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Peanut Weed Management Update 2008. Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia. Topics For Discussion. Resistance Update Modes of Action Info Aim – Harvest Aid label Palmer Amaranth Herbicide/Fungicide Tank-mix Issues Provost
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Peanut Weed Management Update 2008 Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia
Topics For Discussion • Resistance Update • Modes of Action Info • Aim – Harvest Aid label • Palmer Amaranth • Herbicide/Fungicide Tank-mix Issues • Provost • 2,4-DB issues • Classic Update
GA Confirmed Glyphosate-Resistant Palmer Sites 2005 2006 Current Testing 2007
Herbicide Modes of Action Info • New Table in 2008 Pest Control Handbook • MOA’s listed in crop sections • www.gaweed.com
Harvest Aid Label • September 2007 • 1-2 oz/A • NIS or COC • 7 day PHI • Morningglory • Pigweed • Spiderwort
Managing Palmer Amaranth • Know the enemy • Lots of seed • Grows 1-2”/day • Very competitive • Resistant or not?? • ALS or GR • Residual herbicide • Activation • irrigation or incorporation • Timely POST’s • Avoid overusing PPO’s
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
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) NTC Dual Magnum 7.62EC @ 1 pt/A
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
Provost (10.7 oz/A) + Fulbor + Penatrator Plus + 2,4-DB Richard McDaniel, 2007
Probable Provost Label Changes • No surfactants • No tank-mixes with 2,4-DB • No tank-mixes with EC pyrethroids • Others??
Herbicide/Fungicide Tank-Mixeshttp://www.peanut.ncsu.edu/ag653_web.pdf • Possible combinations are endless • Avoid 3-way mixes if possible • Regional Publication • AGW-653 • NCSU • Updated in May 2007
Contaminated Lots • Contamination if exceeds 250 ppm • Tested Lots • FB-01 = 2,4-D acid (0.294%) • EC-16 = dicamba (0.17%) + 2,4-D acid (0.11%) • EC-16 = Dicamba (0.198%) + 2,4-D acid (0.104%) • EL-31 = 101-117 ppm 2,4-D (3 samples) • CE-04 = 56 ppm of 2,4-D
What will 2,4-D and dicamba do to peanuts???? • Research in GA conducted over the past few years would suggest that 2 oz/A of 2,4-D would not cause many problems. • If contaminated product was applied at 24 oz/A then 2,4-D rate would only be 0.05-0.18 oz/A.
What will 2,4-D and dicamba do to peanuts???? • No data exists for peanut response to dicamba. • Peanuts are more sensitive to dicamba than 2,4-D. • Dicamba rate was equivalent to 0.08-0.1 oz/A (Normal rate for corn is 8 oz/A)
Why is this important? • Peanut response to dicamba • Dicamba resistant crops are in the pipeline • More contamination/drift problems are likely
Classic/Peanut Issues • How much does it really effect TSWV? • How much does it really influence yields?
Classic Research in Georgia • 2000-2007 • 15 locations • 6 varieties • GA Green, GA-02C, GA-03L, AP-3, C-99R, AT-201 • weed-free trials • Results • No interaction between variety and Classic timing • TSWV increased an average of 9% • No effect on peanut yield
The Influence of Classic on the Incidence of TSWV (2000-2007) * * * Classic @ 0.5 oz/A + NIS @ 0.25% v/v Averaged over 6 varieties and 15 locations *Significantly different from NTC (P = 0.05.)
The Influence of Classic on Peanut Yield (2000-2007) Classic @ 0.5 oz/A + NIS @ 0.25% v/v Averaged over 6 varieties and 15 locations P = 0.3321