1. Response of Glyphosate-Resistant Palmer Amaranth to Thirteen Residual Herbicides Jeremy Kichler

2. The Objective of this Study was to Determine The Most Effective Residual Herbicides for Use in Cotton 1. At planting 2. Postemergence 3. Layby

3. Two Locations in 2006 Macon County, Georgia Robeson County, North Carolina

4. Methods Plot Size – 6 feet by 22-25 feet Conventional Tillage All herbicides applied to soil without debris

5. Planting Dates and Rainfall Planting/Application Dates May 1, 2006 – Macon County, GA May 24, 2006 – Robeson County, NC Factorial treatment 13 herbicides 2 herbicide rates 4 replications

6. Herbicide Treatments and 1X Rates Caparol (2 pt) Cotoran (2 pt) Direx (2 pt) Dual Magnum (1 pt) Envoke (0.1 oz) Layby Pro (2 pt) Linex (2 pt) Prowl H2O (2 pt) Reflex (1 pt) Stalwart (1 pt) Staple LX (1.7 oz) Suprend (1.0 lb) Valor SX (1.5 oz) All treatments were applied at 1X and 1.5X rates

7. Data Reporting Data from both GA and NC reported by location at two evaluation dates Rate main effect significant Herbicide treatment main effect significant

8. Percent Palmer Control Averaged Over Herbicide Treatments, 18-26 DAT. RateGANC 1 X8977 1.5 X9387 LSD23

9. RateGANC 1 X7458 1.5 X8368 LSD45 Percent Palmer Control Averaged Over Herbicide Treatments, 31-36 DAT.

10. Herbicide Options Caparol Cotoran Direx Prowl Reflex Staple Direx Layby Pro Linex Suprend Valor SX Dual Mag. Envoke Stalwart Staple At-PlantingPOSTLayby

11. LSD: GA = 6; NC = 6 *Data pooled over two rates. Percent Palmer Control by PRE Applied Residual Herbicides. 18-26 DAT.* 79 97 83 61 87 98 88 91 8182 85 70

12. *Data pooled over rates. Palmer Amaranth Control by PRE Applied Residual Herbicides. 31-36 DAT.* LSD: GA = 10; NC = 13 59 90 59 23 71 99 73 80 64 67 43

13. Planting Dates and Rainfall Rainfall: GANC week 14.5 in0.4 in week 2-30 in2.99 in week 4-50 in2.08 in

14. Non-treated GA

15. 115 ReflexStaple GA

16. ProwlCaparol GA

17. 115 ReflexStaple NC

18. ProwlCaparol NC

19. *Data pooled over rates. Palmer Amaranth Control by POST Applied Residual Herbicides. 18-26 DAT.* LSD: GA = 6; NC = 6 97 86 79 88 86 97 88 90

20. *Data pooled over rates. Palmer Amaranth Control by POST Applied Residual Herbicides. 31-36 DAT.* LSD: GA = 10; NC = 13 89 63 56 67 64 90 73 74

21. StalwartDual Mag. GA

22. Palmer Amaranth Control by Layby Applied Residual Herbicides. 18-26 DAT.* *Data pooled over rates. LSD: GA = 6; NC = 6 91 81 92 73 97 95 99 96 81

23. Palmer Amaranth Control by Layby Applied Residual Herbicides. 31-36 DAT.* *Data pooled over rates. LSD: GA = 10; NC = 13 80 84 63 69 59 92 83 99 85 64

24. ValorDirex GA

25. Conclusions At-Planting Options -- Reflex or Staple Topical Options -- Staple or Dual Magnum Layby Directed Options -- Suprend or Valor

26. Conclusions Caution with Staple and Suprend due to growing occurrences of ALS inhibitor resistance. In fields without ALS resistance we recommend only 1 application of an ALS herbicide per season.