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Fundamentals of Corn Pathology

Fundamentals of Corn Pathology. Paul Vincelli University of Kentucky. Disease triangle. What are some factors that favor disease development in KY corn production?. Corn residue can favor certain diseases. Spores of gray leaf spot fungus. What is the most practical way to kill out

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Fundamentals of Corn Pathology

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  1. Fundamentals of Corn Pathology Paul Vincelli University of Kentucky

  2. Disease triangle What are some factors that favor disease development in KY corn production?

  3. Corn residue can favor certain diseases Spores of gray leaf spot fungus What is the most practical way to kill out pathogens surviving in corn residue?

  4. Almost all disease management in corn is preplant.

  5. Leaf diseases

  6. Gray leaf spot

  7. Gray leaf spot Hybrid differences Leaf blighting

  8. Northern leaf blight Image by K. Leonard and E. G. Suggs Courtesy of the American Phytopathological Society

  9. Large, coalescing lesions of NLB

  10. Susceptible and resistant reactions to Northern leaf blight Susceptible hybrid Chlorotic lesion Reaction (Ht resistance) Image by K. Leonard and E. G. Suggs Courtesy of the American Phytopathological Society

  11. NLB: Susceptible vs Ht resistance

  12. NLB: susceptible (R) vs Ht resistance (L) Henderson County, 2004

  13. Lodging from Severe NLB Courtesy Bill Meachum, Pioneer

  14. Rusts Common rust Rust spores Southern rust Common rust

  15. Brown spot

  16. Purple leaf sheath

  17. Holcus spot

  18. Infection of foliage by bacteria Fire blight

  19. Stalk rots

  20. Anthracnose lower stalk rot in mature plants

  21. Anthracnose top dieback G. Munkvold

  22. Diplodia stalk rot

  23. Gibberella stalk rot

  24. Gibberella (left) and Diplodia (right) stalk rots

  25. Stalk rot = disintegration of pith Charcoal stalk rot

  26. Factors that EnhanceCorn Stalk Rots High plant populations High nitrogen rates High levels of leaf disease

  27. High-yield production can favor stalk rots

  28. Seedling diseases

  29. Pythium damping off Karen Rane, Purdue U. Data of Woltz and TeKrony

  30. Anthracnose in seedlings

  31. Other Diseases

  32. Common Smut

  33. Maize dwarf mosaic

  34. Maize chlorotic dwarf virus

  35. Crazy top

  36. Ear and kernel rotsMycotoxins

  37. Diplodia fungus

  38. Diplodia ear rot

  39. Fusarium ear rot: Fumonisins

  40. Gibberella ear rot Produces zearalenone and DON

  41. Aspergillus ear rot: Aflatoxins

  42. Extension publications on mycotoxins

  43. Maximum Fumonisin Levels Recommended by US FDA

  44. Corn with 26 ppm fumonisins

  45. FDA Aflatoxin Action Levels *Exceptions for breeding cattle, breeding swine, mature poultry, finishing swine, & finishing beef cattle

  46. Factors That Enhance Corn Ear and Kernel Rots and Preharvest Mycotoxin Accumulation • Hot, dry weather during silking or grain fill • Delayed harvest • Injury to kernels (insects, birds) • Hybrids with ears at maturity that are: - upright - incomplete husk coverage

  47. Crop stress can favor preharvest mycotoxin contamination • Fusarium ear rot • Aspergillus ear rot

  48. Harvest management can influence postharvest accumulation of mycotoxins

  49. Reducing risks of mycotoxins in storage • Adjust combine for minimum kernel damage • Dry below 15.5% within 24-48 hours of shelling • Clean storage facilities and control insects • Aerate and check for heating and crusting

  50. Testing corn samples UK Grain Quality Testing Lab Attn: Michael D. Montross  Biosystems & Agricultural Engineering 128 Barnhart Bldg.  University of Kentucky Lexington, KY  40546-0276 Voice: (859) 257-3000 X106 Fax: (859) 257-5671 Email: montross@baeuky.edu

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