Compressed rush, roundfruit rush, Juncus bulbosus Linnaeus, 1762, J. supinus Moench

Juncus compressus is easy to confuse with J. gerardii, another non-native species in the Great Lakes (Online Atlas of British & Irish Flora 2012).

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

Environmental	Socioeconomic	Beneficial

Juncus compressus has a moderate environmental impact in the Great Lakes.
Realized:
Once this species establishes in an ecosystem, it will likely persist (Stuckey 1981 in Vincent and Cusick 1998). In wetland environments, rushes will out-compete other plant species (Stevens and Hoag 2003).

Potential: 
Juncus compressus poses a competitive threat to the native and naturalized Juncus spp. in the Great Lakes, especially those listed as threatened or endangered, including J. alpinus auct. non Vill., J. ambiguus Guss., J. balticus Willd., J.biflorus Elliot, J. marginatus Rostk. var. biflorus (Elliot) Alph. Wood, J. brachycarpus Engelm., J. brachycephalus (Engelm.) Buchenau, J. dichotomus Elliot, J. diffusissimus Buckley, J. ensifolius Wikstr., J. greenei Oakes & Tuck., J. interior Wiegand, J. militaris Bigelow, J. pelocarpus E. Mey., J. scirpoides Lam., J. secundus P. Beauv. ex Poir., J. stygius L., J. stygius L. ssp. americanus (Buchenau) Hultén, J. subcaudatus (Engelm.) Coville & S.F. Blake, J. vaseyi Engelm. (USDA NRCS 2012c).
There are no known records of hybrids between J. compressus and other species, but this genus contains several natural hybridizations (USDA NRCS 2012a). Furthermore, several species of this genus have synchronous flowering to attract pollinators, which creates the potential for outcrossing (Michalski and Durka 2007).

In the United Kingdom, the roots of Juncus spp. have been observed to trap water and alter the hydrology in shallow water environments (Centre for Aquatic Plant Management 2004).

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

Realized:
Many Juncus spp. serve as a host for larvae of Coquillettidia, a genus of mosquitoes that can serve as a vector for various animal-borne vectors (Sérandour et al. 2010).

Potential:
Juncus compressus may be confused with or pose a competitive threat to native rushes that are culturally important, including J. arcticus ssp. littoralis and J. effusus (USDA NRCS 2012b).

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

Realized:
Numerous animals feed on the seeds of rushes, including waterfowl, songbirds, quail, jack rabbit, cottontail, muskrat (also feeds on roots and rhizomes), porcupine, gopher, and other small mammals (Martin 1951 in Stevens and Hoag 2003). Juncus spp. provide habitat for amphibians and various wetland birds, as well as spawning ground for some fish species (Stevens and Hoag 2003).

The dense root and rhizome system of Juncus spp. enable them to survive periods of stress (drought, flood, etc.), accumulate soil, and provide erosion control (Stevens and Hoag 2003).

Potential:
Cattle, horses, and sheep will graze on Juncus spp., but their specific value as fodder is unknown (Centre for Aquatic Plant Management 2004, Cosyns et al. 2005).

The rhizome matrix can support numerous bacteria, which can be used in wastewater treatment (Stevens and Hoag 2003).

Regulations (pertaining to the Great Lakes region)
There are no known regulations for this species.

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

Control
Biological
Aphids may occasionally feed on Juncus spp., but most rushes are fairly resilient to extensive damage from insect or diseases (Stevens and Hoag 2003). Cattle, horses, and sheep graze on Juncus spp., but the extent of control gained from grazing is unknown (Centre for Aquatic Plant Management 2004, Cosyns et al. 2005).

Physical
There are no known physical control methods for this species.
The rhizome matrix of Juncus spp. enables it to withstand periods of drought and flooding; water level fluctuation is not recommend as a physical control method (Stevens and Hoag 2003).

Chemical
Sethoxydim will target most grass species and should not affect nearby broadleaf herbs, sedges, or woody plants (IPAW 2012). Glyphosate and ammonium salt of imazapyr will control J. compressus, but are non-selective and should be applied carefully (Centre for Aquatic Plant Management 2004) Glyphosate should be sprayed directly onto foliage in mid-late summer (Centre for Aquatic Plant Management 2004).

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