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2007 Corn Weed Control Update

2007 Corn Weed Control Update. Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences - UGA. Changes in 2007 Pest Control Handbook. Added Sequence Added Expert

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2007 Corn Weed Control Update

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  1. 2007 Corn Weed Control Update Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences - UGA

  2. Changes in 2007 Pest Control Handbook • Added Sequence • Added Expert • Added generic metolachlors but still included the following warning: The generic formulations of metolachlor (Parallel, Stalwart, Me-Too-Lachlor) have not provided the same length of residual control of certain weeds as similar rates of Dual Magnum formulations in some UGA field trials. • Added Firestorm • Added rain-free periods • Added a burndown table for reduced tillage. • Added Propel • Post-harvest control rec's for tropical spiderwort • Table of metolachlor and s-metolachlor products • Added Callisto to POST section • Table for ALS/GR-resistant pigweed

  3. Burndown Control Options • glyphosate • Paraquat • Ignite (glufosinate) • tank-mixes with? • 2,4-D • atrazine • Need a clean seed-bed at planting

  4. Ryegrass Control - Burndown • Hard to kill with 1 shot • Option # 1 • Glyphosate @ 1.125 lb ae/A + atrazine @ 3 pts/A • Option #2 • Gramoxone Inteon @ 1.9 pts/A – 2 WBP fb Gramoxone Inteon @ 1.9 pts/A + atrazine @ 3 pts/A - planting • RR corn systems • Accent????

  5. Conventional or RR Systems?

  6. Conventional Systems • Atrazine still THE major player in any system • Prowl in cheap but ……. • One of my favorites is Accent + Atrazine • If Texas panicum is main problem • many Pre-mixes

  7. Why do you not want to spend the money on an Accent + Atrazine treatment in field corn? Data from 18 irrigated weed control trials conducted in Georgia from 2001-2006. At $2.00 to 3.00/bu, it only takes a 9 to 14 bu/A increase to pay for the treatment!!!

  8. Corn Yield Response to Various POST Herbicide Treatments a ab a a a d b e Average of 2 tests conducted in 2003 and 2004 (Tifton, Attapulgus) Where Texas panicum is the main weed problem Atrazine PRE @ 1.5 qt/A

  9. Conventional Weed Management SystemsMany Pre-Mixes Available • Bicep II Magnum (atrazine + Dual II Magnum) • Lariat/Bullet (atrazine + Lasso) • Lexar (atrazine + Dual Magnum + Callisto) • many others • preemergence • a good choice if many different weed species are present • need 0.5” of rainfall or irrigation within 7-10 days for activation

  10. Post-Directed Options for Field Corn • Evik • Gramoxone Inteon/Firestorm • Lorox/Linex • Aim • tropical spiderwort • pigweeds • morningglory

  11. Should you use the RR corn system? • advantages • Inexpensive • easy • Broad spectrum • Reduced drift concerns • No soil insecticide issues • disadvantages • No residual • over-reliance on a single product • Herbicide resistance concerns • Volunteer in other RR crops

  12. How would I use RR corn systems? • If you are unwilling to use a PRE application of atrazine or something else…. • 2 applications of glyphosate • 1st application: 21-28 DAP + atrazine (1.5-2.0 qt/A) • 2nd application: 35-40 DAP • Sequence (s-metolachlor + glyphosate) • Expert (s-metolachlor + atrazine + glyphosate) • Do not forget to include extra seed costs/A in your budgets! • Irrigated @ 30,000/A = $12-13.00/A • Dryland @ 18,000/A = $7-8.00/A

  13. Texas Panicum Control At Harvest with Single or Split Applications of Roundup WM - II Untreated Roundup WM @ 22 ozs/A 21 + 35 DAP Roundup WM @ 22 ozs/A 21 DAP CN-04-04 (Attapulgus)

  14. Corn Yield Response to Single or Split Applications of glyphosate (4.5 lb ae/gal) @ 22 ozs/A. Average of 7 locations (2003-06) DKC67-60RR

  15. Glyphosate Resistance Around the World (12 species) • rigid ryegrass (1996) • goosegrass (1997) • horseweed (2000) • Italian ryegrass (2001) • hairy fleabane (2003) • buckhorn plantain (2003) • common ragweed (2004) • giant ragweed (2004) • Palmer amaranth (2005) • common waterhemp (2005) • johnsongrass (2005) • wild poinsettia (2005) ** Can be found in the US

  16. 47 of 100 sites With Confirmed Resistance to glyphosate!! 1 location in Lee County Confirmed in 2006 * 2005 GR-Pigweed Survey

  17. Preserving the Value of Glyphosate • tank-mix 2,4-D in burndown when glyphosate will be used in-crop • Consider paraquat or Ignite if appropriate • Alternate glyphosate use with other herbicide modes of action • Tank-mix with atrazine • Use other practices such as cultivation • Do not allow weed escapes to produce seed

  18. New Products that have been tested

  19. Syngenta • POST • 3 oz/A + COC + UAN or AMS ($13-15/A) • Up to 30” tall or 8-leaf corn • Palmer amaranth up to 5” • If 2,4-D is undesirable or ALS-resistance • Tank-mix with atrazine • also good on horsenettle • Interaction with OP’s

  20. Texas Panicum Control OR • About 30% of the time, Accent has provided better control of Texas panicum • But, yields have not been different.

