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Managing Tropical Spiderwort With Sequential Dual Applications During 2005

Managing Tropical Spiderwort With Sequential Dual Applications During 2005. T. Flanders, A. S. Culpepper, W. Duffie, and A. C. York Univ. of Georgia and N. C. State. Tropical Spiderwort in Georgia. 1999. 2004. 2004 map confirmed by the GA Dept of Ag. Blue = 2004 sites confirmed

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Managing Tropical Spiderwort With Sequential Dual Applications During 2005

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  1. Managing Tropical Spiderwort With Sequential Dual Applications During 2005 T. Flanders, A. S. Culpepper, W. Duffie, and A. C. York Univ. of Georgia and N. C. State

  2. Tropical Spiderwort in Georgia 1999 2004 2004 map confirmed by the GA Dept of Ag

  3. Blue = 2004 sites confirmed Black = 2005 sites confirmed

  4. Why Does Tropical Spiderwort Continue to Spread Through Georgia? • Emergence pattern

  5. In Georgia, 1105 plants per meter square emerged after early June. Webster, 2004

  6. August 1 emergence after controlling 10 days earlier

  7. Why Does Tropical Spiderwort Continue to Spread Through Georgia? • Emergence pattern • Lack of residual herbicides

  8. 1.0 X none 1.5 X none 2.0 X none 3.3 X none Spiderwort Response to Roundup* *Pictures 15 d after treatment. No plants died from any treatment. Six inch at time of application.

  9. Why Does Tropical Spiderwort Continue to Spread Through Georgia? • Emergence pattern • Lack of residual herbicides • Lack of tillage

  10. Estimated Glyphosate-Resistant Planted Acres. % Acres

  11. The Benefits from Reduced Tillage Currently Outweigh the Troubles of Tropical Spiderwort (at least for the short term)!

  12. Objectives • Determine the most effective application rates and timings for Dual Magnum • Determine the most effective layby treatment

  13. Materials and Methods • DP 555 BRR Cotton • 2004 and 2005 • Planted early May • RCB design • Four rows by 25 feet • Four replications * Cairo

  14. Application Information • Treatments applied at 15 GPA and 3 MPH • Tropical spiderwort 1 to 5 inches, avg. 2 to 3 inch • 225 per sq. yard • Weed control visually estimated throughout season

  15. Exp 1: Most Effective Use of Dual* 4-5 leaf** 12 leaf directed • RU RU • RU + Dual 16 oz RU • RU RU + Dual 16 oz • RU + Dual 8 oz RU + Dual 8 oz • RU + Dual 12 oz RU + Dual 12 oz • RU + Dual 16 oz RU + Dual 16 oz *Prowl PRE applied over trial area; RU = WeatherMax 22 oz/A. Dual = Dual Magnum.

  16. Dual PRE not labeled on Georgia Soils Dual Magnum PRE

  17. 89a 86ab 81b 69c 67c % 53d RU R+D16 R R+D8 R+D12 R+D16 4 leaf 12 leaf RU R R+D16 R+D8 R+D12 R+D16 Tropical Spiderwort Control at Late-Season. Grady County, Averaged over 2004 and 2005.* *Prowl PRE over trial area.

  18. Control 17 Days After Layby. Non-treated Control RU EPOT fb RU Layby

  19. Tropical Spiderwort Size at Time of Layby Application Roundup Roundup + Dual

  20. Control 17 Days After Layby. RU EPOT fb RU + Dual Layby RU + Dual EPOT fb RU Layby

  21. Control 17 Days After Treatment. RU + Dual 12 oz Sequentially RU + Dual 8 oz Sequentially

  22. 13a % 7 b 0 c 6 b RU R+D8 R+D12 R+D16 4 leaf RR Visual Cotton Response to Herbicide Treatments 4 d, Avg over 2004 and 2005.* *Prowl PRE over trial area.

  23. Exp 2: Most Effective Layby Option* Factorial of • RU • RU + Aim (1.5 oz) • RU + Valor (1 oz) • MSMA + Direx (2 pt) • MSMA + Valor (2 oz) • No Dual Magnum • Dual Magnum 16 oz/A *Prowl PRE, Roundup + Dual Magnum 12 oz EPOT; RU = WeatherMax 22 oz/A; MSMA = 2 lb ai/A.

  24. Percent Tropical Spiderwort Control at 9 d after Layby. Avg. over 2004 and 2005* *Prowl PRE followed by Roundup + Dual Mag (12 oz) EPOST.

  25. Percent Tropical Spiderwort Control at at Harvest. Avg. over 2004 and 2005* *Prowl PRE followed by Roundup + Dual Mag (12 oz) EPOST.

  26. Percent Tropical Spiderwort Control at at Harvest. Avg. over 2004 and 2005* *Prowl PRE followed by Roundup + Dual Mag (12 oz) EPOST.

  27. Summary • Sequential applications of Dual Magnum are more effective than single applications. • Control by sequential applications tended to be greater with Dual Magnum rates of 12 to 16 oz. • Layby applications of Roundup or MSMA plus Valor or Direx as well as Roundup plus Aim offer growers effective burndown of emerged plants at layby

  28. Summary • Dual Magnum will be needed with layby applications in heavily infested fields. • Current labels are prohibitive for mixing Dual Magnum with several of these options. • Programs will be costly and if it don’t rain it don’t work. • If it rains too much, the Dual Magnum may last less than 3 weeks.

  29. QUESTIONS?

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