Japanese Stiltgrass

Stiltgrass

Microstegium vimineum

2019 Status in fb88: Localized. Severely Invasive.

Description: Herbaceous, annual grass, 1-3' tall, with a branching habitat. Plant resembles a small, delicate bamboo. Leaves: Alternate, pale green, ½" wide and 2-4" long with a stripe of reflective hairs on the midrib of the upper leaf surface. Flowers/Seeds: Flower heads develop late in the season (September) and contain 1-3 flower spikes, resembling crabgrass. Each plant can shed hundreds of yellow-reddish ellipticalseeds before dying in late fall.

Native range: Southeast Asia. How arrived in U.S.: In packing grass for Asian porcelain.

Reproduction: Produces new plants only by seed, which is viable 3-5 years. New shoots can grow from stem nodes during growing season.

Similar native species: Grasses can be difficult to identify without training. There are a number of species with either similarly shaped leaves or similarly shaped inflorescences as Japanese stiltgrass, but not both. Virginia cutgrass, also known as whitegrass (Leersia virginica), has both similar leaves and a similar inflorescence. However, Virginia cutgrass has a hairy ring around the stem nodes (vs. none on Japanese stiltgrass), and it lacks the shiny hairs on the leaf midrib.

Similar non-native species: As with the native grasses, there are likely some species of non-native grasses with either leaves or inflorescences that look like Japanese stiltgrass.

Documented Ecological Impacts

• Japanese stiltgrass has potential to significantly alter soil chemistry. A greenhouse experiment showed a rapid rise in soil pH and available phosphorus, which may reduce diversity in soil and litter microarthropods. ()
• Japanese stiltgrass may accelerate carbon cycling and deplete below-ground carbon pools in forests. ()
• Japanese stiltgrass can strongly reduce native tree seedling regeneration and size, which may slow the rate of forest succession and alter tree species composition. ()
• Soil microbial communities in a hardwood forest invaded by Japanese stiltgrass were significantly different than in a non-invaded forest. ()
• Japanese stiltgrass has the potential to invade rare floodplain forests in fb88. Since these are rare habitats, invasions there are of top concern for conservation of biodiversity.

Fact Sheets and Identification Links

• Go Botany page for

Control Methods

Plants are shallow rooted and easy to hand pull if the patches are small^*. Mowing before seed set is effective (before August). Grass-specific herbicides^† (clethodim, quizalofop, P-ethyl, sethoxydim) are very effective. Folar applications of glyphosate are effective. Imazapic is also effective in combination with glyphosate, but this should be used only via consultation with a licensed applicator due to the residual soil activity of this type of herbicide. Special rules apply to herbicide use in or near wetlands and water bodies - consult the fb88 Board of Pesticides Control..

^{* Correctly dispose of all plant parts↵ † Follow all label directions when using herbicides↵}

Control Technique Links

Please email invasives.mnap@maine.gov if you have questions about invasive species in fb88