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Quackgrass Elytrigia repens (L.) Nevski; Agropyron repens (L.) Beauv. |
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Keys to Identification:
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This information courtesy of the Colorado Natural Areas Program Family: Poaceae (Grass) Other Names: couchgrass USDA Code: ELRE3 Legal Status: Colorado Noxious Weed List B Identification Growth form: Perennial grass Flower: Slender spike, resembling wheat heads Seeds/Fruit: Spikelets are arranged in two long rows, borne flatwise to the stem. Florets are awnless, or with short straight awns. Leaves: Leaf blades are flat, pointed, 0.25 0.5 inches wide, and have small ear-like appendages (auricles) at the junction of the blade and the sheath (Whitson et al 1996). Stems: Mature plants are usually 1-3 ft tall and have erect stems. Roots: Rhizomes are yellowish-white, sharp pointed, and somewhat fleshy. Seedling: Both leaf sheath and blade are hairless or sparsely hairy. Clasping auricles and a short membranous ligule are present (Carey et al. 1993). Impacts Agricultural: Quackgrass reduces productivity in crops, rangeland, and pasture Ecological: Quackgrass is a rapid invader and quickly stabilizes moist eroding soils. It invades mixed-grass prairies, roadsides, ditches, crop fields, gardens, yards, and just about any disturbed, moist area. It is believed to be allelopathic (Whitson et al. 1996). Habitat and Distribution General requirements: Quackgrass is well adapted to moist soils in cool temperate climates. Optimum temperatures for growth are between 68 and 77 degrees F. Quackgrass is only moderately shade tolerant. Plant vigor is reduced when shading exceeds 50%. Some species that are commonly associated with quackgrass include sedge (Carex spp.), bulrush (Scirpus spp.), rush (Juncus spp.), crested wheatgrass (Agropyron cristatum), indiangrass (Sorghastrum nutans), big bluestem (Andropogon gerardii), little bluestem (Schizachrium scoparius), smooth brome (Bromus inermis) Kentucky bluegrass (Poa pratensis), and Canada thistle (Cirsium arvensis) (FEIS 1998). Distribution: Quackgrass is widely distributed in North America. In Colorado, quackgrass is typically found between 4,800-10,000 feet. Historical: Introduced from Europe Biology/Ecology Life cycle: Primary rhizome growth begins in early spring and then again in September and October with the onset of fall rains and cooler temperatures. Quackgrass flowers from June through August. Cross-pollination is necessary for seed production. Seeds germinate in fall or spring and plants are capable of producing seeds more than once per season. Mode of reproduction: Quackgrass propagates mainly by rhizomes but also reproduces by seed. Seed production: No information available Seed bank: Seeds may remain viable for up to 10 years Dispersal: No information available Hybridization: Although quackgrass is considered an undesirable weed species it is often crossed with other wheatgrasses to create hybrids for grazing. Integrated Management Summary Quackgrass is an early seral species in disturbed areas. This species initially forms a dense clump through extensive tillering. The following season plants may expand and form patchy to pure stands (Rutledge and McLendon 1998). Combining mowing or burning with herbicides may the most effective way to control quackgrass. Quackgrass may also be gradually replaced by other species through natural succession processes (Rutledge and McLendon 1998). References
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