Japanese stiltgrass, an invasive grass not native to Wisconsin, has been spotted in a private woodland near Beloit in Rock County, the Gazette Xtra reported. Experts warn the presence of this sprawling grass could carry serious consequences for the region’s native ecosystems.
What’s happening?
In August 2025, the University of Wisconsin–Madison Extension specialists and Wisconsin DNR discovered a significant infestation of Japanese stiltgrass in a Beloit woodland, marking only the second recorded sighting in the state. The first instance, reported by the same publication, was in La Crosse County back in 2020.
Mark Renz, a UW–Madison Extension weed specialist, called the grass “quite harmful to our forests,” noting it intensifies wildfire risk, disrupts soil nutrient cycling and microbial communities, and suppresses wildlife habitat, collectively reducing biodiversity, according to the Gazette Xtra.
Initial surveys have not located additional infestations nearby, but officials warn that it likely went undetected for years, possibly introduced via contaminated equipment or soil from infested areas to Wisconsin’s south.
Why is the appearance of this grass important?
Japanese stiltgrass readily forms dense mats that overrun native plants in forests, along stream banks, and in lawns, choking out early and late-season species, and even attracting other invasive species.
Its prolific seed production — hundreds to thousands per plant — creates persistent seed banks that can germinate for years. The grass’s invasion disrupts soil conditions; hinders tree seedling growth; suppresses native plant, insect, and wildlife communities; and further compromises restoration efforts.
Outcompeting native species erodes the resilience of local ecosystems, undermining natural communities and delaying progress toward a healthier environment and safer future for communities.
What’s being done about the stiltgrass?
Stopping stiltgrass before it spreads further will take persistence. Experts say small patches can often be pulled by hand, especially if they’re removed before the plant drops its seeds. Mowing late in the summer can also help keep it in check.
The challenge is that its seeds remain viable in the soil for years, which means landowners may need to return to the same spot season after season to make sure it doesn’t come back.
Local officials are also asking residents in southern Wisconsin to be part of the effort by watching for the grass in yards, woods, and along trails. If it’s found, taking photos and reporting the location to UW–Madison Extension or the Department of Natural Resources gives land managers a chance to act quickly.
Restoring cleared patches with native groundcovers is another important step. Plants like Virginia cutgrass or jewelweed can fill the empty space, making it harder for stiltgrass to return.
Together, these small but steady actions give communities a chance to protect local woodlands, reduce fire risk, and preserve the resources people and wildlife depend on.
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