1. Managing glyphosate-resistant Palmer amaranth in Liberty Link ® cotton. A.W. MacRae 1, A.S. Culpepper 1, and J.M. Kichler 2 1 Crop and Soil Sciences Department University of Georgia, Tifton, GA 2 Southwest District - CES University of Georgia

2. Glyphosate-resistant Palmer amaranth Glyphosate resistant Palmer amaranth has been found in 4 counties in Georgia. There was 144,330 acres planted in these counties in 2005 (Georgia/Publications/County_Estimates/2006/GaCotton.pdf) Roundup Ready technology is used on 98% of Georgia’s acreage

3. WMax 22 oz EPOST, 0.5” WMax 22 oz MPOST, 3” WMax 22 oz LPD, 10”

4. Objective Determine the efficacy of Liberty Link cotton weed management systems for control of glyphosate-resistant Palmer amaranth

5. Experimental Design Randomized complete block design with 4 replications. Cultivar used: FM 988 LLBR 4 row plots –Center two rows used for data collection Data collected –Weed efficacy –Cotton yield

6. Non-treated

7. Treatments 1 st Set 1)PRE – Prowl H 2 O (2 pt/A) POST – Ignite 280 (23 oz/A), 3 to 4-lf cotton 2)PRE POST – Ignite 280 (29 oz/A), 3 to 4-lf cotton POST – Ignite 280 (29 oz/A), 11-lf cotton 3)PRE POST – Ignite 280 (29 oz/A), 4 to 5-lf cotton POST – Ignite 280 (29 oz/A), 11-lf cotton Layby – MSMA (2.7 pt/A) + Direx (2 pt/A) + NIS (0.25% v/v)

8. Palmer amaranth control (30 DBH) Layby = MSMA + Direx + NIS

9. Ignite (23 oz) at 5 inch Direx + MSMA PD

10. Ignite (23 oz) at 2 inch Direx + MSMA PD

11. Prowl PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

12. Seed Cotton Yield Layby = MSMA + Direx + NIS

13. Treatments 2 nd Set 1)PRE – Prowl H 2 O (2 pt/A) POST – Ignite 280 (29 oz/A), 3 to 4-lf cotton 2)PRE – Prowl H 2 O (2 pt/A) POST – Ignite 280 (23 oz/A) + Staple LX (1.7 oz/A), 3 to 4-lf cotton 3)PRE – Prowl H 2 O (2 pt/A) POST – Ignite 280 (23 oz/A) + Dual Magnum (1 pt/A), 3 to 4-lf cotton 4)PRE – Prowl H 2 O (2 pt/A) POST – Ignite 280 (23 oz/A), 3 to 4-lf cotton POST – Ignite 280 (23 oz/A), 11-lf cotton Layby – MSMA (2.7 pt/A) + Direx (2 pt/A) + NIS (0.25% v/v)

14. Palmer amaranth control (30 DBH) PRE = Prowl H 2 O POST = Ignite applied to 3 to 4-lf cotton Layby = MSMA + Direx + NIS

15. Prowl PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

16. Prowl PRE Ignite (29 oz) at 2 inch Direx + MSMA PD

17. Prowl PRE Ignite (23 oz) + Staple at 2 inch Direx + MSMA PD

18. Prowl PRE Ignite (23 oz) + Dual Mag. at 2 inch Direx + MSMA PD

19. Prowl PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

20. Seed Cotton Yield PRE = Prowl H 2 O POST = Ignite applied to 3 to 4-lf cotton Layby = MSMA + Direx + NIS

21. Treatments 3 rd Set 1)PRE – Prowl H 2 O (2 pt/A) + Reflex (1 pt/A) POST – Ignite 280 (23 oz/A), 3 to 4-lf cotton 2)PRE – Prowl H 2 O (2 pt/A) + Reflex (1 pt/A) POST – Ignite 280 (23 oz/A) + Staple LX (1.7 oz/A), 3 to 4-lf cotton 3)PRE – Prowl H 2 O (2 pt/A) + Reflex (1 pt/A) POST – Ignite 280 (23 oz/A) + Dual Magnum (1 pt/A), 3 to 4-lf cotton Layby – MSMA (2.7 pt/A) + Direx (2 pt/A) + NIS (0.25% v/v)

