Natural History: Japanese stilt grass is an annual grass first introduced into the United States as a result of its use as a packing material for porcelain (giving rise to its other common name, Chinese packing grass). First identified in Tennessee in 1919, it has since spread to most of the states east of the Mississippi. The seeds are small and easily transported by boots, tires, water, allowing it to move very quickly from one site to another.

Range and habitat in Indiana: The species first appeared in southern Indiana in the early 1990’s and has moved northward at a steady pace. It first appears along roads, trailheads and trails, and then moves into adjacent forest. It is now well established through portions of south central Indiana and in summer of 2004 was found as far north as Turkey Run and Shades State Parks (west central Indiana). At this rate, it will reach northern Indiana in a few years.

Identification: Good news - this is one of the few grasses that are readily identifiable even without flowers or fruits. Look for a distinctive silvery stripe down the center of each upper leaf surface. The leaves are around 3 inches long, lance-shaped, and a bit asymmetrical. The plant has a sprawling habit and grows slowly through the summer months, ultimately reaching heights of 2 to 4 ft. (reaching the larger heights where the plants receive more light and water). Slender stalks of tiny flowers are produced in late summer (August-September). The fruits mature soon after flowering and upon maturation immediately fall from the plant. The plant dies back completely by late fall, leaving orange-tinged dead plants sprawled over the ground.

Reproduction: Stilt grass reproduces exclusively by seed. Individual plants may produce 100 to 1,000 seeds that fall close to the parent plant. Seed may be carried further by water currents during heavy rains or moved in contaminated hay, soil, or potted plants, and on footwear. It is not a coincidence that this species almost always shows up first on public land at trailheads - hiker’s boots are responsible for moving it around. Stilt grass seed remains viable in the soil for five or more years and germinates readily.

Impacts: Japanese stilt grass is especially well adapted to low light conditions, making it a serious threat to our forest communities. Once introduced along roads, trails, or other disturbed areas, the grass moves into the understory of forests. It forms a complete lawn in the understory, out competing and displacing native wildflowers, ferns, and tree seedlings. Where white-tail deer are over-abundant, they may facilitate its invasion by feeding on native plant species and avoiding stilt grass.

Control: PREVENTION is the best answer! If it is not yet in your area, keep it out by being sure to brush your boots after visiting forested areas in central or southern Indiana. Do not carry this invader into new areas on your boots. Once it is established in an area, the species can be controlled in a couple of ways:

• Manual/Mechanical — For very small infestations, simply pull the plants out of the ground before they flower. For larger areas, weed whack the plants to the ground in September, shortly before it produces seed but too late for it to regrow before the first frost. Since it is an annual, preventing the plants from setting seed is all you need to do to eliminate the species from an area. Of course, it will be necessary to pull or mow areas again each year until all the

• Chemical — For extensive infestations, where mechanical methods are not practical, systemic herbicides such as glyphosate (tradename RoundUp, or Rodeo in wetland sites), or grass-specific herbicides like flauzifop-p-butyl (tradenames Fusilade or Fusion) are effective. Spraying areas with a very dilute solution of Fusion (1/2%) plus a surfactant has been very successful at killing stilt grass without impacting other species, even perennial grasses.

Plants should be sprayed between June and August, when the plants are actively growing but before flowering. Spraying is generally more effective earlier in the summer and less effective during droughty periods.

Additional information:

http://tncweeds.ucdavis.edu/esadocs/documnts/micrvim.rtf

http://www.nps.gov/plants/alien/pubs/midatlantic/mivi.htm,