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Cheatgrass - Bromus tectorum
Grass family: Poaceae
Many of the ecosystems that cheatgrass has invaded are seriously
altered, and no longer support the vegetation of the potential natural
community.
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Common Names: Cheatgrass, brome,
downy brome, drooping brome, thatch bromegrass,
broncograss, military grass, downy chess, early chess,
soft chess, wild oats.
Native Range: Europe, the northern rim of Africa,
and southwestern Asia.
Description: A winter annual in
the grass family (Poaceae), bearing many finely hairy,
drooping, yellowishgreen, bristly spikelets in a loose,
much-branched, terminal cluster. It forms small tufts
8-24 inches tall, from a fine fibrous root system. Stems
are erect and slender. Leaf blades are flat and
pubescent. The inflorescence is a dense, drooping
panicle 1 ½ to 8 inches long and is pale green to
purplish in color. Branches are thin, flexuous, and
pubescent. Spikelets are four to seven-flowered and
pubescent or villous. Cheatgrass reproduces by seed that
germinates in the fall, over winters as a seedling, then
flowers in the spring. Seeds have the potential to
remain viable in the seed bank for 2 to 5 years.
Photo: Chris Evans, River to River CWMA, Bugwood.org
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Habitat: It grows on rangelands,
pastures, prairies, fields, waste areas, eroded sites,
and roadsides. It exists in many climatic areas but
primarily in the 6-27 inches precipitation zone. It will
grow in almost any type of soil, however, is most
commonly found on coarse textured soils on B and C
horizons of eroded areas and areas low in nitrogen with
soil temperatures between 2.0-3.5°C and 15°C. Litter
promotes germination and establishment of seedlings.
Distribution: This species is
reported from states shaded on Plants Database map. It
is reported invasive in AZ, CA, CO, CT, HI, ID, NE, NJ,
NV, OR, PA, SD, TN, UT, WA, WV, and WY.
Ecological Impacts: Many of the
ecosystems that cheatgrass has invaded are seriously
altered, and no longer support the vegetation of the
potential natural community. Cheatgrass can maintain
dominance for many years on sites where native
vegetation has been eliminated or severely reduced by
grazing, cultivation, or fire. At maturity the spikelets
break apart; the sharp-pointed, bristly sections can
injure grazing animals by working into the nose, ears,
mouth, or eyes. Spikelets can also cling to hikers’
clothing. It tends to be most invasive in areas
receiving 12 to 22 inches of annual precipitation.
Control and Management:
• Manual- Fire, mowing, grazing, tillage, and
inter-seeding of competitive native plants have all been
shown to reduce populations.
• Chemical- It can be effectively
controlled using any of several readily available
general use herbicides such as glyphosate Follow label
and state requirements.
• Biological control is limited.
Rabbits and mice will feed extensively on this species
as do migratory grasshoppers (Melanoplus sanquinipes).
It is often infected with a head smut (Ustilago
bulleta Berk.) that, when severe, may reduce seed
yield. Some research has been conducted on pink snow
mold (Fusarium nivale) as a biological control
agent, but information has yet to be released.
Photo: Leslie J. Mehrhoff,
University of Connecticut, Bugwood.org
Reproductive /
Dispersal Mechanisms
Cheatgrass
reproduces by seeds
that are dispersed
by gravity, wind and
other mechanical
means. The awns on
each of its florets
are barbed and
capable of piercing
and adhering to fur
and clothing. This
promotes the seed's
dispersal through
"hitching rides" on
animals, people and
even vehicles.
Bromus tectorum is a
native of
Mediterranean
Europe. It gets the
name "tectorum",
which means roof,
from its historical
penchant for growing
on thatched roofs.
It is currently
present in all fifty
of the United
States, all of the
Canadian provinces
and parts of Mexico.
It is much more
abundant in the
western U.S. and
Canada, notably in
regions where the
annual rainfall is
between 15 and 55 cm
(5.9-21.7 in.). It
is most problematic
on heavily grazed
rangeland and
regions where winter
wheat is grown.
Bromus tectorum is
on the noxious weed
lists of at least 35
states. In New
England, it is found
mostly along
roadsides and in
disturbed areas.
Bromus tectorum
has the ability to
draw down soil
moisture and
nutrients to very
low levels, making
it difficult for
other species to
compete. An
increased cycle of
fires favors annual
species at the
expense of many
perennials. Due to
its tendency to
mature early and
then dry out, B.
tectorum gains a
competitive
advantage through
the promotion of
fire. Though very
important to
Bromus tectorum's
success out West,
this fire dynamic
has not helped it in
New England.
Bromus tectorum
is a serious
agricultural weed in
the western U.S.
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Prevention
Despite successful
efforts to control downy brome in croplands --
infested rangelands, pastures, roadsides, and
waste areas throughout Montana provide a
continuing source of downy brome seed for
reinvasion of winter wheat crops. Seed spread
is mainly through contaminated grain, hay,
straw, manure and farm machinery. The long awn
attached to the seed helps it stick to animal
fur, as well.
To prevent initial
infestation in cultivated land, ensure that any
seed purchased is certified free of downy brome
and thoroughly clean equipment, especially
swathers and combines.
Four main reasons
are cited as to why downy brome has become more
of a major problem in cultivated land.
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Farmers are
re-cropping more, thereby not allowing for
the opportunity to break up the downy brome
life cycle.
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The shorter
wheat varieties used today allow more light
to penetrate the crop canopy, making downy
brome more competitive.
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More
fertilizer is used each year giving downy
brome a competitive edge.
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Farmers rarely
use the mold-board plow and are instead
using variations of either stubble/mulch
tillage or no tillage at all. The chisel
plow doesn’t invert soil, and as a result,
downy brome seed is no longer buried
deeply. In no-till farming, downy brome
seed remains on the soil surface which is
the preferred environment of this plant
since it is a surface germinator. It
thrives under no-till production. Shallow
burial, or surface germination, is the ideal
germination environment for downy brome
(Wright and Fay 1995).
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Photo: Richard Old, XID Services, Inc., Bugwood.org
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