Introduction:
Canary grass (Phalaris arundinacea)
Phalaris arundinacea is a cool-season perennial grass that grows successfully in northern latitudes and can be invasive in wet habitats. Since it is tolerant of freezing temperatures and begins to grow very early in the spring, it can outcompete many other species. Any moist, fertile habitat provides good conditions for P. arundinacea. It is considered a serious threat in wet meadows, wetlands, marshes, fens, old fields, floodplains, wet prairies, roadsides and ditchbanks. The invasion is promoted by disturbances, such as ditching of wetlands, stream channels, deforestation of swamp forests, sedimentation, overgrazing and intentional planting. P. arundinacea tolerates frequent and prolonged flooding as well as submergence. It is moderately tolerant of drought and saline or alkaline soils. P. arundinacea spreads within sites by creeping rhizomes and forms dense and impenetrable mats of vegetation. New sites are colonised by seeds. P. arundinacea tolerates a small amount of shade, such as forest edges but not closed forest interiors.
Description:
Phalaris arundinacea is a robust, cool-season, sod-forming perennial grass that produces culms (stems) from creeping rhizomes. The culms grow 0.6 to 2m tall. The leaf-blades are flat, 0.2 to 2cm wide and up to 0.5m long. Flowers are arranged in dense, branched panicles that can exceed 5 to 20cm in length. Immature panicles are compact and resemble spikes, but they open and become slightly spreading at anthesis. Spikelets are lanceolate, 5mm long and pale. Most contain three florets, two of which are extremely reduced, linear and infertile. One of the distinguishing features of the genus Phalaris is the presence of some infertile florets. The lemmas in the infertile florets are approximately 1mm long while those of the fertile florets are 3 to 4.5mm long. The glumes are strongly compressed and wingless.
P. arundinacea is morphologically variable, and more than ten infraspecific categories (varieties, subspecies, forms and races) have been described. These categories are based on characteristics such as the amount of branching, leaf colour, size, shape and density of inflorescences. Differences in the height at maturity and in size, shape, and colour of the inflorescence may depend on the habitat. There are no known morphological features for this species that allow native individuals to be distinguished from non-natives.
Canary grass (Phalaris arundinacea) Distribution in North America shown in green.
Occurs in:
Estuarine habitats, lakes, riparian zones, ruderal/disturbed, urban areas, water courses, wetlands.
Habitat description:
Phalaris arundinacea can be classified as growing in semi-open and open habitats. Riparian habitats are at the greatest risk of being invaded and dominated by P. arundinacea, but any moist, fertile habitat provides good conditions for this species. It is considered a serious threat in wet meadows, wetlands, marshes, fens, old fields, floodplains, wet prairies, roadsides, ditchbanks. Streambanks, lakeshores, and shore swales also support the species. Invasion is promoted by disturbance, such as ditching of wetlands, stream channelization, deforestation of swamp forests, sedimentation, overgrazing, and intentional planting. Natural disturbances, such as scouring floods and low water conditions also promote invasion.
The “natural” varieties of P. arundinacea are well suited to periods of frequent and prolonged flooding, and it is never injured by severe winter weather. They grow especially well in clay/loam soil and in sand (if the water content is high enough) but do not do well in peaty soils. It is categorized as a hard water species. It occurs along brackish tidelands. The upper range of water pH tolerance been measured to 8.8. P. arundinacea is not shade tolerant but is moderately tolerant of drought and saline or alkaline soils.
Weed Management:
Close up of Canary grass (Phalaris arundinacea) stem.
Mechanical and Manual: Mechanical methods are aimed at removing stems, leaf canopy and seed heads before maturation. Cutting stems and mowing can expose the ground to light that will promote regeneration of native species. Clipping seed heads before maturation did not reduce dominance but clipping stems down to 8 cm tall every two weeks reduced its density. Discing soil and plants can stimulate the growth of native species.
Chemical: Several herbicides have been used to control Phalaris, including amitrole-T (3-amino-1,2,4-triazole ammonium thiocyanate), glyphosate (N-[phosphonomethyl]glycine) and dalapon (2,2-dichloro propionic acid). Tu et al (2001) reports good control by first mowing in late spring-early summer at the onset of flowering, then applying a foliar spray of Rodeo® in a 2% solution with either 0.5% Bio-88® or R-11® nonionic surfactant in fall, before the first frost. The formulation can be applied with a backpack sprayer or an ATV with a boom attachment.
Integrated management: Competitive crop management has been most effective when used in conjunction with prescribed burning. Desert saltgrass (Distichlis stricta) may be used as a “replacement species” in alkaline or saline soils where erosion may pose a problem after herbicide application and subsequent removal of P. arundinacea. Restoration of native wetland communities, partly by sowing a mixture of desirable species as early season cover crops and manipulating mixes of species may be a promising strategy to contain new infestations and restore native wetland communities.
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