Slide Presentation

TITLE    (click title to view slides)
Corn Weed Management for 'New' County Extension Agents

AUTHOR
Eric P. Prostko
Extension Weed Specialist
Department of Crop & Soil Sciences - UGA

DOWNLOAD
• Slide Presentation (PowerPoint, 11.9 MB)
• PowerPoint Viewer from Microsoft

TABLE OF CONTENTS
  1. Corn Weed Management for 'New' County Extension Agents
  2. Cultural Practices
  3. Mechanical Cultivation
  4. Insecticide/Herbicide Interactions
  5. Weed/Disease Interactions
  6. Corn Stages of Growth
  7. Specific Herbicides
  8. Atrazine Use in Field Corn
  9. Conventional Weed Management Systems - Many Pre-Mixes Available
  10. Prowl Use in Field Corn
  11. Optimum Prowl/Pendimax Timing - Field Corn
  12. Prowl Injury in Field Corn
  13. Accent Use in Field Corn
  14. Corn Hybrid/Herbicide Tolerance
  15. Why do you not want to spend the money on an Accent + Atrazine treatment in field corn?
  16. Know Your Grasses
  17. Texas Panicum vs. Crabgrass
  18. Post-Directed Applications
  19. Post-Directed Options for Field Corn
  20. Herbicide Resistant Corn Technologies
  21. Should you use the RR corn system?
  22. How would I use RR corn systems?
  23. Texas Panicum Control At Harvest with Single or Split Applications of Roundup WM - II
  24. Corn Yield Response to Single or Split Applications of glyphosate
  25. What about Liberty-Link Corn?
  26. Don’t Forget Liberty-Link Corn!
  27. Clearfield Corn Systems
  28. Common Weed Problems
  29. Texas Panicum Control in Corn - What works!
  30. Texas Panicum Control
  31. Texas Panicum Control (104 DAT) - II: Accent vs Option - 2004
  32. Sicklepod Control in Corn
  33. Pigweed Control in Corn
  34. Morningglory Control in Corn
  35. Nutsedge Control
  36. Johnsongrass Control in Corn
  37. Tropical spiderwort (a.k.a. Benghal dayflower) Commelina benghalensis
  38. TSW in Georgia
  39. TSW Control in Field Corn
  40. Reduced Tillage Systems
  41. Burndown Control Options
  42. Ryegrass Control - Burndown
  43. Herbicide-Resistant Weed Issues
  44. Herbicide Resistance - Definition
  45. Glyphosate Resistance Around the World (12 species)
  46. Confirmed Glyphosate-Resistant Palmer Sites
  47. What does ALS mean?
  48. Commonly Used ALS Herbicides
  49. ALS-Resistant Palmer Amaranth Survey
  50. Where to go for more information?



