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J.E. Chafin, A.S. Culpepper, and L.B. Braxton
University of Georgia

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TABLE OF CONTENTS
  1. Palmer amaranth, benghal dayflower, and broadleaf signalgrass response to glufosinate applied alone or mixed with 2,4-D, or dicamba
  2. Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth.
  3. Biotypes with multiple resistance to glyphosate and ALS herbicides are becoming more common across Georgia.
  4. Cultivation
  5. Impact of GR Palmer amaranth in Georgia counties with severe infestations.
  6. Dryland Conservation Tillage
  7. Glufosinate 0.42 lb on 5 in. Palmer amaranth
  8. Future Technology: 2,4-D or Dicamba Resistant Cotton
  9. Objective
  10. Hypothesis
  11. Trial Locations
  12. Treatments
  13. Application Methods
  14. Conditions at Time of Application
  15. Data Reported & Statistical Analysis
  16. Percent GR Palmer amaranth control at 20 d.
  17. Non-treated vs glufosinate
  18. 2,4-D at 0.75 lb
  19. dicamba 0.5 lb
  20. Percent GR Palmer amaranth control at 20 d
  21. glufosinate vs glufosinate + 2,4-D 0.75 lb
  22. glufosinate vs glufosinate + dicamba 0.5 lb
  23. Percent carpetweed control at 20 d
  24. 2,4-D 0.5 lb at 10 DAT
  25. Percent carpetweed control at 20 d
  26. Benghal dayflower infesting Roundup Ready cotton
  27. Percent benghal dayflower control at 20 d
  28. Percent benghal dayflower control at 20 d when mixed with Ignite
  29. Percent broadleaf signalgrass control at 20 d
  30. Percent broadleaf signalgrass control at 20 d when mixed with Ignite
  31. Pitted morningglory controlled 97 to 99% by all treatments
  32. Conclusions-Palmer amaranth
  33. Conclusions-Carpetweed
  34. Conclusions-Benghal dayflower
  35. Conclusion-Broadleaf signalgrass
  36. Future Research



SLIDE CONTENTS
  1. Palmer amaranth, benghal dayflower, and broadleaf signalgrass response to glufosinate applied alone or mixed with 2,4-D, or dicamba J.E. Chafin, A.S. Culpepper, and L.B. Braxton University of Georgia Department of Crop and Soil Sciences January 2010
  2. Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth. 2004 – 1 county 2005 – 2 counties 2006 – 7 counties 2007 – 10 counties 2008 – 18 counties
  3. Biotypes with multiple resistance to glyphosate and ALS herbicides are becoming more common across Georgia.
  4. 88 26 % acres 25 20 0 0 45 *Average of Macon, Taylor, Sumpter, Schley, and Dooly counties Glufos. (Ignite) systems Cultivation Hand weeding 0 Impact of GR Palmer amaranth in Georgia counties with severe infestations.* Acres (%) treated with at least two residual herbicide
  5. Dryland Conservation Tillage Prowl + Reflex PRE Roundup + Dual POST Direx + MSMA PD Prowl + Reflex PRE Ignite + Dual POST Direx + MSMA PD
  6. Glufosinate 0.42 lb on 5 in. Palmer amaranth “The challenge is making applications of glufosinate to target plants less than 10 cm in height” (Coetzer et al. 2002).
  7. Future Technology: 2,4-D or Dicamba Resistant Cotton 2,4-D resistant cotton 2,4-D sensitive cotton
  8. Objective Determine the response of glyphosate- resistant Palmer amaranth to glufosinate, 2,4-D (Weedar), or dicamba (Clarity) applied alone and glufosinate mixed with 2,4-D or dicamba. Carpetweed, benghal dayflower, broadleaf signalgrass, and pitted morningglory
  9. Hypothesis Tank mixtures of glufosinate + 2,4-D or dicamba will be more effective in controlling broadleaf weeds than glufosinate alone.
