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AUTHOR
Stanley Culpepper
Extension Weed Specialist
University of Georgia
Tifton, GA

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TABLE OF CONTENTS
  1. Living with Palmer amaranth in Georgia cotton
  2. Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth.
  3. What makes Palmer a super weed?
  4. Number of Seed Produced per Plant - Glyphosate-Resistant Weeds in US
  5. Weakness of a super weed?
  6. Progress during 2009?
  7. Palmer requires a significant amount of sunlight to emerge!!
  8. Palmer requires a significant amount of sunlight to emerge!!
  9. Palmer requires a significant amount of sunlight to emerge!!
  10. Palmer requires a significant amount of sunlight to emerge!!
  11. Palmer amaranth response to cover crops
  12. Significant Residue
  13. Management Program?
  14. Tillage
  15. Number of Palmer Amaranth Plants During Early Season
  16. Palmer amaranth seedling density
  17. Influence of burial depth on Palmer amaranth emergence
  18. Most Palmer amaranth emerges from top inch
  19. Palmer amaranth seed longevity
  20. Palmer amaranth response to deep tillage
  21. Management Program?
  22. Most Palmer amaranth emerges from top inch
  23. Palmer amaranth response to deep tillage and cover crops
  24. Reduction in Palmer emergence as affected by deep turning/cover crop residue at 16 DAP
  25. GR Palmer amaranth control at harvest with Roundup-based systems
  26. Seed cotton yield (lb/A) with Roundup-based systems
  27. Developing Integrated Programs
  28. Potential Benefits
  29. Management Program?
  30. Dryland Conservation Tillage
  31. Apply 29 oz of Ignite Prior to 3 inch Palmer
  32. No recommendation on handout for RR dryland in conservation tillage?
  33. Other Information
  34. Controlling 5 inch Glyphosate-Resistant Palmer amaranth at Burndown.
  35. Palmer control at planting, burndown applied 17 d earlier.
  36. Change in Valor Label?
  37. How Effective Are Preplant Applications?
  38. Change in Valor Label?
  39. Treflan
  40. Reflex
  41. Percent GR Palmer amaranth control 28 DAP.
  42. Palmer control from acetochlor, S-metolachlor, and metolachlor.
  43. Palmer control
  44. Tobacco:Spartan + Yellow 2008
  45. Palmer amaranth seedbank - it is the key!
  46. Integrating cover crop residue and moldboard plowing into glyphosate-resistant Palmer amaranth management programs will be key!



SLIDE CONTENTS
  1. Taproot of Palmer Amaranth Allen 2009 Living with Palmer amaranth in Georgia cotton
  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. What makes Palmer a super weed? Herbicide resistance? Growth rate? Large stature? Competitive ability? Reducing harvest efficacy? Seed production? Rapid spread?
  4. 230 K 250 28 K 309 K Giant ragweed 450 K Number of Seed Produced per Plant Glyphosate-Resistant Weeds in US Ragweed = Harrison et al. 2001; johnsongrass = Warwick and Black (1983); horseweed = Regehr and Bazzaz (1979); waterhemp = Nordby and Hartzler (2004); Palmer amaranth = Macrae et al (2009). Johnson-grass Horseweed Waterhemp Palmer amaranth
  5. Weakness of a super weed? Emergence depth! Seed life longevity? Light requirement for emergence. Economic survival will depend on managing the seedbank!!!!
  6. Progress during 2009? Cover crops Tillage Tillage + plus cover crops Herbicides
  7. Palmer requires a significant amount of sunlight to emerge!!
  8. Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby No deep tillage No cover crop No deep tillage Rye cover crop Palmer amaranth response to cover crops. Macon County, GA. 2009.
  9. Significant Residue 2009 rye emerging through 2008 rye residue
  10. Management Program? Cover crops Tillage Deep tillage and cover crops?
  11. No Deep Tillage Deep Turn No Herbicide Treatment Number of Palmer Amaranth Plants During Early Season. Macon Co., Georgia 2008.*
  12. Palmer amaranth seedling density
  13. Influence of burial depth on Palmer amaranth emergence Keeley et al. (1987) reported 36-44% emergence at 0-1, 7% at 2, and 2% at 3.
  14. Most Palmer amaranth emerges from top inch
  15. Palmer amaranth seed longevity *Data are combined over 4 burial depths: 0.5, 1, 4, 16
  16. Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby No deep tillage No cover crop Deep tillage No cover crop Palmer amaranth response to deep tillage. Macon County, GA. 2009.
