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RR Cotton Tolerance to Glyphosate and Managing Difficult to Control Weeds

RR Cotton Tolerance to Glyphosate and Managing Difficult to Control Weeds. A. Stanley Culpepper. Glyphosate Overtop Prior to 5th Leaf. 1. 2 applications 2. applications 10 days apart 3. 2 nodes of growth. Glyphosate Overtop After 4th Leaf?.

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RR Cotton Tolerance to Glyphosate and Managing Difficult to Control Weeds

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  1. RR Cotton Tolerance to Glyphosate and Managing Difficult to Control Weeds A. Stanley Culpepper

  2. Glyphosate Overtop Prior to 5th Leaf 1. 2 applications 2. applications 10 days apart 3. 2 nodes of growth

  3. Glyphosate Overtop After 4th Leaf?

  4. Lint Cotton Yields in RR Cotton when Treated Topically with Glyphosate at Various Growth Stages a a a b b 1) Ten plants per plot were hand harvested on October 10, 1999 in Moultrie, GA. 2) Roundup Ultra applied at 1 qt/A broadcast over-the-top. Conventional plots treated with standard herbicide system.

  5. Lint Yields (Nodes 5-14) in RR Cotton when Treated Topically with Glyphosate at Various Growth Stages a a a b b 1) Ten plants per plot were hand harvested on October 10, 1999 in Moultrie, GA. 2) Roundup Ultra applied at 1 qt/A broadcast over-the-top. Conventional plots treated with standard herbicide system.

  6. Unopened Bolls in RR Cotton when Treated with Glyphosate Topically at Various Growth Stages 1) Ten plants per plot were hand harvested on October 10, 1999 in Moultrie, GA. 2) Roundup Ultra applied at 1 qt/A broadcast over-the-top. Conventional plots treated with standard herbicide system.

  7. Glyphosate 9-leaf No Glyphosate

  8. Glyphosate Overtop After 4th Leaf Stage • Can cause boll shed, delay maturity Salvage treatment only

  9. Is Stem Absorption of Glyphosate Directed in RR Cotton a Concern? No noted concerns in field trials Lab data from North Carolina, Georgia, and Mississippi?

  10. Directing Glyphosate in RR Cotton? • Precision PD or hooded sprayers

  11. Directing Glyphosate in RR Cotton? • Precision PD or hooded sprayers • Direct spray to the base of the cotton plants

  12. Directing Glyphosate in RR Cotton? • Precision PD or hooded sprayers • Direct spray to the base of the cotton plants • Contact of spray with cotton leaves should be avoided to the maximum extent possible

  13. Directing Glyphosate in RR Cotton? • Precision PD or hooded sprayers • Direct spray to the base of the cotton plants • Contact of spray with cotton leaves should be avoided to the maximum extent possible • Place nozzles in low position directing a horizontal spray pattern under the cotton leaves to contact weeds in the row

  14. Cotton Yield After Various Glyphosate Applications. Moultrie, 2000.* a a a b b Lint yield (Lb/A) Topical 1- & 4-lf Standard system Topical 1-, 4-, & 12-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 55

  15. Number of Bolls on Nodes 5-10 After Various Glyphosate Applications. Moultrie, 2000.* a a a # of bolls/ 6 feet b Topical 1- & 4-lf Standardsystem Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 52

  16. Boll Weights from Nodes 5-10 After Various Glyphosate Applications. Moultrie, 2000.* a a a Grams/6 feet b Topical 1- & 4-lf Standardsystem Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 52

  17. Number of Bolls on Nodes >10 After Various Glyphosate Applications. Moultrie, 2000.* a a a a # of bolls/6 feet Topical 1- & 4-lf Standardsystem Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = NS

  18. Boll Weights from Nodes >10 After Various Glyphosate Applications. Moultrie, 2000.* a a a a Grams/6 feet Topical 1- & 4-lf Standardsystem Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = NS

  19. Number of Vegetative Bolls After Various Glyphosate Applications. Moultrie, 2000.* b # of bolls/6 feet a a a Topical 1- & 4-lf Standardsystem Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 4

