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Managing Palmer Amaranth Peanuts Field Corn Soybeans. Eric P. Prostko Extension Weed Specialist Dept. of Crop & Soil Sciences The University of Georgia. Managing Palmer Amaranth. Know your enemy Resistant or not?? ALS or GR Residual herbicide Activation (irrigation or incorporation)
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Managing Palmer AmaranthPeanutsField Corn Soybeans Eric P. Prostko Extension Weed Specialist Dept. of Crop & Soil Sciences The University of Georgia
Managing Palmer Amaranth • Know your enemy • Resistant or not?? • ALS or GR • Residual herbicide • Activation (irrigation or incorporation) • Timely POST’s • Avoid overusing PPO’s
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
Palmer Amaranth is very competitive!!! • Yield loss caused by 1 plant/meter of row • Soybean (27%) • Peanut (28%) • Corn (32%) • Cotton (48%)
GA Confirmed Glyphosate-Resistant Palmer Sites 2005 2006 Current Testing 2007
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
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
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
UFO’s Bigfoot Applications to 2” tall pigweed Things You Do Not Often See in Georgia
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
Herbicide Modes of Action Info • New Table in 2008 Pest Control Handbook • MOA’s listed in crop sections • www.gaweed.com
Palmer Amaranth Control in PeanutsMacon County, GA – 2007 (38 DAT) NTC Valor SX 51WG @ 3 oz/A
Palmer Amaranth Control in PeanutsMacon County, GA – 2007 (38 DAT) Dual Magnum 7.62EC @ 1 pt/A NTC
Palmer Amaranth Control in Peanut with PRE Herbicides Valor @ 3 oz/A Dual Magnum @ 1 pt/A Stalwart @ 1 pt/A Outlook @ 1 pt/A
2,4-DB fb Cobra or Ultra Blazer????? 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
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
GR-Palmer Amaranth Control in Field Corn May 31, 2007 (38 DAP) NTC Halex GT 4.38SC @ 4 pt/A 80/20 @ 0.25% v/v AMS @ 8.5 lbs/100 gals EPOST (18 DAP) CN-07-07
Palmer Amaranth Control in Sorghum-Sudangrass Silage NTC 2,4-D amine @ 1 pt/A (27 DAT) GS-01-07
GR-Palmer Amaranth Control in Soybean – 2007 (83 DAT) Untreated Boundary 6.5EC @ 1.8 pt/A SB-01-07
GR-Palmer Amaranth Control in Soybean – 2007 (83 DAT) Untreated Prefix 5.2EC @ 2.03 pt/A SB-01-07
GR-Palmer Amaranth Control in Soybean – 2007 (77 DAT) Untreated Valor SX 51WG @ 3 oz/A SB-02-07
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
Managing Palmer Amaranth • Know your enemy • Resistant or not?? • ALS or GR • Residual herbicide • Timely POST’s • Avoid overusing PPO’s