Japanese Stiltgrass

Fact SheetMicrostegium vimineum

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Common look-alikes:

Identification

Appearance

Microstegium vimineum is a delicate, sprawling, annual grass that is 0.5-3.5 feet in height. The stems can root at the nodes.

Foliage

The leaves are pale-green, alternate, lance-shaped, 1-3 inches long, asymmetrical with a shiny, off-center midrib. Upper and lower leaf surface is slightly pubescent. A silvery line runs down the center of the blade. Stems usually droop.

Flowers

Flowering begins in September, when delicate flower stalks develop in the axils of the leaves or at the top of the stems.

Fruit

Fruit is produced from late September through early October.

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Biology

Ecological Threat

When Japanese stilt grass invades a site, it can quickly crowd out native plant species. Invasions can also change soil nutrient cycling processes, inhibit tree survival and growth, and reduce light availability. After it dies back in late fall, it forms a thick layer of smothering thatch that is slow to decompose. Because stilt grass is relatively unpalatable, it may encourage heavier deer browsing on native plant species.

Origin

Japanese stilt grass was first documented in Tennessee in 1919. Its introduction into the United States was accidental, likely a result of its use as a packing material for porcelain.

Habitat

Forests, forest edges, floodplains, marshes, meadows, fields, riverbanks, lake shore, disturbed areas

Life Cycle

Stilt grass reproduces exclusively by seed. One plant may produce 100 to 1,000 seeds that typically fall close to the parent plant. Seeds may be carried by water during heavy rains or move about in contaminated hay, soil or mud stuck in footwear. Stilt grass seeds remain viable in the soil for five or more years and germinate readily.

Management Options

This is considered a watch list species

Mechanical Control

Hand pull: Stilt-grass is a weak rooted annual and small populations can be hand pulled any time during the growing season when the ground is soft. Be sure to pull up the entire root system. Pulling is easier and probably more effective in mid-to-late summer when the plants are much taller and more branched. Hand pulling of plants will need to repeated and continued for many seasons until the seed bank is exhausted.

Mowing: Larger infestations can be mowed or weed-whacked when plants are mature but seeds have not yet set. Because stilt- grass is an annual plant, cutting late in the season before the plants would die back naturally avoids the possibility of regrowth.

Chemical Control

Be careful not to damage or kill nearby native plants when conducting management work.
Always read and follow pesticide label directions. Application of pesticides may require a certification from the Agency of Agriculture, Food and Markets. The Agency website provides information on what applicator certification is needed.

Foliar spray: This method is used for dense populations and best left to a contractor. For extensive stilt-grass infestations, use of a systemic herbicide such as glyphosate is a practical and effective method if used with caution. Glyphosate is a non-specific herbicide that will kill or damage almost any herbaceous plant and possibly some woody plants it contacts. Grass-specific herbicides (graminicides) work very well on stiltgrass and if used correctly can reduce potential damage to woody or broadleaf plants.