  17. Management Program? Cover crops Tillage Deep tillage and cover crops?
  18. Most Palmer amaranth emerges from top inch
  19. Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby No deep tillage No cover crop Deep tillage Rye cover crop Palmer amaranth response to deep tillage and cover crops. Macon County, GA. 2009.
  20. 65 b Drill Middle percent 47 c 46 c Reduction in Palmer emergence as affected by deep turning/cover crop residue at 16 DAP. Macon Co., GA 2009. Rye cover Deep turn + Rye cover 96 a 94 a 50 c Deep turn Drill Middle Drill Middle Non-treated: 620 plant/m2. No herbicides applied.
  21. 81 b No deep turn No Cover Deep turn No cover Rye 7 foot when killed, rolled, planted. Deep turn 12 inch in previous fall. Herbicide program: Direx + Reflex + Staple PRE; RU + Parrlay POST, Direx + MSMA at layby. percent 63 c 80 b 98 a GR Palmer amaranth control at harvest with Roundup-based systems. Macon Co., GA 2009. No deep turn Rye Cover Deep turn Rye Cover
  22. 1627 b No deep turn No Cover Deep turn No cover Rye 7 foot when killed, rolled, planted. Deep turn 12 inch in previous fall. Herbicide program: Direx + Reflex + Staple PRE; RU + Parrlay POST, Direx + MSMA at layby. 1298 d 1524 bc 2078 a Seed cotton yield (lb/A) with Roundup-based systems. Macon Co., GA 2009. No deep turn Rye Cover Deep turn Rye Cover
  23. Developing Integrated Programs Makes growers nervous Easy to adopt
  24. Potential Benefits Labor, erosion, etc.. Prevents GR horseweed Prevents GR ryegrass Reduces Palmer 80%+ Moisture conservation herbicides overtime Higher yields??????
  25. Management Program? Tillage Cover crops Deep tillage and cover crops? Herbicide programs
  26. Dryland Conservation Tillage Prowl + Reflex PRE Roundup + Dual POST Diuron + MSMA PD Prowl + Reflex PRE Ignite + Dual POST Diuron + MSMA PD
  27. Ignite 23 oz/A APPLY 29 OZ OF IGNITE PRIOR TO 3 INCH PALMER WATER VOLUME AND NOZZLE TYPE IS CRITICAL
  28. No recommendation on handout for RR dryland in conservation tillage? Run aggressive RR program Plant rye to produce tremendous cover Hand weed!!!
  29. Other Information Burndown Acetochlor PPI herbicide applications Palmer seedbank
  30. Controlling 5 inch Glyphosate-Resistant Palmer amaranth at Burndown. Macon Co., GA 2008.* 0 c 87 b 94 a 58 b Roundup Parazone 1.33 pt 70 b Parazone + 2,4-D (1.5 pt) Parazone + Clarity (8 oz) Parazone + Diuron (1.8 pt)
  31. Palmer control at planting, burndown applied 17 d earlier. Macon Co., GA 2009. 90 b Valor preplant Direx preplant 99 a
  32. Change in Valor Label? 1. Apply Valor and then run strip tillage: 7 day plant back
  33. HOW EFFECTIVE ARE PREPLANT APPLICATIONS?
  34. Change in Valor Label? When you have greater than 30% crop residue: 2. Run strip tillage and then spray Valor: Label says 21 day plant back
  35. TREFLAN PPI PRE
  36. REFLEX PPI PRE
  37. Percent GR Palmer amaranth control 28 DAP. Macon Co., GA. 2009. 81 a Prowl 51 b 46 b 86 a Treflan PRE APPLICATIONS RAIN 12 d after planting PRE PPI PRE PPI
  38. Palmer control from acetochlor, S-metolachlor, and metolachlor. Macon Co., GA 2009. 50 c acetochlor (1.13 lb) 80 a S-metolachlor (Dual Mag, 0.95 lb) metolachlor (Parrlay, 1.3 lb) 77 a No Palmer up at time of application. Layby of RU + Direx applied 19 d after POST.
  39. Tobacco:Spartan + Yellow 2008 Soybean- Roundup 2008 A.C.York, 2009
  40. Palmer amaranth seedbank it is the key! YEAR 1: 5 Palmer females escape Produce 2,000,000 seeds in cotton (50% germ) YEAR 2: Weed program = 99.9% control 1,000 plants per acre left at harvest 400 female plants/A 160,000,000 seeds produced in cotton (50%) YEAR 3: Weed program 99.9% control 80,000 plants per acre left at harvest 32,000 female plants/A = 1.28 X 1010 seed/A
  41. Integrating cover crop residue and moldboard plowing into glyphosate-resistant Palmer amaranth management programs will be key! QUESTIONS OR COMMENTS?