Alopecurus geniculatus var. geniculatus; Alopecurus pallescens

Stems are numerous and erect to decumbent (Klein 2011). Leaves are green to gray-green; flat (Klein 2011). The sheath is open; auricles absent (Klein 2011). The ligules extend 3–5 mm high; pointed or blunt with smooth or ragged edges (Clayton et al. 2006). The flat leaf blade surface is scaberulous; rough on the upper surface; 2–6 mm wide; 2–12 cm long (Clayton et al. 2006).

Flower-head and Flowers:

Inflorescences are pale green to purplish panicles arranged in linear spikes; 2-7 cm tall; 0.3-0.7 cm wide; cylinder shaped; tapered at end (Clayton et al. 2006, Klein 2011). Panicle axis has rounded ribs (Clayton et al. 2006).

Spikelets are solitary; 1.9-3.5 mm; ascending hairs on edges (Clayton et al. 2016). Fertile spikelets have 1 floret; oblong pedicels; rhachilla extension absent (Clayton et al. 2006, Klein 2011). Upper and lower glumes are oblong; 2.5–3.5 mm long; membranous; keeled; 3–veined with primary vein ciliate (Clayton et al. 2006). Glumes are connate at base; exceeding or reaching apex of florets; long hairs on the keel; silky hairs across the back (Clayton et al. 2006, Klein 2011). Lemma are oblong; membranous; keeled; 4 –veined (Clayton et al. 2006, Klein 2011). Lemma margins are connate below, apex truncate, 1-awned (Clayton et al. 2006). The awn is bent and attached 0.5 mm above the lemma base and extend well beyond the glumes (Klein 2011). Palea absent or minute (Clayton et al. 2006). Flower lodicules absent; 3 anthers; 1.5–2 mm long (Clayton et al. 2006, Peeters 2004). Stigmas protogynous; terminally protrude; pubescent (Clayton et al. 2006). Ovary glabrous (Clayton et al. 2006).

Other Features:

Generally, a small low grass, stems start off along the ground (Fofonoff et al. 2003). Culms decumbent; 15–45 cm long; 1–5 noded (Clayton et al. 2006). A. geniculatus can root at nodes (Klinkenberg 2010, Klein 2011). Fruit is a caryopsis with adherent pericarp (Clayton et al. 2006).

The first reported specimens from the Great Lakes basin were collected in 1882-1886 in Lake Erie drainage (Fofonoff et al. 2003). 

Found in 4 counties in Michigan: Alpena, Lenawee, Macomb, and Saginaw (University of Michigan: Herbarium 2016). First collected Alpena County in 1988 (University of Michigan: Herbarium 2016).

A. geniculatus reproduces sexually by seeds and can reproduce vegetatively by rooting at stem nodes (Klinkenberg 2010). The amount of seeds produced per plant and the maximum period of viability is unknown, however, seeds remain viable in the soil for at least three years (Roberts 1986). A. geniculatus is a hemicryptophyte and epibenthic, it germinates and emerges within a half inch of the soil surface (Fofonoff et al. 2003, Plant Atlas 2016). Seeds have a mass of approximately 0.8 mg (USDA 2011) and therefore can likely be transported short distances by wind. Its most active growth period is in the spring, and it flowers June-August (Peeters 2004).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental

Potential:

Alopecurus geniculatus may flourish at some sites, though overall production is generally low (Peeters 2004). Infestations of A. geniculatus have occurred at up to 10% ground cover in Alaska and it has been documented to be able to form monospecific stands in disturbed wetlands (AKEPIC 2016), therefore it has the ability to increase the density of graminoid layers in wet areas (Klein 2011). It readily colonizes bare mud, where it can become very lush, but avoids both very acidic and very alkaline soils (Plant Atlas 2016). A. geniculatus is typically found in nutrient-rich soils and is described as moderately to very demanding of soil nutrients (Peeters 2004) and may reduce populations of other species on nutrient-rich soils (Kalusová et al. 2009). This suggests that A. geniculatus could influence nutrient availability or soil chemistry (Klein 2011, Peeters 2004). A. geniculatus abundance increased positively with soil phosphorus levels and it is speculated that it could be a competitive grass species in nutrient-rich soils (Kalusová et al. 2009). However, A. geniculatus is classified as a generally poor competitor (Peeters 2004). It may dominate wet microsites, and if infestations reach sufficiently high densities, it could alter community structure in invaded wet areas (Klein 2011, Peeters 2004). Although it is capable of hybridizing with the native short awn foxtail (Alopecurus aequalis), only sterile offspring are produced (Klein 2011).

