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Managing ALS-Resistant Palmer Amaranth in Peanuts

Managing ALS-Resistant Palmer Amaranth in Peanuts. Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia. What does ALS mean?. Acetolactate synthase (ALS) Acetohydroxyacid synthase (AHAS) chloroplast enzyme needed to form certain amino acids

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Managing ALS-Resistant Palmer Amaranth in Peanuts

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  1. Managing ALS-Resistant Palmer Amaranth in Peanuts Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia

  2. 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

  3. 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 Commonly Used ALS Herbicides

  4. 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)

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

  6. Metolachlor Mysteries

  7. GR-Pigweed/Soybean Test – II (2006)7 WAP RUWM (POST) Valor @ 2 oz/A (PRE) RUWM (POST) Untreated

  8. 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!!

  9. Valor Injury in Peanut

  10. 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)

  11. How/Why do we let pigweeds get this big????

  12. Will these herbicides control large pigweeds?

  13. Cobra 2EC @ 12.5 ozs/A + COC @ 1% v/v applied to 17” tall pigweed 4 DAT 1 DAT 7 DAT 16 DAT

  14. 2,4-DB/Cobra Test – 2006 2,4-DB 1.75SL @ 1.1 pt/A + Agrioil @ 1% v/v (POST) fb Cobra 2EC @ 12.5 oz/A Agrioil @ 1% v/v POST2 Untreated Cobra 2EC @ 12.5 oz/A Agrioil @ 1% v/v POST POST: June 5 (17” tall pigweed) POST2: June 9 Photos taken 24 days after POST application

  15. Does Cobra reduce yields??

  16. 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 @ 12.5 ozs/A Agrioil @ 1% v/v Applied 30 DAP

  17. 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

  18. Where do Cadre and Strongarm fit in? • Effective on many other weeds • Cadre is the only herbicide that will control purple nutsedge

  19. Cadre @ 4 ozs/A + 2,4-DB @ 1.1 pt/A + COC @ 1% v/v – 34 DAT Applied to 17” tall pigweed

  20. Cultivation(no weeds are steel-resistant!!!) • Time • Diesel fuel prices • Strip-tillage • Twin rows • White mold

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

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

  23. What if we do not control Palmer amaranth?

  24. www.gaweed.com

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