Downy brome and Medusahead Control in Rangelands 1 with Rimsulfuron

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Downy brome and MedusaheadControl in Rangelands
(1) with Rimsulfuron

• Ronnie G. Turner, Jerry R. Pitts,
• Mike T. Edwards, Norman D. McKinley,
• C. William Kral, Craig M. Alford, John D. Cantlon
• DuPont Crop Protection
• 8295 Tournament Drive, Suite 300
• Memphis, TN 38125
• (1) Rimsulfuron is not currently registered in
  Rangelands

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Downy BromeBromus tectorumPhotos Steve Dewey,
Utah State University Chris Evans, University of
Georgia
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Downy Bromeaka cheatgrass

• Invasive grass - Native of southern Europe
• Now Infests 100 Million Acres in US
• Quick Invader of heavily grazed rangeland, burned
  areas, and other disturbed sites
• Winter Annual
• Dev large root system fall to spring robs
  moisture
• Deters native grass seedlings reduces population
• Dries down quickly by early summer extended
  wildfire hazard
• Early/often wildfires prevent native grass/sage
  regeneration which can decrease wildlife habitat
• Little Grazing Value
• Bad taste pulls up easily
• Sharp seed pods injure mouths of grazing animals

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MEDUSAHEADTaeniatherum caput-medusaePhotos
Steve Dewey, Utah State University Bugwood web
site
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MEDUSAHEAD

• Invasive grass Native of Eurasia
• Infests large areas of PNW, CA
• Usually more prevalent on Clay soils, but has
  also been found on sandy soils
• Winter Annual
• Repro by seed matures 2-4 wks later vs. other
  annual grasses
• Fibrous root system develops faster than downy
  brome
• Depletes upper soil moisture early season
  (reduces germination potential for native grass
  seed)
• Dead stems decompose slowly forming dense mats
  increased fire potential
• Little Grazing Value
• High silica content (unpalatable) stiff awns,
  hard florets can injure eyes, mouth of cattle

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Rimsulfuron

• DuPont Sufonylurea Herbicide
• Inhibits acetolactate synthase (ALS)
• Registered for Use in Field Corn, Potatoes,
  Tomatoes registration pending in Fruit, Nut,
  Vine crops, and future uses expected in Roadsides
  and Rangelands
• Pre and Post activity on Grasses and Broadleaf
  Weeds
• Root and Foliar uptake moves in xylem and phloem
• Behavior in Water and Soil
• At 25C, half-life in water at 4.6 (pH 5) to 0.3
  (pH 9) days
• Across 4 soil types, half-life ranged 1.7 to 4.3
  days at 86F (30C)
• In Aqueous Solutions, half-life at 68F (20C)
  and pH 7 24 days at 50F(10C), pH 7 half-life
  at 144 days

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Rimsulfuron Downy BromeApplication Timing
late Oct early Dec
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Rimsulfuron Telar Application Timing late
Oct early Dec
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Rimsulfuron MedusaheadApplication Timing late
Oct early Dec
No. Tests ( )
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Rimsulfuron Telar Application Timing late
Oct early Dec
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Downy Brome Rangeland Trial

• Location Pleasanton, NE
• Application Date 20-Nov-2005
• Application Equipment CO2 Sprayer
• Application Volume 14 gal/ac
• Weed Stage Downy Brome, 2 to 4 tillers
• Crop Stage Western Wheatgrass 2 to 4
• Evaluation 230 DAT (days after treatment)

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Downy Brome ( 230 DAT )Rim 0.75 oz ai/A Surf
UTC
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Downy Brome ( 230 DAT )Rim 1 oz ai/A Surf
UTC
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Downy Brome ( 230 DAT )Landmark 1.125 oz ai/A
Surf UTC
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Downy Brome ( 230 DAT )Plateau 1.88 oz ai/A
Surf UTC
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Medusahead Rangeland Trial

• Location Boise, ID
• Application Date 13-Oct-2005
• Application Equipment CO2 Sprayer
• Application Volume 20 gal/acre
• Plot Size 10 X 30 X 3 Reps
• Pest Stage at Application
• Senescent Medusahead Early Germination

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Medusahead (195 DAT ) Rimsulfuron 1 oz ai/A
Surf UTC
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Medusahead (195 DAT ) Rim 1 Telar .375 oz
ai/A Surf UTC
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Medusahead (195 DAT ) Landmark 1.125 oz ai/A
Surf UTC
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Medusahead (195 DAT ) Plateau 1.88 oz ai/A
Surf UTC
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Rimsulfuron SummaryIn these trials,

• Rimsulfuron provided excellent control of Downy
  brome
• Rimsulfuron provided good control of Medusahead
  rye (fewer tests)
• Install further tests in Fall 2006 especially for
  Medusahead
• Install Plant Back trials to evaluate Native
  Grass tolerance following Rim applications
• Field Trails and University Field Station - NCal

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THANK YOU !!

• QUESTIONS ???

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Additional Slides - References
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Cheatgrass / MedusaheadReferences (web sites)

• Cheatgrass
• http//extension.usu.edu/rangeplants/Grasses/cheat
  grass.htm
• www.pnl.gov/pals/resource_cards/cheatgrass.stm
• www.usgs.gov/invasive_species/plw/prescribedfire.h
  tml
• A homeowners guide to cheatgrass. Jay davison, Ed
  Smith, Cooperative Extension, University of
  Nevada, Reno
• www.explorebiodiversity.com/problem_plants/species
  /Cheatgrass.htm
• www.wy.blm.gov/cheatgrass/index.htm

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Cheatgrass / MedusaheadReferences (web sites)

• Medusahead
• www.cdfa.ca.gov/phpps/ipc/weedinfo/taeniatherum-ca
  put-medusae.htm
• http//californiarangeland.ucdavis.edu/water_quali
  ty/MEDUSA.HTM
• www.yolorcd.org/weeds/medusahead.shtml
• www.oregon.gov/ODA/PLANT/WEEDS/profile_medusaheadr
  ye.shtml
• www.cdfa.ca.gov/wma

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