltgrass is widespread in the southeastern U.S., including expanding areas in Indiana and Ohio. It was first detected in Michigan in 2017, when an infestation was confirmed on private lands in Washtenaw County.

Additional surveying has shown that this original infestation covers a large area of both public and private land along the Huron River northwest of Ann Arbor. A coalition including Ann Arbor and Washtenaw County parks and recreation departments and Wild Ones, a native plant collaborative, is managing infestations on public lands and training landowners in techniques for private land management. The Jackson, Lenawee and Washtenaw Cooperative Invasive Species Management Area continues to scout for new infestations in the area.

Smaller infestations in Berrien, Cass and Kent counties are being managed by local CISMAs.

Why be concerned?

Invasive stiltgrass (Microstegium vimineum) – also known as Nepalese browntop or Japanese stiltgrass – is highly adaptable, thriving in various soil, moisture and light conditions. It takes hold in areas of disturbed soil along forest edges, roadways, recreational trails, floodplains and stream corridors.

Each plant can produce up to 1,000 seeds, which can be spread by vehicles, foot traffic, water and wildlife. Because deer don’t feed on stiltgrass, it often takes over in areas where deer browse on native plants and leave open patches of soil.

You can help

Landowners, land managers and anyone spending time outdoors should look out for stiltgrass and report the location and photos of any suspected plants to the Midwest Invasive Species Information Network.

Identify stiltgrass

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.

Be aware of look-alikes

A few common plants in Michigan easily may be mistaken for stiltgrass.

• Smartweeds (Polygonum spp.), with tiny, white to pink flowers on a short spike and a tell-tale dark blotch near the center of each leaf. 
• Whitegrass (Leersia virginica), which is well-rooted in the soil and has longer, thinner leaves than stiltgrass, with no mid-rib stripe. 
• Northern shorthusk (Brachyelytrum aristosum), with fine hairs on the top, bottom and edges of its leaves and stems, and leaf veins in a pattern resembling an irregular brick wall.    

Prevent the spread  

When enjoying the outdoors, stay on trails and, whenever possible, park in paved or cleared areas. If you have been hiking, biking or four-wheeling, always take time to clean your shoes, gear and vehicles before going to a new location.

More information on invasive species identification and prevention is available at Michigan.gov/Invasives.

Michigan's Invasive Species Program is cooperatively implemented by the Department of Environment, Great Lakes, and Energy; the Department of Natural Resources; and the Department of Agriculture and Rural Development.