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Invasive, Exotic Plants of the Southeast


Japanese Grass

Japanese Grass

Common Name: Japanese Grass, Nepalese Browntop, Stilt Grass

Scientific Name: Microstegium vimineum

Identification: Japanese Grass is a sprawling annual grass 0.5 to 3 feet in height.  Alternate flat leaves, 2 to 4 inches in length, project outward from the stem.  The stem is wiry and slender and green to purple.  The flowers are 3-inch spikes and appear from August to October.  Seeds are small and elliptical shaped and mature in September to December.

Ecology: Japanese Grass occurs along streamsides, forest edges, roadsides, swamps, lawns, and right-of-ways.  This grass is shade tolerant and spreads primarily by seeds moved by animals, people, and water.  Japanese Grass is extremely invasive because it is a prolific seeder.  Each plant may produce 100 to 1000 seeds that will remain viable for 5 or more years.  Japanese Grass has no known wildlife value.  Japanese Grass degrades habitat quality and replaces native forbs.

Plant Control: Spray with a glyphosate herbicide before seed set (early Sept).  In sites where the Japanese Grass is mixed in with other non-target plants, try spray-topping (using a low strength solution that will brown out the Japanese Grass but will not kill the other plants like ferns, wildflowers, clovers). With this method, Japanese Grass can be controlled with as little as ½ oz. of plain glyphosate (Accord or Rodeo) mixed with ¼ oz. Agri-dex Spray Adjuvant per 2 ½ gallon sprayer.  Alternatively, apply a selective herbicide such as sethoxydim (Vantage or Poast).  For small infestations, hand pulling, weed-eating, or mowing in early September before seed maturation may provide adequate control. Monitor yearly and control as needed to prevent reinfestation.   
Alternative Native Species: Switchgrass (Panicum virgatum), Indiangrass (Sorghastrum nutans), Splitbeard Bluestem (Andropogon ternarius), Little Bluestem (Schizachyrium scoparium)

When using herbicides remember to follow label-recommendations.  Any mention of trade, products, or firm names is for descriptive purposes only and does not imply endorsement by North Carolina State University.

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