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Herbicide-Resistant Weeds: A Dilemma in Dixie

Herbicide-Resistant Weeds: A Dilemma in Dixie. Culpepper, York, Steckel, Prostko. What is Herbicide Resistance? (official WSSA definition). Inherited ability of a biotype of a weed to survive and reproduce following exposure to a dose of herbicide

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Herbicide-Resistant Weeds: A Dilemma in Dixie

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  1. Herbicide-Resistant Weeds: A Dilemma in Dixie Culpepper, York, Steckel, Prostko

  2. What is Herbicide Resistance? (official WSSA definition) Inherited ability of a biotype of a weed to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type.

  3. WeatherMax 22 oz, 2 d after application to 16 inch Palmer

  4. WeatherMax 33 oz/A on 3” Palmer

  5. Reported cases of herbicide-resistant weeds in US

  6. Why is Resistance Such a Big Deal Now?

  7. Why is Resistance Such a Big Deal Now? Significant 1. ALS resistant pigweeds • Glyphosate-resistant horseweed • Glyphosate-resistant ragweed • Glyphosate-resistant lambsquarters* • Glyphosate-resistant Italian ryegrass* Potentially Devastating 1. Glyphosate-resistant Palmer amaranth (pigweed) *suspected not confirmed

  8. ALS*-resistant Amaranthus species 99 99 02 98 93 93 96 00 93 98 94 92 91 94 95 02 97 94 00 *Imidazolinones, sulfonylureas, 19 states triazolopyrimidines, pyrimidinylthiobenzoates

  9. Accent Ally/Cimarron Beacon Beyond Cadre Classic Envoke Exceed Express Finesse FirstRate Glean Harmony Extra Maverick Pro Osprey Peak Permit Pursuit Python Scepter Staple Strongarm Commonly Used ALS Herbicides

  10. 2005 ALS-Resistant Pigweed Survey61 locations, 21 counties • 2892 plants treated • 2442 plants survived (84%) Prostko 2006

  11. Percent of cotton acreage planted to RR varieties. 20061 97 98 59 100 99 99 98 83 75 97 100 98 98 97 99 66 98 1USDA, AMS. 2006. Publ. mp-cn833.

  12. Adoption of Roundup Ready Technology in the US (million acres) Soybean 96 97 98 99 00 01 02 03 04 05 06 Cotton Corn 98 99 00 01 02 03 04 05 06 97 98 99 00 01 02 03 04 05 06

  13. Very Small Seeded Approximately 1 mm

  14. Altitude (ft) 230 460 Seeds found (#/1000 m3)* 3.3 1.7 Shields, E.J., J.T. Dauer, M.J. VanGessel, and G. Neuman. 2006. Horseweed (Conyza canadensis) seed collected in the planetary boundary layer. Weed Sci. 54:1063-1067. * Approximately 33 by 33 by 33 ft

  15. Must Start Clean! Photo credit: Larry Steckel

  16. Photo credit: Larry Steckel

  17. GR Horseweed Control Milan May 28, 2006 Burndown applied 4/3/06 Clarity 8 oz + Roundup WM 22oz 2,4-D 16 oz + Roundup WM 22oz Ignite 23 oz Roundup WM 22oz Clarity 8 oz + Roundup WM 22oz fb/Gramoxone Inteon 40 oz + Caparol 24oz Clarity 8 oz + Roundup WM 22oz fb/ Roundup WM 22oz + Cotoran 24oz LSD = 12 0 20 40 60 80 100 % Horseweed Control

  18. HORSEWEED • Preferred Burndown Options • Roundup + ½ pt Clarity, mid March • Roundup + 2 pt 2,4-D, mid March • With either of above, consider a residual herbicide with the burndown, such as Valor. • If no residual, Gramoxone + • Cotoran or Direx at planting • or Ignite + Cotoran or Direx • at planting.

  19. 2004 Common Horseweed Burndown Program Photo credit: Larry Steckel

  20. Rapid Growth Becoming Extremely Large

  21. 450,000 400,000 400,000 350,000 300,000 250,000 200,000 150,000 100,000 50,000 40,000 40,000 9,000 0 Palmer goosegrass annual common Amaranth bluegrass cocklebur Average Number of Seed Produced per Plant peanut - 175; cotton - 250; corn - 800 Top 4 Herbicide Resistant Weeds in US

  22. Multiple Generations – Short Seed Dormancy Attapulgus GA, September 2004

  23. Palmer Amaranth Infesting Cotton Untreated Glyphosate 4X rate, applied three times Georgia, 2006

  24. Palmer Amaranth Infesting Cotton Untreated Glyphosate 4X rate, applied three times North Carolina, 2006

  25. Cotton Yield vs. Palmer Competition 7%

  26. Glyphosate-resistant Palmer Amaranth Found 05 * * * 04 *Palmer populations being studied for resistance.

  27. Resistance trait will move through pollen

  28. Managing Glyphosate Resistance

  29. Georgia and North Carolina Recommendations* *Cultivation, Hooded Sprays, and/or Hand Weeding Will be Required

  30. Prowl H20 1.75 pt + Reflex 1 pt PRE WeatherMax 22 oz + Dual Mag 18 DAP before Pigweed emergence WeatherMax 22 oz + Direx 1.5 pt PDIR

  31. Prowl H20 1.75 pt + Reflex 1 pt PRE WeatherMax 22 oz + Dual Mag 24 DAP with ½” Palmer WeatherMax 22 oz + Direx 1.5 pt PDIR

  32. Prowl + Reflex PRE Roundup + Staple 3 inch Direx + MSMA PD

  33. Prowl H20 1.75 pt + Reflex 1 pt PRE WeatherMax 22 oz + Staple at 3 inch WeatherMax 22 oz + Direx 1.5 pt PDIR

  34. 2004 0 1.3 2.6 5.2 10.2 20.4 fl oz/A Staple LX 2006

  35. 1X glyphosate + 1X Staple; Palmer 0.5 inches when treated

  36. Delay the arrival or spread of resistance

  37. Resistance Management Practices • Reduce herbicide reliance (as practical) • 2. Diversify MOAs; Multiple MOAs • Multiple MOAs within a crop.

  38. DELAY glyphosate-resistant Palmer in RR cotton fields with LIGHT Palmer infestations* *Staple will not control ALS-resistant Palmer. Sequence can be used as the glyphosate + Dual mixture. Yellow = Prowl or Treflan type products.

  39. Resistance Management Practices • Reduce herbicide reliance (as practical) • 2. Diversify MOAs; Multiple MOAs • Multiple MOAs within a crop. • Crop rotation; different MOAs

  40. Resistance Management Practices • Reduce herbicide reliance (as practical) • Diversify MOAs; Multiple MOAs • Multiple MOAs within a crop. • Crop rotation; different MOAs • Detect resistance early

  41. Glyphosate-resistant Palmer amaranth: Georgia, 2005

  42. Detect Resistance Early

  43. How Bad Will Glyphosate-Resistant Palmer Amaranth Become? “This Palmer amaranth stuff makes me glad I am 18 months from retirement.” Dr. Alan York More on glyphosate-resistant Palmer? From 1:30 till 2:45 in Grand Ballroom C - distribution, pollen dispersal, and management

  44. Knowledge Gives Us Hope • Weed Resistance Learning Module at National Cotton Council Web Site: http://www.cotton.org/ • International Survey of Resistant Weeds * http://www.weedscience.org/in.asp • Cotton Incorporated is nearing completion of a Resistance Management Bulletin

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