by Ann Farnham, LLA

Stilt Grass (AKA Eulalia or Nepalese Brown Top), is botanically classified as Microstegium viminium. This is a notable invasive pest with which most Plant of the Month readers are probably familiar. Introduced into Tennessee as packing material for porcelain coming from Japan and China in 1919, it has now spread into 19 states from New York south to Florida.

Stilt Grass can seem invincible. Flowering occurs here in New Jersey in mid-August to September, and the yellow to red dried seeds are produced from August to mid-October in our area; the seeds are tiny, 0.1” in diameter, and one plant alone can produce 1000 seeds.  They spread, not through animal involvement, but water runoff, wind, our shoes, our clothes, mechanical equipment, mowing, tilling, flooding, and more. Although the plant is an annual, dying back at the first frost, the seeds remain viable for five to ten years, making quick control a fantasy. Germination occurs in late spring, before crabgrass emerges.  This grass thrives on roadsides, in ditches, moist woodlands, lawns, flower beds, and vegetable gardens.

Disturbed sites, moderate to dense shade, and moist, acidic to neutral soils are preferred. Stilt grass, like so many invasives, out-competes native plants. Animals avoid the plants and seeds, and deer ignore them while grazing on other plants nearby, which creates more space for the stilt grass. Huge patches develop as a result, threatening native communities, displacing natives, and degrading wildlife habitat. Large areas of dead Stilt Grass, after frost and before spring plants appear, are fire hazards. There seem to be no insect or diseases which attack Stilt Grass.

What does this invader look like? It has pale green to lime green, lance-shaped leaves which are arranged alternately along the stem and measure 1-4” long and 0.5” wide; there is a white stripe which goes along the mid-rib. It will reach 2 to 6.5’ tall depending on environmental conditions. The weak, narrow stems are erect to reclining, and where the stem node touches the soil it will take root and sprout more plants. The roots are shallow.

Control of Stilt Grass may take years, but there are guidelines which will help. Foremost, control attempts must be addressed before flowering and seed-set. In small areas, such as flower beds, 1. hand-pulling is easy, as the roots are shallow. However, do not be surprised when more appear in the spring; remember, the seeds live for years.  2. String trimmers are very effective if you can avoid whacking your perennials and shrubs. Remove the grasses and do not include them in compost piles or the city brush and grass clippings collection area. 3. A pre-emergent herbicide- such as Preen, corn gluten meal, Pendulum, Panoramic, or Oust – might help in the early spring. This is an annual effort.

Large areas can be weed-whacked, and post- emergent herbicides can be used. The post emergent herbicides include Roundup, Aquaneat, Finale, Assure 11, Aclaim and Barricade. Post emergent herbicides must be used very carefully, when rain and wind are not occurring, and where other, to-be-saved plants are not nearby. There are grass-specific herbicides as well.

Good Luck!

The Ewing Environmental Commission (eec@ewingnj.org) welcomes suggestions for the Plant of the Month from all Ewing residents.

To calculate the economic and ecological benefits of the trees on your property. go to treebenefits.com.