By Nick Koenig
Japanese Stiltgrass (Microstegium vimineum), often called Stiltgrass or most commonly Microstegium, is a shade tolerant grass in the Poaceae/Grass plant family. This is the second most biodiverse plant family in Kentucky right behind Asteraceae/Sunflower family. Given the massive number of species in the family and the distinctness between members in the family, recognizing Microstegium can be tricky but I hope to help so that native plant lovers can start to remove this species from their landscape!
Description
It is likely if you have hiked along a creek in a disturbed area or walked along a road, you have probably come across Japanese Stiltgrass and thought nothing of it. However, this should be of great concern to landowners/land managers/native plant enthusiast. Once you can competently identify the next patch of Microstegium you come across, you can help eradicate it from the area.
DISTINCT FEATURES
By far, the most distinctive feature for Microstegium that I use in field identification is the faint silver line running down the middle vein of the leaf. This characteristic is not as prominent and distinctive among any other native grasses in Kentucky.
APPEARANCE
Japanese Stiltgrass is a “weak-stemmed annual, branching, decumbent [running along the ground then rising up], rooting at the lower nodes [points where leaves or stems come out].” (Weakley 2015).
LEAVES
As described in the Flora of the Southeast (Weakley), the leaves are ovate-lanceolate (meaning oval and much longer than wide, roughly 2.5-7 times longer than wide ), 2-10 cm long tapering at the base.
HABITAT
Microstegium can most likely be found in “disturbed areas, colonizing moist, rich soil, especially in floodplains” such as along a creek bank where it is often found (Weakley 2015). Due to the Japanese Stiltgrass’s ability of being shade-tolerant, the species can make deep incursions in a forested area.
Where Found in US
Japanese Stiltgrass is found across Kentucky, in any just about any suitable habitat in almost every county based upon niche models being developed at Eastern Kentucky University (Koenig et al. in prep.).
How it Got Here
Japanese Stiltgrass is native to Asia and was introduced to Tennessee in 1919, but since has spread to much of the eastern United States. It is believed that the plant was brought in from the porcelain industry and when packaging the porcelain, they used Microstegium to protect the ceramics. Unlike other invasive species, the species is not sold in nurseries or garden centers, thankfully; however, the species is very successful at taking over in new habitats, so it is crucial to stop the spread.
Ecological Impacts
As listed as a severe threat by the Kentucky Pest Plant Control’s list of invasive plants, it is no surprise Microstegium has severe ecological impacts. It has been researched and found that Microstegium reduces the diversity of plant life and increases the nutrient cycling in the areas that it invades. This causes a rip in the fabric at which native plants are adapted and evolved to live from generation to generation. When there is a break in the plant life, there is a break in all the life the plants support. Therefore, it should be of the utmost importance from land managers to plant enthusiasts to remove any and all populations of Microstegium from the local flora.
How to Control
There are three main methods for controlling Microstegium: manual pulling, mowing, or herbicide.
MANUAL
Hand-pulling is by far the cheapest of three options as it requires only time and patience. Microstegium is extremely easy to pull out of the ground, roots and all, especially compared to other nasty invasives. The best time to pull Microstegium is July to late August as this prevents the seeds from spreading or giving it enough time to create new flowers. Since the grass is an annual, after a few years of pulling (maximum five years), it is possible to remove this invasive from the area, but you have to make sure you don’t miss a small population as it can recolonize an area if you are not careful.
MECHANICAL
Mechanical removal could include mowing or weed eating. This method should be implemented in mid to late August, and if the population of Microstegium has completely taken over the area. If the area is too large for hand removal and there are some natives, it would be best to avoid the native species, but it should be the main priority to get rid of the Microstegium, then to work on reestablishing native plants. Similarly, to hand pulling, mechanical removal will take potentially three to five years to completely remove the invasive.
HERBICIDES
The last resort would be chemical removal. It is recommended to use either a non-selective herbicide (such as 2% glyphosate) during June/July to kill populations of Microstegium, or one can use a grass-specific herbicide (such as Select, Select Max, Post, Fusilade3) also during June/July. For larger areas, this may be the only option to remove the invasive; however, mechanical and manual pulling will be the safer options.
If any readers have questions, please feel free to email the author, Nick Koenig, at the following email address: nicholas_koenig1@mymail.eku.edu
Information sources:
1. Koenig, N., R. Pace, and J. Koslow. Field Assessment & Niche Modeling of Populations of Microstegium vimineum (Trin.) A. Camus in Lilley Cornett Woods. Manuscript in Preparation.
2. Microstegium vimineum– Invasive Plant Atlas –. Accessed May 2020.
3. Stringer, J. Invasive Plant Hit List: Japanese Stilt Grass. Kentucky Woodland Magazine. Volume 3, Issue 2.
4. Weakley, A.S. Flora of the southern and mid-Atlantic states, working draft of May 2015. University of North Carolina Herbarium, North Carolina Botanical Garden, Chapel Hill, NC.
Associate Editor – Nick Koenig
Nick Koenig is a senior Biology Major with a Botany Concentration at Eastern Kentucky University. At EKU, he serves as the Co-President of the student environmental group, Green Crew, works as a Biology Tutor, and volunteers in the Greenhouse. He fell in love with plants through gardening and the Kentucky State Fair but has continued with his passion through research at EKU.