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Cheatgrass: Biology,
Ecology, and Management
Jane Mangold
Extension Invasive Plant Specialist
Department of Land Resources and
Environmental Sciences
Cheatgrass (Bromus tectorum)
Annual Large and open
panicle Drooping ½ inch awns
Japanese brome (B. japonicus)
Large and open, heavy panicle
Drooping < ½ inch awns
Impacts Across Montana
Rangeland
CRP
Crops
56.7 million acres in western statesExpanding by 14% per year
-Duncan et al. 2004
Cheatgrass Origin and Distribution
Native of southwestern Asia Introduced to North America in several
independent events• Contaminated seed• Ship ballasts
Problematic in western U.S. and Canada and northern Mexico
Weedy Characteristics: Winter Annual
Germinates/emerges in fall Resumes growth in early spring Produces seed May-June Plant dies, seed dormant until fall
Cheatgrass Produces Lots of Seed
400 – 4,000 seeds/plant Short seed life (2-3 years) Dispersed by humans, animals, wind,
machinery, contaminated straw/hay, etc.
Cheatgrass Seeds Germinate Quickly
Days to 25% germination
Species Days
Cheatgrass 3.8a
Medusahead 5.5b
Smooth brome 6.6c
Crested wheatgrass 6.9cd
Siberian wheatgrass 7.3d
Bluebunch wheatgrass 8.1e
Days to 25% germination after exposure to freezing temperatures (Jan. 31-Feb. 15)
Days
***
***
5.5b
4.3a
4.9a
6.2a
***Cheatgrass and medusahead had begun to germinate in the field by February 10
Wilson et al. 1974. J. Range Manage. 27(2):120-122
Cheatgrass Grows Fast
Arredondo et al. 1998. J. Range Manage. 51(5):584-589
Cheatgrass Adjusts to Local Conditions
Photo courtesy of Lori Ziegenhagen, USDA-ARS
Photo courtesy of Lori Ziegenhagen, USDA-ARS
Cheatgrass
Bluebunch wheatgrass
1
1
2
2
Impacts
• Reduces plant diversity• Reduces forage and crop yield
and quality• Alters fire regimes• Ruins my socks!
Cheatgrass Alters Fire RegimesIncrease in
quantity and
continuity of fuel
Larger and more
frequent fires
Perennial species
unable to recover
Further increase in cheatgrass
Cheatgrass Management
Target cheatgrass in spring and fall
X
Prevent seed development!Deplete seed bank!
Control Method Effectiveness
Prevention
Chemical
Revegetation
Mechanical
Grazing/Mowing
Biocontrol
Prescribed Fire
Prevention EDRR Maintain healthy, competitive plant
community• Cheatgrass increases with removal of native
perennial grasses and forbs (which can occur as a result of over-grazing)
Minimize disturbance Limit spread of seeds
Chemical Control--Some Herbicide Tolerance
Photo by Ed Davis, MSU
Non-sprayed control
Sprayed, but cheatgrass only
suppressed
ChemicalHerbicide Active Ingredient
Trade NameProduct per Acre Application Timing
Glyphosate Roundup Pro
6 to 12 ounces Early spring while other grasses are still dormant; after emergence in fall
Targeting Cheatgrass with Glyphosate
Sprayed on May 11, 2009 Non-sprayed control
3 sites (Madison and Ruby Valleys)3 reps/siteSprayed at 0, 6, 8, 10, or 12 oz. Roundup/ASampled June 16-18, 2009
Targeting Cheatgrass with Glyphosate
Sprayed on May 11, 2009 Non-sprayed control
Nu
mb
er o
f p
lan
ts/0
.1m
2
Data pooled across 3 sites
Chemical ControlHerbicide Active Ingredient
Trade NameProduct per Acre Application Timing
Glyphosate Roundup Pro
6 to 12 ounces Early spring prior while other grasses are still dormant
Imazapic + glyphosate Journey
16 to 32 ounces Late summer to early fall before emergence and prior to planting desirable species
Imazapic Plateau
2 to 12 ounces Late summer to early fall before emergence and prior to planting desirable species
Sulfometuron methyl + chlorsulfuronLandmark
0.75 to 2.25 ounces Spring or fall application followed by planting desirable species in fall (at least 3-6 months after spraying)
RimsulfuronMatrix
2 to 4 ounces Spring or fall application followed by planting desirable species in fall (at least 7 months after spraying)
Effect of Imazapic on Annual Grasses*
Rate(oz/ac)
% Control 30
DAT
% Control 60 DAT
Density 60 DAT(plants/m2)
Biomass 60 DAT(g/m2)
0 0a 0a 532a 8a
4 70b 67b 179b 23a
8 75c 80b 164b 16a
*22% cheatgrass, 15% annual bluegrass, 15% medusahead
Shinn and Thill. 2002. Weed Tech. 16(2): 366-370
Revegetation
Seeding desirable, competitive vegetation is necessary if very little desirable vegetation is remaining (<20-30% cover)
Must control cheatgrass• Multiple years of control prior to revegetation
Competitive Effects of Seeded GrassesSeeding
TreatmentPerennial Grass Biomass (kg/ha)
Cheatgrass Biomass (kg/ha)
% Reduction
Critana thickspike wheatgrass
792 913 32
Bozoisky Russian wildrye
900 737 45
Sodar streambank wheatgrass
1135 207 85
Luna pubescent wheatgrass
1714 0 100
Hycrest crested wheatgrass
1596 124 91
Unseeded control --- 1337
Whitson and Koch. 1998. Weed Tech. 12(2): 391-396
Assisted Succession
Restoration of weed-infested rangeland may require multiple steps
Cheatgrass/ annual forbs
Introduced, competitive grass
Native vegetation
Disturbed soil typically increases cheatgrass Multiple treatments or follow up with
herbicide/grazing/mowing
disked strips—notice brown, cured cheatgrass
Mechanical Control
Grazing
Cattle, Sheep, and Goats• Spring
• Accessible but not yet producing seed• >2 defoliations each spring• >2 consecutive years
• Winter • Reduce mulch accumulation• Energy and protein supplements required
Graze/mow before plants start to turn purple!
Grazing Scenario
Dominated by cheatgrassDevoid of perennial vegetation
Dominated by perennialsCheatgrass present
1) 2)
In which scenario will be easier to manage cheatgrass?
Biocontrol
None currently available Researching potential for soil and seed fungi • Soil fungus Pyrenophora semeniperda
• “Black fingers of death”• Kills cheatgrass seeds in soil
• Seed fungus Ustilaga bullata• Infects germinating seeds• Plant grows to maturity but doesn’t produce seeds
Prescribed Fire
Hot fire will destroy seeds on soil surface, in the litter, and on the plant• Reduce germinable seeds by 98-100%
Seeds buried in the soil will be protected Fire can reduce litter accumulation
Prescribed Fire
Risky due to timing• Typically not enough fuel to carry fire at most
appropriate time• Damage perennial, desirable vegetation• Potential for fire to get out of control
More promising for Japanese brome than cheatgrass
Integrated Cheatgrass Management
Prevention Integrate tools to decrease seed production
and seed bank over time Revegetation is imperative where very little
desirable vegetation is remaining Persistence and intelligence—use your
hands and your head! More research is necessary in Montana
