Weed potential and threat to biodiversity
Like other ponded pasture grasses, Echinochloa polystachya may be a threat for open waters outside its native range (Hannan-Jones et al., 2008). It spreads easily and, once established, it is impossible for native species to establish again. German grass has colonized banks, shallow margins of rivers, lagoons and swamps as well as non-target areas (Holm et al., 1991). In Australia, German grass was found to threaten the habitat of water birds such as waterfowl, magpie goose and pygmy-goose, by displacing native plant species or by closing open waters, on which and where they feed, respectively (Garnett et al., 2000). Echinochloa polystachya is considered a weed in many countries including Mexico, Argentina, India, DR Congo and Chad (Holm et al., 1991). In Australia, its weed control management must be planned (Hannan-Jones et al., 2008). Therefore, its import and new establishment are not recommended (US Forest Service, 2013). It is considered a weed in rice fields in Louisiana (affecting 5000 - 6000 ha) and Java (Griffin, 2006; Michael, 1989).
Fire potential
During the dry season large amounts of dry matter of Echinochloa polystachya may increase susceptibility to fire, and fire intensity (Hannan-Jones et al., 2008).