integrated weed management— managing for healthy plant communities jane mangold extension invasive...
TRANSCRIPT
Integrated Weed Management—Managing for Healthy Plant
Communities
Jane Mangold
Extension Invasive Plant Specialist
Department of Land Resources and Environmental Sciences
What we’ll cover
1) Integrated Weed Management (IWM)• What is IWM?• Ecological framework for IWM
2) Healthy plant communities• Healthy plant community defined• Managing for a healthy plant community
3) Integrated management of cheatgrass
Integrated Weed ManagementBegin with the end in mind. . .
Kill the weed—Yes, but not the whole story Healthy plant community that meets
management objectives
whitetop (hoary cress) infestation
Weed Management
Herb
icides
Multiple classes of livestock
Hand pulling
Revegetation
BiocontrolMowing
Prevention
Prescribed fire
Integrated Weed Management
Integrated Weed Management
Control strategies that include a combination of methods to reduce weed populations to an acceptable level
Replace one big hammer with “many little hammers” (Liebman and Gallandt 1997)
Traditional Management
Weed LifeCycle
Biocontrol
Revegetation
Tilling/diskingMowing
Herbicides
Grazing
Fire
Hand-pulling
Fertilization
Prevention
Irrigation
Future Management
Weed Life Cycle
Biocontrol
Revegetation
Tilling/disking
Mowing
Herbicides
Grazing
Fire
Hand-pulling
FertilizationPrevention
Irrigation
Plant CommunityDynamics
Desired Vegetation
Site Availability
Species Performance
Species Availability
Plant Community Undesired State
Plant Community Desired State
Framework for IWM
Managing Plant Communities
Controlling Site Availability
Controlled Site
Availability
Controlled Species
Performance
Controlled Species
Availability
Plant Community Undesired State
Plant Community Desired StateBiocontrol
Revegetation
Tilling/disking
Mowing
Herbicides
Grazing
Fire
Hand-pulling
Fertilization
Prevention
Irrigation
Healthy Plant Communities
Healthy Plant Community = Diverse
DiversityMultiple speciesMultiple functional groupsUtilizes plant resources (water, nutrients, light) through space and time
Functional Groups
1. Occupy similar niche
2. Use resources similarly (temporal and spatial)
3. Similar growth forms
4. Similar life histories
5. Similar morphology/root structure
What functional groups do you see?
Functional groups influence spotted knapweed invasion
(Pokorny et al. 2005)
Diversity in Your Pasture
Management objective:• Grass production
• Variety of species that mature at different times of the season
• Different growth habits (bunch vs. sod-forming)
bluebunch wheatgrasswestern wheatgrass
Sandberg’s bluegrass
Healthy Plant Community = Productive
Productive Functional Group Limits Invasion of Annual Grass
(James et al. 2008)
Healthy Plant Community = Diverse and Productive
+. . .and meets management objectives
Plant Biology 101
CO2
CO2 + H2O + photons (energy) C6H12O6 (glucose) + O2
Defoliation
Repeated Defoliation
Best Management PracticesSite Availability
Limit intensity and frequency of disturbance Weeds like disturbed areas! • Do not overgraze• Vary grazing rotations• Minimize activities that disturb the soil• Monitor disturbed areas• Killing weed may open up site for re-invasion
• Consider species availability and species performance
Best Management PracticesSpecies Availability
Prevent weeds from producing seed Prevent weed seed dispersal• Driving through infestations• Livestock• Weed-free seed and forage
If less than 20-30% cover of desirable species, revegetation is likely necessary• Diverse and productive seed mixes• Easily established• Bridge species
Best Management PracticesSpecies Performance
Target weed while promoting desirable vegetation• Like species repel like species• High productivity reduces invasion
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Best Management PracticesSpecies Performance
Use appropriate control method at appropriate time, especially herbicides• Limit non-target effects• Maximize efficacy• Spot-treat
Best Management PracticesSpecies Performance
Limit resource availability• Fertilization typically not necessary
0.6 ± 0.13 ppm NO3-N ≤ 0.05 ppm NO3-N
Spotted knapweed Bluebunch wheatgrass
(Krueger-Mangold et al. 2006)
Integrated Management of Cheatgrass
Cheatgrass (Bromus tectorum)
Annual Large and open panicle Drooping ½ inch awns Turns reddish-purple, then
brown
Winter Annual Germinates/emerges in fall Seedlings resume growth in early spring Produces seed May-June Plant dies, seed dormant until fall Seeds remain viable 2-3 years
Cheatgrass Management
Target cheatgrass in spring and/or fall
X
Prevent seed development!Deplete seed bank!
Control Method Effectiveness
Prevention
Chemical
Grazing
Revegetation
Mechanical
Biocontrol
Prescribed Fire
Prevention Locate and manage small infestations 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 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, early post-emergence and prior to planting desirable species
Imazapic Plateau
2 to 12 ounces Late summer to early fall, early post- 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 (3-6 months after)
RimsulfuronMatrix
2 to 4 ounces Spring or fall application followed by planting desirable species in fall (7 months after)
Controlling Cheatgrass Performance 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
Sprayed on May 11, 2009 Non-sprayed control
Nu
mb
er o
f p
lan
ts/0
.1m
2
Data pooled across 3 sites
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!
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
Revegetation Species for SW MontanaNative Introduced
Slender wheatgrass Russian wildrye
Thickspike wheatgrass Pubescent wheatgrass
Streambank wheatgrass Sheep fescue
Bottlebrush squirreltail Perennial ryegrass
Sandberg bluegrass Tall wheatgrass
Big bluegrass Crested wheatgrass
Disturbed soil typically increases cheatgrass Multiple treatments or follow up with
herbicide/grazing/mowing
disked strips—notice brown, cured cheatgrass
Mechanical Control
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 Cheatgrass may increase with fire if not
integrated with other methods Hot fire will destroy seeds• Seeds buried in the soil will be protected
Fire can reduce litter accumulation Follow-up with grazing, herbicide application,
and/or revegetation
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!
Thank you! Questions. . .