Comparison of Conventional, Roundup Ready, and Liberty-Link Cotton Weed Management Programs in Two Tillage Systems

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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
Monks Auburn University Wilson Faircloth
USDA-ARS, Dawson Ga.
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Alabama 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.

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Research 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.

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Materials and MethodsLocations
Tennessee Valley Research and Extension Center
Belle Mina (Decatur clay loam)
Wiregrass Research and Extension
Center Headland (Dothan sandy loam)
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Materials and MethodsExperimental Particulars

• Time frame 2005, 2006
• Varieties FM 966, FM 960 RR, FM 966 LL
• Conventional and reduced tillage.
• Six Treatments
• Replicated four times
• Plot Dimensions both north and south AL four
  rows by 40 long, each plot separated by four
  border rows

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Materials and MethodsExperimental 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

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Tillage/Herbicide Treatments
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Costs of Tillage/Weed Systems( per acre)
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Effect of Herbicide System Fiber Strength 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
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Effect of Tillage on Broadleaf Weed Control
(north Alabama)
Tillage System Control 2005 Control 2006
Reduced till 98 93
Conv till 98 84
LSD (.05) NS 5
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Effect of Tillage on Cotton Yield and Economic
Return (south Alabama)
Tillage System Lint Lb/A /System
Reduced till 1576 700
Conv till 1425 625
LSD (.05) 105 ----
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Effect of Herbicide System on Weed Control 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 ----
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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.

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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.

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Implications 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.

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Support

• 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.

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Questions?
Q