Quackgrass [Elytrigia repens (L.) Nevski][AGRRE][CDFA list: B] Photographs Map of Distribution

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SYNONYMS:couchgrass, wheatgrass, quitchgrass, witchgrass, shellygrass, knotgrass, twitchgrass, devils-grass, scutch-grass, quickgrass, whickens, dog grass, wiregrass, Agropyron repens (L.) Beauv., Triticum repens L., currently Elymus repens (L.) Gould by some taxonomists.

GENERAL DESCRIPTION:Erect, sometimes tufted perennial to 1.2 m tall, with extensive rhizomes. Quackgrass is a highly competitive, noxious agricultural weed of cool temperate regions nearly worldwide. It can significantly reduce crop yields, and seed contamination of seed grain crops reduces the value of the harvest. It is comparable to timothy [Phleum pratense L.] as pasture forage or hay. Plants are highly variable with many regional biotypes. Introduced from Eurasia.

SEEDLINGS:Develop rhizomes in the 6-8 leaf stage. (Plants from rhizome buds develop new rhizomes in the 3-4 leaf stage.) Leaf characteristics resemble those of mature plants, except blades are usually 2-3 mm wide and auricles may be undeveloped.

MATURE PLANT:Leaves rolled in bud. Blades 4-30 cm long, 0.2-1.4 cm wide, flat, usually drooping, hairy or glabrous on upper surfaces, glabrous on lower surfaces, with 2 types of veins (faint and strongly ribbed). Ligules membranous, < 1 mm long, minutely fringed. Auricles slender, +/- acute, clasp stem, whitish to violet-tinged. Sheaths open, glabrous or covered with soft, short hairs. Collar broad.

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ROOTS and UNDERGROUND STRUCTURES:Rhizomes numerous, branched, pale yellowish, ~3 mm in diameter, with tough brown sheaths and fibrous roots at nodes, extend horizontally to ~ 1 m, often form a mat-like network, typically ~ 10 cm below the soil surface (to ~ 20 cm deep in cultivated soils). Rhizome tips sharp-pointed, can penetrate hard soils, roots, and tubers. Fragmented rhizomes produce new plants.

SPIKELETS/FLORETS:May-September. Spikes 5-20 cm long. Spikelets sessile, alternate, 1 per node, +/- overlapping, flattened, flat side facing stem, 9-16 mm long, break apart above glumes between florets. Glumes keeled, gradually tapered to a point or tipped with an awn to 4 mm long. Florets 2-9 per spikelet. Lemmas 6-12 mm long, pointed or with an awn to 10 mm long. Often self-incompatible.

HABITAT:Disturbed places, cultivated fields, mountain meadows. Grows on most soil types, including acidic, alkaline, and saline soils.

DISTRIBUTION:Throughout California (except deserts), primarily northern and coastal regions; to Eastern U.S. To 1800 m (6000 ft).

PROPAGATION/PHENOLOGY:Reproduces vegetatively from rhizomes and by seed. Rhizomes tolerate considerable desiccation. New rhizomes grow primarily in summer. New tillers develop spring and fall. Plants commonly produce 20-40 seeds per stem, but range is 15-400. Seed disperses near the parent plant, does not require an afterripening period. Seed germinates in early spring. Fluctuating temperatures stimulate germination, and light is not required. Immature seed (dough stage) can germinate. Seed can remain viable up to 4 years under field conditions. Seedlings can emerge from soil depths to 10 cm.

MANAGEMENT FAVORING/DISCOURAGING SURVIVAL:Repeated cultivation exhausts rhizome food reserves and, along with crop rotation, can control infestations. However, a single disking or cultivation can increase an infestation. Immature seed from cut stems can germinate.

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SIMILAR SPECIES:Tall wheatgrass [Elytrigia elongata (Host) Nevski in part and Elytrigia pontica (Podp.) Holub ssp. pontica in part, synonyms Thinopyrum ponticum (Podp.) Z.-W. Liu & R.-C. Wang, Agropyron elongatum (Host) Beauv.], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski ssp. intermedia, synonym Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] and Russuan wheatgrass [Elytrigia juncea (L.) Nevski ssp. boreali-atlantica (Simonet & Guin.) Hylander, synonym Thinopyrum junceiforme (A. & D. Love) A. Love] are Eurasian perennials that resemble quackgrass. Refer to the table below for comparison. Tall wheatgrass grows in disturbed places throughout California, except for the Northwestern region, to 1600 m (5250 ft). Intermediate wheatgrass grows in open places in the Klamath Ranges, eastern North Coast Ranges, Cascade Range, Sierra Nevada, Transverse Ranges, and desert mountains, to 2100 m (6900 ft). Tall and intermediate wheatgrass are sometimes used to seed rangeland and forestry sites and for erosion control programs.

