Weed Control in Grain Sorghum

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The Effect of Spray Tips and Spray Volumes on
Glyphosate and Paraquat Efficacy
Cathy L. Minihan, Dallas E. Peterson, Robert E.
Wolf, J. Anita Dille
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INTRODUCTION

• Higher spray volumes and smaller spray droplets
• theoretically should provide the most thorough
• coverage assuming the spray droplets reach the
• intended target.
• Spray volume, pressure, and spray tips influence
  
• spray droplet size.
• Thorough spray coverage is probably more
  critical
• with contact than systemic herbicides.

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OBJECTIVE

• Determine the effect of spray tips and spray
• volumes on paraquat and glyphosate efficacy
  with
• early and late postemergence applications to
  oats.

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MATERIALS AND METHODS

• Location Years Manhattan, KS
• 2000, 2001
• Experimental Design 2 x 3 x 3 Factorial
• Herbicides
• Spray Tips
• Spray Volumes
• Herbicides Glyphosate Paraquat
• Spray Tips XR Flat Fan
• Turbo TeeJet
• Air Induction

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MATERIALS AND METHODS

• Spray Volumes 47 L ha-1 (110015)
• 94 L ha-1 (11003)
• 187 L ha-1 (11006)
• Spray Pressures 262-276 kPa
• Early Postemergence Oats 15 cm
• Late Postemergence Oats 50 cm
• Visual Ratings 1, 2, 4 WAT

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Air Induction
XR Flat Fan
Turbo TeeJet
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RESULTS AND DISCUSSION EARLY POSTEMERGENCE EXPER
IMENTS 2000-2001
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Early Postemergence Oat Control 2 WAT As
Influenced By Herbicide and Spray Tips, 2000.
(averaged across spray volumes)
a
a
b
c
c
d
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Early Postemergence Oat Control 2 WAT As
Influenced By Spray Volume, 2000. (averaged
across herbicides and tips)
LSD(0.05)NS
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Early Postemergence Oat Control 2 WAT As
Influenced By Herbicides and Spray Volumes, 2001.
(averaged across spray tips)
a
b
c
c
d
d
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Early Postemergence Oat Control 2 WAT As
Influenced By Spray Tips And Volumes, 2001.
(averaged across herbicides)
a
b
bc
cd
e
de
f
fg
g
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EARLY POSTEMERGENCE

• 2000
• HERBICIDE X SPRAY TIP SIGNIFICANT
• SPRAY VOLUMES NOT SIGNIFICANT
• 2001
• HERBICIDE X VOLUME SIGNIFICANT
• SPRAY TIP X VOLUME SIGNIFICANT

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LATE POSTEMERGENCEEXPERIMENTS2000-2001
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Late Postemergence Oat Control 2 WAT As
Influenced By Spray Tips, 2000. (averaged across
herbicides volumes)
LSD(0.05)NS
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Late Postemergence Oat Control 2 WAT As
Influenced By Spray Volumes, 2000. (averaged
across herbicides spray tips)
a
a
b
16
Late Postemergence Oat Control 2 WAT As
Influenced By Spray Tips, 2001. (averaged across
herbicides volumes)
LSD(0.05)NS
17
Late Postemergence Oat Control 2 WAT As
Influenced By Herbicide and Spray Volumes, 2001.
(averaged across spray tips)
a
b
c
c
d
e
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LATE POSTEMERGENCE

• 2000
• SPRAY VOLUME SIGNIFICANT
• SPRAY TIPS NOT SIGNIFICANT
• 2001
• HERBICIDE X VOLUME SIGNIFICANT
• SPRAY TIPS NOT SIGNIFICANT

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47 L ha-1
94 L ha-1
187 L ha-1
Late postemergence paraquat 1 WAT applied with
spray volumes of 47, 94, 187 L ha-1, 2000.
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47 L ha-1
94 L ha-1
187 L ha-1
Late postemergence glyphosate 1 WAT applied with
spray volumes of 47, 94, 187 L ha-1, 2000.
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94 L ha-1
187 L ha-1
47 L ha-1
Late postemergence oat control 2 WAT with
glyphosate at 47, 94, and 187 L ha-1 spray
volumes , 2000.
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CONCLUSIONS

• Even though oat control with glyphosate and
• paraquat was different, the response to spray
• tips and spray volumes was similar.
• Oat control at 47 and 94 L ha-1 was equal or
• better than at 187 L ha-1 with both
  herbicides.
• Oat control with the Turbo Teejet, Air Induction,
  and XR Flat Fan tips was similar.

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IMPLICATIONS

• Lower spray volumes can provide equal or better
  weed control with more efficient use of time and
  resources.
• Use of new spray tips that produce larger spray
  droplets reduce the risk of spray drift while
  maintaining herbicide efficacy.

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FUTURE RESEARCH

• Confirm results with different herbicides and
  weeds.
• Evaluate new spray tips and delivery systems as
  they are introduced into the market.

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ACKNOWLEDGEMENTS

• Kansas State University
• Research and Extension
• Syngenta
• Successful Farming

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K STATE
Research and Extension