repens (L.) Nevski][AGRRE][CDFA list: B] Photographs Map of
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.
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.
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.
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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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.
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.
cultivated fields, mountain meadows. Grows on most soil types,
including acidic, alkaline, and saline soils.
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.
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.
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.
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
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
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.
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