  rhizomes glumes flower spike axes at maturity blades
quackgrass yes acute to awned at tip remain intact lax, drooping, with > 8 widely spaced faint & conspicuous veins
tall wheatgrass no truncate, weakly keeled remain intact stiff, with veins 8 or less, strongly ribbed
intermediate wheatgrass yes truncate to rounded remain intact stiff, with > 8 veins, strongly ribbed
Russian wheatgrass yes rounded to acute break apart stiff, with veins < 8, strongly ribbed

The ryegrasses (Lolium spp.) lack rhizomes and have spikelets arranged with edges facing the stem and only 1 glume per spikelet.


Prevention: Quackgrass can spread by both vegetative reproduction and by seed. Success of control is increased with early detection and rapid response to new infestations. In agricultural fields, integrated strategies involving tillage, herbicides and crop rotation may limit quackgrass.
In natural areas, fewer options are available and control may be more difficult.

Mechanical: In agricultural fields, generally a minimum of two years of intensive tillage are needed to reduce root reserves and control quackgrass. However, tillage generally fragments and distributes rhizomes which may spread infestations to new areas. Tillage is most successful in dry soils that facilitate dessication of the rhizomes. In the spring, tillage should be repeated when plants regrow to approximately five cm. in height. If soils are to wet for tillage, mowing or close grazing has improved control can be done to prevent seed production. Heavy pasturing or mowing before tilling may enhance control.

Prescribed fire: Repeated, early spring burns may be effective for reducing quackgrass in mixed grasslands in the Central United States, where warm season grasses are a desired component of the plant community. However, early spring burns may be detrimental to the desired plant community in much of California.

Chemical: Selective post-emergence graminicides have been used for quackgrass control. These include fluazifop, sethoxydim, and clethodim. Other effective post-emergence herbicides include nicosulfuron and glyphosate. In natural areas, quackgrass will often be associated with other desirable grasses, which reduces the opportunity for selective control. Spot applications of glyphosate or wick applications have been effective in minimizing non target herbicide injury. Glyphosate can be used selectively if other desirable vegetation is dormant. Fall applications of glyphosate prior to hard frosts have been very effective for quackgrass control.

Chandler, K. C., S. D. Murphy, and C. J. Swanton. 1994. Effect of tillage and glyphosate on control of quackgrass (Elytrigia repens). Weed Technology 8: 450-456.
Davidson, C. G,; Wyse, D. L, and McGraw R L. 1985, Quackgrass Agropyron repens control and establishment of three forage legumes with three selective herbicides. Weed Science 33: 376-380.
Halvorsen, H.H. and R.K. Anderson. 1983. Evaluation of grassland management for wildlife in central Wisconsin. In Kucera, C.L. (ed). Proceedings, 7th North American Prairie Conference, Springfield, MO, University of Missouri, Columbia, MO.
Harker, K.N and P.A. O'Sullivan. 1993. Herbicide comparisons on quackgrass (Elytrigia repens) within different crop competition and tillage conditions. Weed Science. 41(1): 94-99.
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Hamill, A.S. and Zhang Jianhua. 1995. Quackgrass control with glyphosate and SC-0224 in corn and soybean. Canadian Journal of Plant Science 75: 293-299.
Limieux, C., Cloutier, D.C, and Leroux, G.D. 1993. Distribution and survival of quackgrass (Elytrigia repens) rhizome buds. Weed Science. 41(4): 600-606.
Marten, G.C., C.C. Sheaffer, and D.L. Wyese. 1987. Forage nutritive values and palatability of perennial weeds. Agronomy Journal. 74: 899-905.
Stoller, E.W. 1977. Differential cold tolerance of quackgrass and johnsongrass rhizomes. Agronomy Journal. 25(4): 348-351.
Tilman, D. and D. Wedin. 1991. Plant traits and resource reduction for five grasses growing on a nitrogen gradient. Ecology 72 (2): 685-700.
Wedin, D. and. D. Tilman. 1993. Competition among grasses along a nitrogen gradient: initial conditions and mechanisms of competition. Ecological Monographs 63: 199-229.
Werner, P. A. and Rioux. R. R. 1977. The biology of Canadian weeds, Part 24, Agropyron repens. Canadian Journal of Plant Science 57: 905-92.

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