Japanese stiltgrass is the most rapidly spreading invasive plant in Brown County. If you
have stiltgrass on your property, along your road, or in your woods, control the plant as
soon as possible. This plant is a serious threat to the health and diversity of our woodlands
in Brown County.
Also known as: Japanese grass, Nepalese browntop
Origin: Native to Japan, Korea, China, Malaysia, and India, Japanese stiltgrass was first
identified in the United States in Tennessee, in 1919. It may have escaped from its use as
packing material for porcelain. Chris Evans, University of Illinois, Bugwood.org
Description: Japanese stiltgrass is a sprawling annual grass which can grow up to 4 feet tall. It has alternate, lance-shaped leaves 1-3 inches long with a pale, shiny midvein slightly off-center. Its stem is slender and alternate-branching with nodes and overlapping sheaths. Slender stalks of tiny flowers are present from late summer into fall, followed by dry fruits which may remain into winter.
Habitat description: This annual grass does best in the partial to heavy shade of forest environments. Producing hundreds of seeds per plant, it colonizes bare soil in recently disturbed areas. This grass can be noticed rapidly spreading along the arteries of our roads, trails and streams. Roads and trails that previously appeared relatively bare in mid-summer, now are lined with a ribbon of green growth. This grass is becoming very abundant in the Salt Creek and Bean Blossom Creek floodplains. Thousands of plants can be seen growing along the Green Valley hiking and biking trail within the State Park.
Distribution: Due to its modes of dispersal, stiltgrass is commonly found along streams, trails, and roadsides, and in ditches. It also colonizes lawns, fields, wetlands, forest edges, and open woods, among other habitats.
Problem: Japanese stiltgrass spreads quickly to form large patches, outcompeting and displacing native plants. It tolerates a wide range of ecological conditions, from full sun to shade, and from moist soil to dry. Its seeds are dispersed by water, hikers, and vehicles. White-tailed deer may facilitate its spread by grazing on native plants and avoiding stiltgrass.
Control: Controlling Japanese stiltgrass is a multi-year project. The sooner you can detect stiltgrass and begin removal the better off you will be. The goal in controlling stiltgrass is to prevent the plant from going to seed. Once it begins going to seed you will have to treat the area for several years to exhaust the seed bank. Once detected, stiltgrass can be manually pulled if it is a very small population. You may have to pull several times throughout the season. Mowing is typically not effective due to the timing requirements. Mowing has to occur late in the season when flowering occurs, but before mature seed is present. Mowing too early will allow the plant to flower and set seed. Mowing too late will spread seed from one place to another.
Herbicide control of Japanese Stiltgrass: Japanese stiltgrass is best controlled with a grass-specific herbicide which contains the active ingredient fluazifop-P-butyl, sethozydim, or fenoxaprop-ethyl. These chemical can typically be applied at a low concentration 1-3% with ¼% of non-ionic surfactant added. Follow the label direction for the herbicide you choose. Glyphosate (e.g. Round-up related products) can be used to control stiltgrass. Glyphosate is a non-selective herbicide and will kill the stiltgrass and all associated plants. This is a viable option for extremely heavy areas of stiltgrass where the stiltgrass has already out competed most plants or for small patches were you are willing to tolerate a little collateral damage to control the stiltgrass. Glyphosate at 3% is adequate to kill stiltgrass, or follow the label instructions for easy to kill weeds.
USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all recommended personal protective gear and clothing. Contact your state department of agriculture for any additional pesticide use requirements, restrictions or recommendations.