  20. Vegetative Boll Weights After Various Glyphosate Applications. Moultrie, 2000.* b Grams/6 feet a a a Topical 1- & 4-lf Standardsystem Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 18

  21. Precision and Sloppy Applied Glyphosate

  22. Precision and Sloppy Applied Glyphosate

  23. Directing After 4-leaf Stage? • Glyphosate preferred for grasses or perennials • Otherwise, conventional chemistry preferred

  24. Directing After 4-leaf Stage? • Glyphosate preferred for grasses or perennials • Otherwise, conventional chemistry preferred 1. Better morningglory control 2. Residual weed control 3. Resistant management strategy 4. Avoid weed shifts 5. Reduce risk of boll shed

  25. Weeds Difficult to Control by Glyphosate?

  26. Cutleaf Eveningprimrose Response to Burndown Herbicides Treatment Rating Gramoxone F Gramoxone + Direx G Glyphosate F Glyphosate + Direx G Glyphosate + Harmony Extra F-G Glyphosate + Clarity G Glyphosate + 2,4-D E

  27. Cutleaf Eveningprimrose Control by Glyphosate. Tifton, 2000.* % control *Roundup Ultra applied at 1 qt/A.

  28. Cutleaf Eveningprimrose Control by 2,4-D. Tifton, 2000.* % control *2,4-D applied at 1 qt/A.

  29. Cutleaf Eveningprimrose Fresh Weights After Treating with Burndown Herbicides. Tifton, 2000.* Grams/plot *Fresh weights taken from 12 plants per plot. Roundup Ultra applied at 2 pt/A and 2,4-D at 1 pt/A.

  30. 2,4-D Burndown for Cotton(from fallow land section of labels) • No specific language concerning cotton • Do not plant any crop in treated fallow land until 3 months after treatment or until chemical has disappeared from soil

  31. Current Recommendations -- 2,4-D Burndown for Cotton • 1 pt/acre • Alone or Mixed with Glyphosate • Applied 45 days before planting • Research to date shows effectiveness and crop safety

  32. Cotton Injury from 2.1 mls Per Acre of 2,4-D. Tifton, 2000.

  33. Weeds Difficult to Control by Glyphosate?

  34. USE A DNA HERBICIDE

  35. Florida Pusley Control with Glyphosate and Glyphosate Tank Mixtures. Tifton, 2000.* 99 a 92 ab 87 bc 81 bc % control *Florida pusley 2 inches. Roundup UltraMAX applied at 1.25 pt; 2,4-D at 1 pt; Direx or Caparol at 1.5 pt.

  36. Weeds Difficult to Control by Glyphosate?

  37. Controlling Yellow and Purple Nutsedge? Nutsedge Control Programs: 1) 2 applications of glyphosate prior to 5th leaf followed by conventional chemistry including 2 lb ai MSMA directed 2) 1 application of glyphosate prior to 5th leaf followed by conventional chemistry including 2 lb ai MSMA directed 3) 2 applications of glyphosate 4) Zorial or Staple?????

  38. Yellow and Purple Nutsedge Control by Glyphosate. Greenhouse. 98 90 * 81 * 82 77 * 70 % control 42 42 Glyphosate (lb) *Purple nutsedge controlled significantly greater than yellow nutsedge. LSD=10

  39. Yellow and Purple Nutsedge Control by MSMA. Greenhouse. 82 * 69 61 % control 48 49 * 42 MSMA (lb) *Yellow nutsedge controlled significantly greater than purple nutsedge. LSD=10

  40. Weeds Difficult to Control by Glyphosate?

  41. Mid-Season Morningglory Control by Glyphosate & Glyphosate/Staple Mixtures. Moultrie, 2000. Pitted Smallflower morningglory morningglory Glyphosate 73 89 Glyphosate + Staple 93 97 Things to consider? 1. Morningglory size at time of application (5 inches here). 2. Will you post-direct with conventional chemistry or glyphosate?

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