22. Palmer amaranth control (30 DBH) PRE = Prowl H 2 O POST = Ignite applied to 3 to 4-lf cotton Layby = MSMA + Direx + NIS

23. Prowl PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

24. Prowl + Reflex PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

25. Prowl + Reflex PRE Ignite (23 oz) + Staple at 2 inch Direx + MSMA PD

26. Seed Cotton Yield PRE = Prowl H 2 O POST = Ignite applied to 3 to 4-lf cotton Layby = MSMA + Direx + NIS

27. Treatments 4 th Set 1)PRE – Prowl H 2 O (2 pt/A) + Cotoran (2.5 pt/A) POST – Ignite 280 (23 oz/A), 3 to 4-lf cotton 2)PRE – Prowl H 2 O (2 pt/A) + Cotoran (2.5 pt/A) POST – Ignite 280 (23 oz/A) + Staple LX (1.7 oz/A), 3 to 4-lf cotton 3)PRE – Prowl H 2 O (2 pt/A) + Cotoran (2.5 pt/A) POST – Ignite 280 (23 oz/A) + Dual Magnum (1 pt/A), 3 to 4-lf cotton Layby – MSMA (2.7 pt/A) + Direx (2 pt/A) + NIS (0.25% v/v)

28. Palmer amaranth control (30 DBH) PRE = Prowl H 2 O POST = Ignite applied to 3 to 4-lf cotton Layby = MSMA + Direx + NIS

29. Prowl PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

30. Prowl + Cotoran PRE Ignite (23 oz) at 2 inch Direx + MSMA PD

31. Seed Cotton Yield PRE = Prowl H 2 O POST = Ignite applied to 3 to 4-lf cotton Layby = MSMA + Direx + NIS

32. Summary 1) Timing of Ignite 280 application is more important that rate of Ignite 280 used. 2) Palmer amaranth must not be greater than 2 inches in height to achieve optimum control. 3) Applying Prowl H 2 O PRE produced 220 lbs more seed cotton than a second application of Ignite 280 with no PRE.

33. Summary 4) The addition of Dual Magnum POST or a second shot of Ignite 280 provided 11-12% greater Palmer amaranth control (30 DBH) and 350-380 lbs more seed cotton. 5) The addition of Reflex or Cotoran PRE provided 18-22% greater Palmer amaranth control (30 DBH) and 290-320 lbs more seed cotton. Based on: PRE = Prowl H2O POST = Ignite 280 at 2 in Palmer, 3 to 4-lf cotton LAYBY = MSMA + DIREX + NIS

34. Summary 6) The addition of Dual Magnum or Staple POST to applications of Prowl H 2 O + Cotoran or Reflex PRE provided no benefit. Based on: PRE = Prowl H2O POST = Ignite 280 at 2 in Palmer, 3 to 4-lf cotton LAYBY = MSMA + DIREX + NIS

35. Conclusions 1) Ignite 280 must be applied timely. 2) Preemergence a) Yellow herbicide + Reflex b) Yellow herbicide + Cotoran c) Yellow herbicide + Direx 3) Postemergence a) Ignite + Dual Magnum b) Ignite – 2 applications 4) Layby - MSMA + Direx, Valor, Layby Pro, or Suprend

36. Prowl PRE, Roundup POST TwiceProwl PRE, Ignite POST Twice

37. 2006 Georgia OVT

38. Support for this project and my PAYCHECK has been provided by Georgia Cotton Commission Cotton Incorporated BASF Bayer Dupont Monsanto Syngenta Valent

39. Questions? Andrew W. MacRae Post Doctoral Research Associate Department of Crop and Soil Sciences University of Georgia, Tifton, GA UGA Weed Science Website: www.gaweed.com