  21. What about Liberty-Link Corn? • Glufosinate • Liberty (corn) • Ignite (cotton) • No tech fee • up to 24” tall corn or V7 • Tank-mix with atrazine • Liberty ATZ • good on morningglory, Texas millet, sicklepod • Hybrid performance??? • Garst 8353CB/LL, Hytest 7729Hx/LL 2007 Rebate Program * Up to $6.25/A

  22. Don’t Forget Liberty-Link Corn! 83 Bu/A 114 Bu/A Untreated Liberty 1.67SL @ 32 ozs/A Atrazine @ 90WG @ 1.0 lb/A AMS @ 3 lbs/A Applied 26 DAP CN-10-06 (Croplan Genetics 731 HX/LL) Ponder Farm 52 DAP

  23. Morningglory Control in Corn • as much atrazine as possible • 1.0 lb/A – PRE fb 1.5 lb/A – POST • small grain rotations • tank-mix with Aim (POST) • 2,4-D, Clarity • Liberty-Link Corn Systems • split applications of glyphosate (RR corn) * 1st application + atrazine

  24. Pigweed Control in Corn • preemergence • Atrazine • Dual/generics • Outlook • postemergence • Atrazine • Accent • Callisto • 2,4-D • Permit • Aim • glyphosate (RR corn) • Timing is critical!

  25. Sicklepod Control in Corn • Conventional Systems • Atrazine • 2,4-D • Clarity • Herbicide-Resistant • RR corn system • LL corn system

  26. Nutsedge Control • not very competitive • 800 plants/100 row feet only reduce yields by 2% • Eradicane or Sutan - PPI • Dual II Magnum or generic – PRE • Glyphosate – RR corn • Split applications • Basagran • Permit

  27. Tropical spiderwort (a.k.a. Benghal dayflower)Commelina benghalensis • tropical Africa native • annual or perennial • seeds and rhizomes • above and below ground flowers • 1,600 seeds/plant • alternate host of southern root-knot nematode • Reservoir for southern stem blight (white mold)

  28. TSW in Georgia * confirmed in 29 counties by GA Dept. of Ag and UGA in 2004(light blue) * identified in 4 more counties in 2005(black) *identified in 6 more counties in 2006 (dark blue)

  29. TSW Control in Field Corn • Depends on planting date • 2,4-D or Aim – POST • Sequence or Expert in RR corn • Aim/Gramoxone/Evik + Dual Magnum – layby • Post-harvest may be more important than in-crop • Tillage • 2 applications of 2,4-D, Gramoxone, or Aim

  30. Post-Harvest Control of Tropical Spiderwort Untreated 2,4-D @ 1.5 pt/A POST1 + POST 2 ($14.41/A) POST1: 8-10” tall COMBE POST2: 2 weeks later Photo 1 week after POST2

  31. Post-Harvest Control of Tropical Spiderwort Gramoxone Inteon @ 1 qt/A + COC POST1 + POST2 ($25.40/A) Untreated POST1: 8-10” tall COMBE POST2: 2 weeks later Photo 1 week after POST2

  32. Johnsongrass Control in Corn • Accent • no OP soil insecticide • hybrid tolerance to Accent • hybrid resistance to MDMV • Glyphosate in RR corn

  33. New Products Tested in 2006 • Impact (toprazamene) • Amvac • POST • Poor control of Texas panicum and sicklepod • Resolve (rimsulfuron) • DuPont • PRE and POST • Crop Injury problems • Stout (Accent + Harmony GT) • DuPont • POST • Crop Injury problems

  34. Resolve 25WG (rimsulfuron) Injury to Field Corn1.0 oz/A Applied PRE Pictures @ 18 DAT

  35. Stout Injury on Pioneer 3167 - 6 DAT CN-08B-06 Attapulgus, GA

  36. Future Products • KIH-485 • Kumiai • similar activity to Dual and Prowl but different structure and lower use rates • good on Palmer amaranth • Not yet been tested in Georgia Source: Steele et al. 2005. Weed Technology 19:866-869

  37. www.gaweed.com

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