Microstegium vimineum | Japanese stiltgrass
Regulated invasive species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].
Introduction pathways - 1
Introduction pathways subclass - 1
Contaminant nursery material, Seed contaminant
Introduction pathways - 2
Introduction pathways subclass - 2
NAPRA Ireland risk assessed
An annual grass with a bamboo-like appearance but isn't woody (Q-bank, 2017). Grows up to 1.5m tall and has 'a sprawling habit' (EPPO, 2016). Leaves are pale green, alternate, lanceolate, 5-8cm long and 2-15mm wide with a distinctive silver central vein and sparse hairs on both sides (GISD, 2015). Flowers, which are tiny and carried on a raceme appear mid-Autumn (GISD, 2015). Seeds (caryopses) are yellow or reddish. Roots are shallow and fibrous.
The characteristics of early and fast growth, early maturation, plentiful seed production and tolerance of a wide range of conditions are common to many invasive species (EPPO, 2015). Microstegium vimineum possesses all these features. Rapidly forms dense monocultural stands, thus reducing biodiversity by crowding out native species including tree seedlings. Increases soil nitrification enabling the plant to maintain the monocultures (Lee et al., 2012). Post seed set the dry litter of M. vimineum is very slow to breakdown, which can inhibit native spp. germination and growth (EPPO, 2015). The dry litter also increases the fire risk as well as fire intensity (Flory et al., 2012). Fire promotes the establishment of M. vimineum producing a huge increase in vegetation in the season following a fire (Flory et al., 2012). Favours damp, shaded, disturbed sites but tolerates a wide range of soil moisture (EPPO, 2015), pH and light conditions, from full sun to deep shade (EPPO, 2015). However, dry sandy areas may be less vulnerable to invasion (EPPO, 2015). Increases the rate of carbon cycling thus reducing soil carbon content and reducing soil fertility (Strickland et al., 2010).
Reproduces by seed, which can remain viable for 5 years (Q-bank, 2017). Is both self and cross-fertile. Produces large numbers of seeds (EPPO, 2015; GISD, 2015), which are dispersed by animals, water and humans on boots or clothes. Seeds can survive under water for up to 10 weeks (GISD, 2015). Spreads by producing roots at stem nodes (GISD, 2015).
Pathway and vector description
Pathways into Eastern Europe could be via soil contamination of second hand machinery, birdseed, soil around ornamental plants, people's clothing and shoes (EPPO, 2015). Once established it spreads by seeds, which can be carried to new areas by anthropogenic activities, animals and on water (EPPO, 2015). Transport corridors within countries e.g. Roadsides, forestry access roads etc. allow the plant to rapidly spread. Ireland is on the list of countries expected to be most at risk of invasion but the Mediterranean area is considered most suitable for establishment (EPPO, 2015).
Mechanism of impact
Easy to control if detected early before it has time to build up a seed bank. However, it spreads rapidly (EPPO, 2015). Control methods will need to be repeated over a few seasons and then monitored regularly for the presence of seedlings.
The general public should be educated about the identification and ecological impact of the plant. Interested parties, for example foresters, landowners, hikers and those using the waterways should be targeted in particular.
Compulsory certification of decontamination of second hand machinery/equipment from infested areas should be considered.
Handpulling prior to seed set is an effective means of control for smaller populations (EPPO, 2016; Q-bank, 2017).
Larger stands in accessible areas can be mowed prior to seed set (EPPO, 2016; Q-bank, 2017).
Readily controlled by grass selective herbicides (EPPO, 2016; Q-bank, 2017). It may be necessary to use a glyphosate formulated for used near water in some situations.
Favours damp, shaded, disturbed sites but tolerates a wide range of soil moisture (EPPO, 2015), pH and light conditions, from full sun to deep shade (EPPO, 2015). Will invade habitats such as forestry, damp woodland, old pasture, roadsides, lawns, riparian zones particularly where the ground has been disturbed.
Temperate Asia, Tropical Asia
Not yet found in western Europe (Q-bank, 2017). Invasive in north and central America (EPPO, 2015). Has been found in Turkey and southern Caucasus and was therefore added to the list of Invasive Species of Union Concern in 2012. Also found in Azerbaijan, Georgia and northern Caucasus (EPPO, 2015).
Native to Bhutan, China, India, Iran, Myanmar, Nepal, Philippines, Russia, Taiwan, Thailand and Vietnam.
Records submitted to Data Centre in 2021
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How can you help
Report any sightings to the National Biodiversity Data Centre.