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Strategies for Managing Herbicide Resistant Palmer Amaranth in Soybean - 2012. Eric P. Prostko Professor and Extension Weed Specialist Dept. Crop & Soil Sciences. Herbicide-Resistant Palmer Amaranth in GA. ALS (2000) Glyphosate (2005) Atrazine (2009) ALS + GLY (2009)
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Strategies for Managing Herbicide Resistant Palmer Amaranth in Soybean - 2012 Eric P. Prostko Professor and Extension Weed Specialist Dept. Crop & Soil Sciences
Herbicide-Resistant Palmer Amaranth in GA • ALS (2000) • Glyphosate (2005) • Atrazine (2009) • ALS + GLY (2009) • DNA + ALS + GLY (2010) • ALS + GLY + ATZ (2011)
Important Things We Know About Palmer Amaranth • Well-adapted to Georgia! • Native to Sonoran desert • Separate male and female plants • Lots of seed!!!! • 400,000 – 500,000/female plant • Seed do not last long in soil • 20% germ after 30 months • Seed do not emerge from deep depths (≥ 3-4”) • Seed need light to germinate • Resistance trait moves in pollen • At least 1000 feet!!
Palmer AmaranthVery ompetitive • 1 Palmer amaranth plant per meter (3.3 ft) of row can reduce soybean yield by 32%.
Pigweed Control is not impossible!!!! Common Reasons for Failure: 1) did not start clean 2) did not use a residual 3) residual did not get activated 4) POST applications are too late 5) short arms and deep pockets
Many pigweed problems are due to weeds already up at planting!
Palmer Amaranth Growth 22 days after starting clean June 22, 2011 Attapulgus, GA
Dryland Production SystemsA Difficult Challenge! • Growers need to think about mechanical herbicide incorporation • Will help but not a guarantee • Success will depend upon…… • operator • implement • soil conditions
Tillage and Pigweed Bottom Plow Chisel Plow Source: Twiggs Co., April 22, 2010
Extreme Cover Crops 1 2 3 4
Row Spacing Washington County 2009
Herbicides for Pigweed Control in Soybeans • Residual Herbicides • Authority MTZ, Authority XL, Canopy/Cloak, Boundary, Valor, Valor XLT, Prefix, Dual Magnum/Generics, Tricor, Prowl, Intrro, Treflan, Envive, Warrant • Postemergence • Reflex/Dawn, Prefix, Cobra, Ultra Blazer, Flexstar GT, Harmony (ALS?), Ignite (LL soybeans)
Consider metribuzin on soybean? • Not a PPO • Not a PPO • Good on pigweed • Can be applied PPI • Issues • soil texture, OM, pH • Varieties • Rotations • Company support • Lack of incentive at dealer level • Cost/A TriCor 75DF Metribuzin 75DF
Palmer Amaranth Control in Soybeans - 2011 NTC Valor SX 51WG @ 2 oz/A SB-13-2011 June 23, 2011 30 DAP
Palmer Amaranth Control in Soybeans - 2011 NTC Boundary 6.5EC @ 1.5 pt/A SB-13-2011 June 23, 2011 30 DAP
Liberty-Link Soybeans - 2011 NTC Ignite @ 29 oz/A (EPOST) Warrant @ 3 pt/A (EPOST) AMS Xtra @ 2.5% v/v (EPOST) Prefix @ 2.5 pt/A (PRE) Ignite @ 29 oz/A (MPOST) AMS Xtra @ 2.5% v/v (MPOST) SB-04-11 July 20 58 DAP
On the Horizon Zidua Anthem Fierce Enlist Soybean Enhanced tolerance to 2,4-D Stacked with glyphosate 2015? Dicamba Resistant Soybeans Monsanto/BASF Stacked with glyphosate 2013?
Zidua 85WG • Pyroxasulfone • Residual control of annual grasses and certain broadleaf weeds including pigweed • Same MOA as Dual or Warrant but used at lower rates • Use rate: 1-2 oz/A
Palmer Amaranth Control in Soybeans - 2011 NTC Zidua 85WG @ 2 oz/A SB-13-2011 June 23, 2011 30 DAP
Fierce 76WDG • February 2012 (?) • Valor (33.5%) + Pyroxasulfone (42.5%) • preplant or preemergence • 3 oz/A on coarse soils (Valor @ 2 oz/A + Pyrox @ 1.5 oz/A)
Palmer Amaranth Control with Fierce NTC Fierce 76WG @ 3 oz/A SB-14-10July 22, 201050 DAT
Anthem 2.15L • Cadet (0.0632 lb/gal) + Pyroxasulfone (2.0868 lb/gal) • Residual control of annual grasses and certain broadleaf weeds including pigweed • Use rate: 3.5-7.0 oz/A (?)
Weed Control in Soybeans with Anthem Anthem 2.15SL @ 8 oz/A – PRE Roundup W-Max 5.5SL @ 22 oz/A - POST NTC SB-18-11 June 24 65 DAP
Enlist™ Herbicide Tolerant Soybean • tolerance to 2,4-D + glyphosate + glufosinate (Ignite) • Colex-D™ technology • 2,4-D choline • lower volatility • lower drift potential • enhanced handling/mixing characteristics • reduced odor • 1 Burndown/PRE application + 2 POST applications (R2 stage) • Enlist™ Duo • DMA-Glyphosate (1.71 lb ae/gal) + 2,4-D choline (1.63 lb ae/gal) • 3.5 pt/A • 2015 Product Launch
Enlist Soybeans – 2010 (GA) Ignite 280 2.34SL @ 22 oz/A Weedar 64 4SL @ 17 oz/A N-Pack AMS @ 2.5% v/v Applied May 28 and June 18 NTC SB-09-10 June 28
PPO Herbicide ResistanceThey must be protected!!!! • Resistance has already been reported in other areas!!! • Amaranthus quitensis • 2005 (Bolivia) • Common waterhemp • 2001 (Kansas) • 2002 (Illinois) • 2005 (Missouri) • 2009 (Iowa) • Common ragweed • 2005 (Delaware) • 2006 (Ohio) • Wild poinsettia • 2004 (Brazil)
Final Thoughts • Know your enemy • Start Clean • Tillage and/or Cover Crops • Narrower Row Spacing • Residual herbicides (2) • Reward Programs • Timely POST’s • Irrigation system????? • Roque Escapes
For More Weed Science Info www.gaweed.com