There is little or no evidence to support that Alopecurus geniculatus has significant socio-economic impacts in the Great Lakes.

Potential:

Alopecurus geniculatus could contaminate seed or hay crops, which would aid in the spread of this species and could lead to degradation of the agricultural lands where the contaminated crops are used. In particular, it is documented the have contaminated ryegrass straw produced in Washington/Oregon and shipped to Alaska (Conn et al. 2010). A. geniculatus grown for hay has been linked with several fungi species that contribute to pulmonary diseases in horses (Seguin et al. 2010).

There is little or no evidence to support that Alopecurus geniculatus has significant beneficial effects in the Great Lakes.

Potential:

Alopecurus geniculatus is a grass species used for forage and hay production in Europe and Russia (Malyshev 2009, Seguin 2010). It can tolerate trampling and grows effectively in grazed grasslands, but according to Peeters (2004), it does not have exceptional forage quality and is not recommended as a compatible species with other forage grasses. Furthermore, it appears to have a greater association with fungi responsible for equine pulmonary disease relative to other forage species (Seguin 2010).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control:

Biological

There are no known biological control methods for this species. Related species Alopecurus pratensis has been reported to be susceptible to a number of fungal diseases in Oregon (Hannaway & Myers 2004).  In the United Kingdom the seeds of A. pratensis have been found to be empty when infested with grubs of gall midges; Contarinia merceri, Dasyneura alopecuri, Stenodiplosis geniculati (Barnes 1930). Several species of nematodes have also been isolated from A. pratensis; Heterodera avenae, H. schachtii, Pratylenchus neglectus, P. penetrans, Subanguina radicicola, and Tylenchus hordei (Duke 1983).

Physical

Alopecurus geniculatus tolerates periods of waterlogging and flooding (Toogood et al. 2008). This species does not grow as well under a drier water regime (Toogood et al. 2008). Moreover, in locations where water level manipulation is used for wetland management, flooding should not be used as a method for controlling this species.

Frequent cutting and mowing can reduce Alopecurus geniculatus plant yield and prevent seeding (OSU 2005). Digging and hand pulling methods have not been investigated but may be effective because the plants lack rhizomes (Klinkenberg 2010).  A. geniculatus has the ability to reproduce via seed dispersal and vegetatively from roots nodes (Klinkenberg 2010). Due to its epibenthic nature if seeds are driven far below the surface, they are unlikely to be able to germinate (Fofonoff et al. 2003). A variety of tilling methods can be used both to kill seedlings after emergence and to bury seeds deep into the soil to prevent germination (Curran 2009). Seeds can remain viable in soil for at least three years (Roberts 1986). Therefore, management activity would be most effective if performed before seeds have a chance to disperse.

Chemical

The effectiveness of herbicides in controlling water foxtail is unknown. Complete eradication of a related species, Alopecurus pratensis (meadow foxtail), was achieved when treated in late summer with glyphosate at 1.0 kg/ha, 0.89 lbs.’/ac (OSU 2005). Use of fluazifop also controls Alopecurus pratensis, but has also been reported to be toxic to fish and aquatic invertebrates (OSU 2005). Absorption of sethoxidon, another herbicide used to control Alopecurus pratensis, can be increased when it is simultaneously applied with oil adjuvant and a non-ionic surfactant (OSU 2005). If managers expect dense populations of foxtail species, grass herbicide rates may need to be increased or the application timing altered to include split applications or post-emergence control (Curran 2009).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.