Managing Palmer Amaranth Peanuts Field Corn Soybeans

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Managing Palmer AmaranthPeanutsField Corn
Soybeans

• Eric P. Prostko
• Extension Weed Specialist
• Dept. of Crop Soil Sciences
• The University of Georgia

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Managing Palmer Amaranth

• Know your enemy
• Resistant or not??
• ALS or GR
• Residual herbicide
• Activation (irrigation or incorporation)
• Timely POSTs
• Avoid overusing PPOs

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Why Palmer Amaranth?

• 38 species of Amaranthus in U.S.
• 27 species found in SE
• grows faster than other pigweeds (1-2 per day!!)
• more competitive than other pigweeds
• prolific seed producer
• Up to 1,000,000 seeds/plant
• 9-12 WAE
• 2 generations/year
• herbicide tolerance

SWSS Weed ID Guide
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Palmer Amaranth is very competitive!!!

• Yield loss caused by 1 plant/meter of row
• Soybean (27)
• Peanut (28)
• Corn (32)
• Cotton (48)

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GA Confirmed Glyphosate-Resistant Palmer Sites
2005
2006
Current Testing 2007
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Commonly Used ALS Herbicides

• Accent
• Ally/Cimarron
• Beacon
• Beyond
• Cadre
• Classic
• Envoke
• Exceed
• Express
• Finesse
• FirstRate

• Glean
• Harmony Extra
• Maverick Pro
• Osprey
• Peak
• Permit
• Pursuit
• Python
• Scepter
• Staple
• Strongarm

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GA Confirmed ALS-Resistant Palmer Sites
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Use a residual herbicide!!!!

• Corn atrazine, Dual Magnum/Generics, Callisto,
  Prowl
• Atrazine resistance in Macon Co (2007)
• Peanut Valor, Dual Magnum/Generics, Prowl,
  Sonalan
• Soybean Valor, Valor XLT, Reflex, Canopy,
  Sencor, Dual Magnum/Generics, Boundary, Prefix,
  Treflan, Prowl

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Residual Herbicides Must Be Activated!!!!!!

• Rainfall
• Irrigation
• Herbicide incorporation
• Conventional tillage
• Dryland fields
• No chance of rain
• will help but not a guarantee
• 2X, angle
• Some herbicides should not be incorporated
• Valor

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Things You Do Not Often See in Georgia
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PPO Resistance???

• PPO or Protox
• Protoporphyrinogen oxidase
• Enzyme found in chloroplast and mitochondria
• 3 species worldwide
• Common waterhemp
• Common ragweed
• Wild poinsettia
• Many common herbicides have this mode of action!!
• Ultra Blazer, Cobra, Goal, Reflex, Ronstar,
  Resource, Aim, Valor, Storm, Spartan, ET

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Herbicide Modes of Action Info

• New Table in 2008 Pest Control Handbook
• MOAs listed in crop sections
• www.gaweed.com

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Field Trial Results
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Peanuts
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Palmer Amaranth Control in PeanutsMacon County,
GA 2007 (38 DAT)
NTC
Valor SX 51WG _at_ 3 oz/A
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Palmer Amaranth Control in PeanutsMacon County,
GA 2007 (38 DAT)
Dual Magnum 7.62EC _at_ 1 pt/A
NTC
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Palmer Amaranth Control in Peanut with PRE
Herbicides
Valor _at_ 3 oz/A Dual Magnum _at_ 1 pt/A Stalwart _at_ 1
pt/A Outlook _at_ 1 pt/A
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2,4-DB fb Cobra or Ultra Blazer?????
2,4-DB 1.75SL _at_ 1.1 pt/A Agrioil _at_ 1 v/v
(POST) fb Cobra 2EC _at_ 12.5 oz/A Agrioil _at_ 1
v/v POST2
Untreated
Cobra 2EC _at_ 12.5 oz/A Agrioil _at_ 1 v/v POST
POST June 5 (17 tall pigweed) POST2 June
9 Photos taken 24 days after POST application
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Field Corn
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GR-Palmer Amaranth Control in Field CornMay 31,
2007 (38 DAP)
Roundup Original Max (22 oz/A) Atrazine (2
qt/A) Prowl H20 (2.1 pt/A) EPOST (18 DAP)
NTC
CN-07-07
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GR-Palmer Amaranth Control in Field Corn May 31,
2007 (38 DAP)
NTC
Halex GT 4.38SC _at_ 4 pt/A 80/20 _at_ 0.25 v/v AMS _at_
8.5 lbs/100 gals EPOST (18 DAP)
CN-07-07
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Palmer Amaranth Control in Sorghum-Sudangrass
Silage
NTC
2,4-D amine _at_ 1 pt/A (27 DAT)
GS-01-07
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Soybeans
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GR-Palmer Amaranth Control in Soybean 2007 (83
DAT)
Untreated
Boundary 6.5EC _at_ 1.8 pt/A
SB-01-07
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GR-Palmer Amaranth Control in Soybean 2007 (83
DAT)
Untreated
Prefix 5.2EC _at_ 2.03 pt/A
SB-01-07
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GR-Palmer Amaranth Control in Soybean 2007 (77
DAT)
Untreated
Valor SX 51WG _at_ 3 oz/A
SB-02-07
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Harmony GT XP or Harmony SG

• Harmony GT XP (75)
• GT grass-tank mix
• XP extruded pellet
• 1/12 oz/A (1.17)
• Harmony SG (50)
• SG soluble granules
• 1/8 oz/A
• 1st trifoliate until 60 days before harvest
• tank-mix with glyphosate
• ALS inhibitor
• up to 12 tall pigweed?????
• Soybean injury

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Managing Palmer Amaranth

• Know your enemy
• Resistant or not??
• ALS or GR
• Residual herbicide
• Timely POSTs
• Avoid overusing PPOs

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www.gaweed.com