Microstegium (c) University of Richmond (Va)

Microstegium is also known as Japanese Stiltgrass, Nepalese Brown-top, barnyard grass or bamboo grass. The name 'bamboo grass' comes from the fact that the leaves resemble bamboo leaves, long and pointy and fairly smooth. It is an invasive exotic that infests yards, parks, and fields throughout the Ellerbe Creek watershed. It grows statewide and is on the worst pest list for all of The Nature Conservancy's North Carolina regional offices.

Graceful and harmless-looking, Microstegium exploded in the Ellerbe Creek watershed after Hurricane Fran, back in 1996. It's currently found in Northgate Park and is rampant at Eno River state park where the rangers conceded that they considered it part of the "native" ecosystem at this point and are doing nothing to stop it. It has been reported at Hanging Rock, Pilot Mountain, and up on the Appalachian Trail.

Microstegium came from Asia as packing material in the early part of the 20th century. It thrives in moist places and spreads very rapidly along streams, trails, and roadsides. It looks like a dense, green rug overlaying native herbs and tree seedlings which simply disappear along with the wild species that depend on them. Seeds can survive in the soil for many years.

Microstegium looks a lot like a miniature bamboo plant with the elongated leaves (1 to 3 inches long), pointed at both ends, and alternating from nodes along the stem. Segmented stems grow 1 to 3 feet long in late summer, bending toward the ground and forming a dense, continuous mat. The plant has shallow roots and ranges up to about a foot tall (often less if the area is mowed).

Flowers are narrow spikelets at the end of the stems. In late September and early October, the spikelets contain seeds along their length.

For more images of Microstegium see
www.invasive.org/search/action.cfm?q=microstegium or
tncweeds.ucdavis.edu/esadocs/micrvimi.html

The seeds of this obnoxious plant can remain viable in the soil for 5 to 7 years. It is often one of the first plants to colonize disturbed areas (it can be transported in the tires of construction equipment), but the infestations have spread into undisturbed rural areas as well. The seeds seem to travel well in streams, among other vectors.

The time to fight Microstegium is when it is blooming (before the plants set their seeds). How can you prevent it from going to seed? It's surprisingly easy. Mow it, weed whack it, pull it, rake it (a hard tined rake works well on large clumps), or cover it with cardboard overlaid with mulch. In heavily infested areas, you will probably need to work on it for several years to get rid of it. But it's very easy to pull up, since it has weak roots, although they do get stronger as the season goes on.

Microstegium is an annual so all of next year's crop will have to come from seed. Any Microstegium you remove now means fewer seeds to produce more of this obnoxious weed next year.

One obstacle to controlling Microstegium is that the city is doing nothing about it on the greenway so there is a constant source of seeds to be spread around. They do mow it, so it's not as easy to recognize unless you take a close look. Mowing doesn't keep it from spreading, since it also spreads by rooting at stem nodes.

It's hard to deal with Microstegium by hand on a large scale. In 17 Acre Wood, it is mixed in with native sedges and wildflowers along the trail, which requires careful pulling to avoid pulling out the natives. Surprisingly, it has not yet taken over the whole 17 acres, but at least a couple years ago was concentrated along the trail. It was originally introduced to the preserve when a sewer line that parallels the large tributary broke, requiring heavy equipment to come in and make quick repairs. Their wheels carried dirt full of Microstegium seeds, which sprouted en masse the next year and have been spreading ever since.

One of the staff at NC Botanical Garden recently recommended using an extremely dilute solution of Roundup (0.5%), which is just strong enough to do in the Microstegium, but reportedly leaves the perennial natives uninjured. It helps if the Microstegium has grown over everything else, so that it acts as a shield, catching the herbicide before it reaches the natives underneath.

Steve Hiltner says "When I was living in town, I would scramble each fall about now to find the time to do Microstegium patrol, which involved walking along the leading edges of the infestation, back in the woods near the trail, spraying the Microstegium with a 2% solution of a generic brand of Roundup to prevent it from spreading further into new areas of the preserve. Back in the woods, there are hardly any natives growing, so there wasn't any worry of killing any desirable plants. Sometimes I would find isolated clumps of it in otherwise uninfected areas, and would spray those. There was also some of it moving into the preserve from the backyards in the 2000 block of Sunset Avenue. It really claims a woods quickly if this sort of patrolling isn't done every year."

Microstegium frequently mingles with jewelweed, a native with a pretty tubular orange flower. The jewelgrass, which is also an annual, casts its seed about earlier than Microstegium, so should come up the next year if the mixed stand is sprayed or mowed or pulled in September.

It is worth noting that there are herbicides that are specific to grasses and will not harm non-grass plants at all. These chemicals are used frequently when forest plantations are established because grasses have the potential to smother new seedlings during their first year of growth. These herbicides might be a good choice for controlling Microstegium in forested areas because most of the other understory plants in those areas are not grasses. Down the road there may be an herbicide on the way that kills only Microstegium. If any of you know plant physiology, you may remember that plants can be classified as C3 or C4. These categories refer to the pathway by which carbon is metabolized. Most plants are C3. C4 plants are generally warm season grasses, like maize (corn) that are adapted to full sun. Microstegium seems to be unique in that it is a C4 grass that is adapted to shade. Researchers are hoping to find an herbicide that affects only C4 grasses. If/when they succeed, they will have a chemical to kill Microstegium that will not harm any of the native flora in our forests.

It can be difficult to deal with Microstegium and constant vigilance is important but it CAN be managed (although it's so widespread it probably cannot be completely eradicated).

NOTE: Recent research by impressive medical laboratories at outstanding universities continues to show a link between Roundup and non-hodgkins lymphoma, a disease that has increased significantly over the last decade.

See www.nps.gov/plants/alien/fact/mivi1.htm