comparison of conventional, roundup ready, and liberty-link cotton weed management programs in two...
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Comparison of Conventional, Roundup Ready, and Liberty-Link Cotton Weed Management Programs
in Two Tillage Systems
Michael Patterson, Bob Goodman and Dale MonksAuburn University
Wilson Faircloth USDA-ARS, Dawson Ga.
Alabama CottonAlabama Cotton
In Alabama and most of the southeast, Roundup Ready Cotton comprises 90% to 95% of the acreage.
The remainder of cotton acreage is planted in conventional (non-transgenic) or Liberty-Link varieties.
Over 75% of Alabama cotton is grown in some form of reduced tillage.
Research ObjectivesResearch Objectives
1. Evaluate cotton production in tilled and reduced till systems using Roundup Ready, Liberty Link, and conventional weed management programs.
2. Evaluate the economic viability of each tillage/weed management system.
3. Philosophize on the implications of the data.
Materials and MethodsMaterials and MethodsLocationsLocations
Tennessee Valley Research and Extension Center
Belle Mina(Decatur clay loam)
Wiregrass Research and Extension Center
Headland(Dothan sandy loam)
Materials and MethodsMaterials and MethodsExperimentalExperimental Particulars Particulars
Time frame: 2005, 2006Varieties: FM 966, FM 960 RR, FM 966 LLConventional and reduced tillage.Six Treatments Replicated four timesPlot Dimensions: both north and south AL =
four rows by 40’ long, each plot separated by four border rows
Materials and MethodsMaterials and MethodsExperimentalExperimental Particulars Particulars
Tractor mounted sprayer used: 15 GPA.
Conventional tillage: north AL = disk 2X, roterra. south AL = subsoil, disk, roterra.
Reduced tillage: north AL = notill into wheat, south AL = strip till into wheat.
Soil types: north AL = clay loam. south AL = sandy loam
Tillage/Herbicide Treatments Tillage/Herbicide Treatments
Trt.No. Tillage/Variety Soil-applied herbs POT herb-timing PDS herbs
1 Reduced/ RR Prowl-pre Rdup 3, Envoke 8 Layby Pro
2 Convent/RR Prowl-ppi Rdup 3, Envoke 8 Layby Pro
3 Reduced/LL Prowl-pre Ignite 3, Envoke 8 Layby Pro
4 Convent/LL Prowl-ppi Ignite 3, Envoke 8 Layby Pro
5 Reduced/CV Prowl+Cotoran-pre Staple 2, Envoke 8 Layby Pro
6 Convent/CV Prowl-ppi, Cot-pre Staple 2, Envoke 8 Layby Pro
Application and Timing to Cotton
Costs of Tillage/Weed Systems($ per acre)Costs of Tillage/Weed Systems($ per acre)
Trt.No. Tillage/Variety Tech fee Tillage/Herb* Total*
1 Reduced/ RR 33 53/63 86/962 Convent/RR 33 55/63 88/963 Reduced/LL 15 57/67 72/824 Convent/LL 15 59/67 74/825 Reduced/CV 0 75/85 75/856 Convent/CV 0 77/85 77/85
*north AL / south AL
Effect of Herbicide System Fiber Strength Effect of Herbicide System Fiber Strength and Percent Lint (north Alabama)and Percent Lint (north Alabama)
Herbicide
System
Strength of Fiber g/tex
Percent Lint
2006
RR variety 29.7 44.4
LL variety 31.7 43.1
CV variety 31.7 44.6
LSD (.05) 0.7 0.8
Effect of Tillage on Broadleaf Weed Effect of Tillage on Broadleaf Weed Control (north Alabama) Control (north Alabama)
Tillage
System
%Control
2005
%Control
2006
Reduced till 98 93
Conv till 98 84
LSD (.05) NS 5
Effect of Tillage on Cotton Yield and Effect of Tillage on Cotton Yield and Economic Return (south Alabama)Economic Return (south Alabama)
Tillage
System
Lint
Lb/A $/System
Reduced till 1576 700
Conv till 1425 625
LSD (.05) 105 ----
Effect of Herbicide System on Weed Control Effect of Herbicide System on Weed Control and Cotton Yield (south Alabama)and Cotton Yield (south Alabama)
Variable RR LL CV LSD .05
% Grass 95 94 89 3
% Brdlf 94 89 85 6
Lint #/A 1564 1461 1326 125
% Lint 41.6 39.4 40.8 0.9
$/System 686 649 578 ----
SUMMARY (north Alabama)SUMMARY (north Alabama)
No yield differences due to herbicide/tillage system in.
Decrease in late season broadleaf weed control for Conventional till in 2006.
Slight and inconsequential differences in strength and turnout between varieties.
Summary (south Alabama)Summary (south Alabama)
Greater yield in strip till than in conventional till in both years.
Greater yield in RR and LL systems than in conventional herbicide systems in both years.
Strip till returned $75.00 per acre more than conventional on average.
RR and LL returned $108.00 and $71.00 more per acre respectively than conventional herbicide system.
Implications of dataImplications of data
Probable reduction in economic return if south AL cotton growers return to conventional tillage and conventional herbicide technology.
New post-emergent herbicide technology with activity on pigweed is needed in light of the recent discovery of glyphosate and ALS resistant pigweed biotypes.
SupportSupport
Researchers gratefully acknowledge the financial assistance of Cotton Incorporated and Alabama cotton growers in conduction of this research.
Reseachers also gratefully acknowledge the support of Alabama Agricultural Experiment Station personnel at the Tennessee Valley and Wiregrass Research and Extension Centers.