Weed Control in Strip-Tillage Peanuts Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences University of Georgia

The key to weed management in strip-tillage is to start off with a clean seed-bed at planting!

Weeds of Concern

Timing of Burndown 2,4-D in February/March for cutleaf eveningprimrose Smaller weeds Lower rates Avoid drift problem More time to clean out spray tank Burndown @ 3-4 weeks before planting may still need to do something at planting Add Gramoxone to residual herbicides

Burndown Options Primary Tank-mixes based upon weed species glyphosate paraquat Tank-mixes Valor 2,4-D (rotations) Aim - ???? based upon weed species

Glyphosate vs. Paraquat

Effect of glyphosate rate and wheat growth stage on wheat termination – 3 WAT Stage of Growth Glyphosate Rate (lb ai/A) 0.75 1.00 Prior to jointing thru 2 nodes 90 95 3 nodes thru last leaf Early boot thru early heading 75 83 Fully headed to flowering 85 15 trials conducted from 1998-2000 averaged across 11 wheat varieties (From LSU Weed Science Group)

A new formulation of paraquat 2 lbs ai/gallon “User- friendly” alginate alerting agent purgative emetic green dye

Gramoxone Max vs. Gramoxone Inteon G-Max G-Inteon Lbs ai/gal 3.0 2.0 Normal Burndown Rates 1.3-2.0 pts/A 2-3 pts/A

What about Temperature? Depends upon weed and herbicide Warmer is better Watch out for sudden temperature drops

The influence of air temperature on weed control with glyphosate – 14 DAT Source: Hager and Spraque, University of Illinois, 2003.

The influence of air temperature on weed control with paraquat – 14 DAT Source: Hager and Spraque, University of Illinois, 2003.

DNA’s or Yellow Herbicides Prowl/Pendimax vs. Sonalan How do we apply? Rate Method Time EC or H20 weeds up at application irrigation or rainfall

What have we learned about using yellow herbicides in strip-tillage systems??? (2004-2005) Rate 1.5 lb ai/A > 1.00 lb ai/A Formulation Prowl EC = Prowl H20 Timing PRE > 4 WBP > 8 WBP Method Spray > Fertilizer Fertilizer Rate 500 lbs/A > 250 lbs/A

Strongarm or Valor dryland or irrigated weed species rotational crops Crop injury risks Sprayer cleanup ALS resistance

Burndown + PRE Tank-Mixes Usually not a problem earlier applied, less control later in season

Scout Early After Planting Do not wait too late! 7-10 DAP early applications of Gramoxone should control most escapes and set up later POST treatments like Cadre

Grass Problems Later Plan on treating with Poast, Select, or Arrow Texas panicum crowfootgrass Plan on treating with Poast, Select, or Arrow goosegrass

Increased Weed Control Costs 2,4-D @ 1 pt/A ($1.50) + application ($4.00) = $5.50/A Generic Glyphosate @ 1 qt/A ($3.75) + application ($4.00) = $8.75/A Extra 1 pt/A of Prowl = $2.50/A Extra 8 ozs/A of Gramoxone Inteon ($1.68) Arrow @ 8 ozs/A ($8.75) + COC @ 1% v/v ($1.20) + application ($4.00) = $13.95/A Total = $32.38

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