2007 Peanut Weed Management Update for County Agents Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia Extension Agent Training December 2006 Changes in 2007 Pest Control Handbook Peanut Weed Control Added Firestorm (generic paraquat) where appropriate Included Aim in burndown sections Added generic metolachlors but still included the following warning: The generic formulations of metolachlor (Parallel, Stalwart, Me-Too-Lachlor) have not provided the same length of residual control of certain weeds as similar rates of Dual Magnum formulations in some UGA field trials. Added a specific control rec for tropical spiderwort Table for ALS/GR-resistant pigweed control Added Propel (generic Outlook) Zorial to Solicam Firestorm Chemtura Great Lakes Chemical Corp. + Crompton Corp. 3 lb/gallon of paraquat Similar formulation as Gramoxone Max 5.4 to 10.8 ozs/A = normal rates preplant burndown up to 24 hours after planting Up to 2 ozs/A $5.00/oz Tank-mix with glyphosate IMPOSE Generic liquid Cadre From Makhteshim Agan of North America (MANA) How/Why do we let pigweeds get this big???? Will these herbicides control large pigweeds? Cobra 12.5 ozs/A + 1% v/v applied to 17 tall pigweed 1 DAT 4 DAT 7 DAT 16 DAT 4 ozs/A pt/A + 1% v/v 34 DAT Applied to 17 tall pigweed 2,4-DB/Cobra Test 2006 POST: June 5 (17 tall pigweed) POST2: June 9 Photos taken 24 days after POST application UntreatedCobra 12.5 oz/A 1% v/v POST 2,4-DB 1.1 pt/A + 1% v/v (POST) fb Cobra 12.5 oz/A 1% v/v POST2 Palmer Amaranth Control with Cobra and 2,4-DB 12.5 ozs/A 1.1 pts/A 1% v/v Applied to 17 tall pigweed How do we manage ALS-resistant Palmer amaranth? Need to start using more PRES Valor, Dual Magnum/generics, Outlook Goal????? POST Herbicides Timeliness Cobra, Ultra Blazer, Paraquat Over reliance on PPOs Will need both PREs and POSTs Increased production costs GR-Pigweed/Soybean Test II (2006) 7 WAP Untreated 2 oz/A (PRE) RUWM (POST) What if we do not control Palmer amaranth? Crop (State)DensityYield LossSource Corn (KS) plants/m11-91%Weed Sci : Soybean (AK) plants/m17-68%Weed Sci : Grain sorghum (OK) 1-18 plants/15 m4-63%Weed Tech :23-29 Peanut (NC) 1-5 plants/m28-66%Burke and Wilcut (in-press) Cotton (TX) 1-10 plants/9.1 m13-54%Weed Tech : Does Cobra reduce yields?? Peanut (GA Green) Response to Cobra 78 DAP ozs/A 1% v/v Applied 30 DAP 3556 lbs/A Tifton 4450 lbs/A - Plains 4003 lbs/A Tifton 4319 lbs/A - Plains Classic Use in GA Peanuts 0.5 ozs/A Applied 62 DAE 7 DAT AP-3 GA-02C 11 weed-free field trials in GA 31 data points 77% 8% 23% > 8% Classic Effects on Peanut Yield (P = 0.66)(P = 0.37) 0.5 oz/A % v/v Weed-free Gramoxone Still Works!!!! (for me) Untreated Gramoxone Inteon (12 oz/A) + Storm (1.5 pt/A) + 80/20 (0.25% v/v) PE DAT Speed, Nozzle Tip, GPA Effects 7 MPH Tractor Speed LSD 0.10 = 3 Gramoxone Inteon (GI) and Basagran (B) Effects on Peanut Yield GA-02C Averaged over 4 timings (7, 14, 22, 28 DAC) Included 0.25% v/v Weed-free P = 0.63 Cadre or Gramoxone fb Cadre??? 4 field trials conducted in lb/A average yield increase when Gramoxone + Basagran was used prior to Cadre compared to Cadre alone It only takes a 64 lbs/A increase of peanuts to pay for this treatment Peanut (GA-02C) Response to Roundup Weathermax 112 DAP Roundup 12 ozs/A Applied 71 DAP 8 DAT Peanut Yield Loss Caused by Roundup WeatherMax GA-O2C Ponder Farm