SLIDE CONTENTS
  1. Corn Weed Management for 'New' County Extension Agents Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences - UGA April 2007
  2. Cultural Practices Planting Date Row Spacing Fertility give the crop a competitive edge against weeds
  3. Mechanical Cultivation Time Diesel fuel prices Strip-tillage
  4. Insecticide/Herbicide Interactions Insecticides Organophosphates (OP’S) Counter, Lorsban, Thimet Herbicides Accent, Beacon, Option, Callisto, Steadfast, Basis
  5. Weed/Disease Interactions Maize Dwarf Mosaic Virus (MDMV) Maize Chlorotic Dwarf Virus (MCDV) johnsongrass aphid/leafhoppers Accent/Beacon hybrid tolerance
  6. Corn Stages of Growth
  7. Specific Herbicides Atrazine Prowl Accent
  8. Atrazine Use in Field Corn Since 1958 foundation inexpensive excellent crop tolerance PPI, PRE, POST (12”) broad-spectrum up to 2.5 lb ai/A/year easily tank-mixed weak on T. panicum does not last full season in SE
  9. Conventional Weed Management Systems Many 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. Prowl Use in Field Corn since 1975 pendimethalin DNA or “yellow” inexpensive but…. do not apply PRE early-post (EPOST) up to 30” tall or V8 crop injury concerns Planting depth (1.5”) Furrow closure
  11. Optimum Prowl/Pendimax Timing Field Corn Prowl will not control emerged grasses!!!
  12. Prowl Injury In Field Corn Prowl Control
  13. Accent Use in Field Corn since 1991 nicosulfuron sulfonylurea ALS-inhibitor POST up to 20” tall or V6 20-36” (PDIR) Pigweed, Texas panicum Weak on crabgrass Hybrid sensitivity OP interaction Tank-mix with atrazine cost
  14. Corn Hybrid/Herbicide Tolerance Pioneer http://www.pioneer.com/CMRoot/Pioneer/usa/agronomy/corn/herb_table.pdf
  15. 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!!!
  16. Know Your Grasses large crabgrass johnsongrass fall panicum broadleaf signalgrass Source: SWSS Weed ID Guide
  17. Texas Panicum vs. Crabgrass WSSA Fringe of hairs membranous Texas panicum Southern crabgrass
  18. Post-Directed Applications
  19. Post-Directed Options for Field Corn Evik Gramoxone Inteon/Firestorm (paraquat) Lorox/Linex Aim tropical spiderwort pigweeds morningglory
  20. Herbicide Resistant Corn Technologies
  21. 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
  22. 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
  23. Texas Panicum Control At Harvest with Single or Split Applications of Roundup WM - II CN-04-04 (Attapulgus) Untreated Roundup WM @ 22 ozs/A 21 DAP Roundup WM @ 22 ozs/A 21 + 35 DAP
  24. 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
  25. 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 * Buy 20 gals and get a $5-6/A rebate
  26. Don’t Forget Liberty-Link Corn! 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 83 Bu/A 114 Bu/A
  27. Clearfield Corn Systems Not used that much or at all in Georgia Pursuit Lightning Pursuit + Arsenal POST Non-GMO ALS-resistance
  28. Common Weed Problems Texas panicum (Texas millet, buffalograss) sicklepod (coffeeweed) pigweeds morningglories nutsedges johnsongrass Tropical spiderwort (Benghal dayflower)
  29. Texas Panicum Control in Corn What works! Prowl/Pendimax (DPRE/EPOST) Accent (POST) Option (POST) RR or LL system post-directed * Evik/Paraquat
  30. Texas Panicum Control OR About 30% of the time, Accent has provided better control of Texas panicum But, yields have not been different.
  31. Texas Panicum Control (104 DAT) - II Accent vs Option - 2004 CN-04-04 (Attapulgus) Applied 21 DAP PANTE = 1-2”, 2-4 leaf Untreated Accent @ 0.67 ozs/A Agrioil @ 1% v/v Option @ 1.5 ozs/A MSO @ 1.25% v/v AMS @ 3 lbs/A
  32. Sicklepod Control in Corn Conventional Systems Atrazine 2,4-D Clarity Herbicide-Resistant RR corn system LL corn system
  33. Pigweed Control in Corn preemergence Atrazine Dual/generics Outlook postemergence Atrazine Accent Callisto 2,4-D Permit Aim glyphosate (RR corn) Timing is critical!
  34. 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, Status Liberty-Link Corn Systems split applications of glyphosate (RR corn) 1st application + atrazine Harvest Aids 2,4-D, sodium chlorate, glyphosate, Aim, paraquat
  35. 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
  36. Johnsongrass Control in Corn Accent no OP soil insecticide hybrid tolerance to Accent hybrid resistance to MDMV Glyphosate in RR corn
  37. 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)
  38. 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)
  39. 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
  40. Reduced Tillage Systems
  41. Burndown Control Options glyphosate Paraquat Ignite (glufosinate) tank-mixes with? 2,4-D atrazine Need a clean seed-bed at planting
  42. 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????
  43. Herbicide-Resistant Weed Issues Glyphosate ALS
  44. Herbicide Resistance Definition inherited ability of a weed or crop biotype to survive a herbicide application to which the original population was susceptible. Biotype = a group of plants within a species that has biological traits that are not common to the population as a whole.
  45. 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
  46. ** 3/15/2007
  47. What does ALS mean? Acetolactate synthase (ALS) Acetohydroxyacid synthase (AHAS) chloroplast enzyme needed to form certain amino acids Valine, leucine, isoleucine Herbicide families Imidazolinones Sulfonylureas Sulfonanalides benzoates
  48. Commonly Used ALS Herbicides 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
  49. ALS-Resistant Palmer Amaranth Survey
  50. Where to go for more information? UGA Weed Science Web-Site www.gaweed.com UGA Pest Control Handbook UGA Corn Production Guide