  10. Trial Locations Macon County (Glyphosate-resistant Palmer amaranth) Chula (Palmer amaranth, carpetweed) Sunbelt Expo (benghal dayflower, broadleaf signalgrass, pitted morningglory)
  11. Treatments A factorial arrangement of two “glufosinate” options and seven “tank mix” options Ignite Option: None or Ignite at 0.42 lbs Tank mix option: 2,4-D, dicamba, or none 2,4-D (Weedar 64) .5, 0.75, 1.0 lb/ac Dicamba (Clarity) .25, 0.5, 1.0 lb/ac None
  12. Application Methods Backpack sprayer Broadcast Overtop 15 gal/Ac Drift Guard T-Jet 11002 VS Early morning application 7-9 inch weed
  13. Conditions at Time of Application Moist/Wet Sunny conditions Air Temperature: 76-95 F % Relative Humidity: 56-74
  14. Data Reported & Statistical Analysis Palmer amaranth control was combined over the three locations. Carpetweed, benghal dayflower, broadleaf signalgrass, and pitted morningglory Weed control at 20 d is reported; interaction means are reported.
  15. Percent GR Palmer amaranth control at 20 d. Average 3 loc., GA, 2009. 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 69 cd 77 bc 73 bcd 79 b 65 d 77 bc 90 a Glufos-inate Herbicide applied alone
  16. Non-treated glufosinate 12 DAT
  17. 2,4-D at 0.75 lb 12 DAT 24 DAT
  18. dicamba 0.5 lb 12 DAT 24 DAT
  19. 69 cd 77 bc Glufos-inate 0.5 lb 73 bcd 79 b 65 d 77 bc 90 a 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 91 a 92 a 96 a 91 a 91 a 96 a = control when mixed with Ignite Percent GR Palmer amaranth control at 20 d. Average 3 loc., GA, 2009.
  20. glufosinate glufosinate + 2,4-D 0.75 lb 12 DAT
  21. glufosinate glufosinate + dicamba 0.5 lb 12 DAT
  22. 66 b 58 b Glufos-inate 0.5 lb 99 a 63 b 55 b 57 b 60 b 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba Percent carpetweed control at 20 d. Chula, GA, 2009.
  23. 2,4-D 0.5 lb at 10 DAT
  24. Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 99 a 99 a 99 a 99 a 99 a 99 a = control when mixed with Ignite Percent carpetweed control at 20 d. Chula, GA, 2009. 66 b 58 b 63 b 55 b 57 b 60 b 99 a
  25. Benghal dayflower infesting Roundup Ready cotton
  26. Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba Percent benghal dayflower control at 20 d. Sunbelt Expo, GA, 2009. 91 a 98 a 98 a 68 c 84 b 93 a 68 c
  27. Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 97 a 94 a = control when mixed with Ignite Percent benghal dayflower control at 20 d. Sunbelt Expo, GA, 2009. 91 a 98 a 98 a 68 c 84 b 93 a 68 c
  28. Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba Percent broadleaf signalgrass control at 20 d. Sunbelt Expo, GA, 2009. 96 a 0 b 0 b 0 b 0 b 0 b 0 b
  29. Glufos-inate 0.5 lb 0.75 lb 1.0 lb 1.0 lb 0.25 lb 0.5 lb 2,4-D dicamba 93 ab 92 ab = control when mixed with Ignite Percent broadleaf signalgrass control at 20 d. Sunbelt Expo, GA, 2009. 91 ab 91 ab 88 b 92 ab 96 a
  30. Pitted morningglory controlled 97 to 99% by all treatments Everman et al. noted greater than 90% control with glufosinate applied POST on pitted morningglory.
  31. Conclusions-Palmer amaranth Glufosinate alone only provided 73% control 2,4-D alone provided 69-79% control Dicamba alone provided 69-90% Tank mixtures of glufosinate+2,4-D or dicamba at least 91% control
  32. Glufosinate alone provided 99% control 2,4-D alone provided 58-66% Dicamba alone provided 55-60% All rates of glufosinate+2,4-D or dicamba provided 99% control Conclusions-Carpetweed
  33. Conclusions- Benghal dayflower Glufosinate alone provided 63% control 2,4-D provided 91-98% control; combinations with glufosinate could not improve control Dicamba control ranges from 68-93% but when combined with glufosinate control ranges from 93-97%
  34. Conclusion-Broadleaf signalgrass Glufosinate alone provided 96% control and no control with 2,4-D or dicamba alone 2,4-D mixed with glufosinate, control ranged from 88-91%; at 1 lb/ac of 2,4-D the control was 8% less than glufosinate alone Dicamba mixed with glufosinate provided 92-93% control
  35. Future Research 2,4-D resistant cotton 2,4-D sensitive cotton