Managing ALSResistant Palmer Amaranth in Peanuts

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Managing ALS-Resistant Palmer Amaranth in Peanuts

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

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What does ALS mean?

• Acetolactate synthase (ALS)
• Acetohydroxyacid synthase (AHAS)
• chloroplast enzyme needed to form certain amino
  acids
• Valine, leucine, isoleucine
• Herbicide families
• Imidazolinones
• Sulfonylureas
• Sulfonanalides
• benzoates

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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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ALS-Resistant Palmer Amaranth Survey
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Managing ALS-Resistant Palmer Amaranth in Peanuts

• Weed-free at planting
• Preemergence herbicides
• Prowl or Sonalan on every acre ?
• Postemergence herbicides
• Cultivation
• Harvest Aids
• Rope-wick applications
• Mowing
• Other tactics
• Crop rotation with corn (atrazine)

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Preemergence Herbicides

• Valor
• Dual Magnum
• Generic Metolachlors
• Outlook/Propel
• What about..
• Reflex
• Goal
• Solicam
• activation

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Metolachlor Mysteries
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GR-Pigweed/Soybean Test II (2006)7 WAP
Valor _at_ 2 oz/A (PRE) RUWM (POST)
RUWM (POST)
Untreated
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Valor in Peanuts - The Bottom Line

• Plant at least 1.5 deep and apply within 2 days
  of planting
• Injury will occur if heavy rainfall occurs from
  cracking until 2 WAC
• peanut yield should not be reduced if stand is
  not lost
• hose and nozzle clean-out very important!!!!!
• except this or do not use it
• Glyphosate was developed as an industrial
  cleaner!!

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Valor Injury in Peanut
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Postemergence Herbicides

• Timing, timing, timing
• 16 in 1 week
• Paraquat
• G-Inteon
• Firestorm
• 15 GPA
• flat fan nozzles
• tractor speed
• Cobra
• Ultra Blazer
• Storm
• 2,4-DB

Cobra, Storm, Ultra Blazer, Valor have the same
mode of action (PPO inhibitors)
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How/Why do we let pigweeds get this big????
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Will these herbicides control large pigweeds?
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Cobra 2EC _at_ 12.5 ozs/A COC _at_ 1 v/v applied to
17 tall pigweed
4 DAT
1 DAT
7 DAT
16 DAT
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2,4-DB/Cobra Test 2006
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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Does Cobra reduce yields??
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Peanut (GA Green) Response to Cobra78 DAP - 2006
4003 lbs/A Tifton 4319 lbs/A - Plains
3556 lbs/A Tifton 4450 lbs/A - Plains
Untreated
Cobra _at_ 12.5 ozs/A Agrioil _at_ 1 v/v Applied 30 DAP
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PPO Resistance???

• PPO or Protox
• Protoporphyrinogen oxidase
• Enzyme found in chloroplast and mitochondria
• 3 species worldwide
• Common waterhemp
• Kansas (2001)
• Illinois (2002)
• Common ragweed
• Delaware (2005)
• Wild poinsettia
• Brazil (2004)\
• Ultra Blazer, Cobra, Goal, Reflex, Ronstar,
  Resource, Aim, Valor, Storm, Spartan

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Where do Cadre and Strongarm fit in?

• Effective on many other weeds
• Cadre is the only herbicide that will control
  purple nutsedge

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Cadre _at_ 4 ozs/A 2,4-DB _at_ 1.1 pt/A COC _at_ 1
v/v 34 DAT
Applied to 17 tall pigweed
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Cultivation(no weeds are steel-resistant!!!)

• Time
• Diesel fuel prices
• Strip-tillage
• Twin rows
• White mold

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Rope-wick Applicators

• glyphosate is labeled for wiper applications in
  row middles
• 33-50 solution
• Opposite directions
• 5 MPH or less
• GR-pigweed concerns??

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Mowing

• Weed/peanut height differential
• Digging and harvest aid
• Flail mower better than rotary mower
• diesel fuel prices
• Time???

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What if we do not control Palmer amaranth?
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