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Gibberella Ear Rot

 
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Gibberella Ear Rot

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Symptoms of Gibberella Ear Rot

  • Gibberella Ear Rot is most readily identified by the red or pink color of the mold starting at ear tip
  • Mold may be very pale in some cases, causing it to be confused with other ear rots
    • Gibberella almost always begins at the ear tip and progresses from there
    • Fusarium is usually scattered throughout the ear or localized on injured kernels
    • Diplodia usually starts at the base of the ear, is gray rather than pink, and husks may be “bleached”
  • Early, severely infected ears may rot completely, with husks adhering tightly to the ear and the mold growing between the husks and ear
  • Perithecia, or black fungal fruiting structures, may be lightly attached to kernel surface

Facts on Gibberella Ear Rot

gibberella ear rot
  • Caused by the fungus Gibberella zeae
  • Infects other cereals – causes head scab of wheat
  • Overwinters in infected crop residue
  • Spores are spread from crop residue to corn ears by wind and rain splash
  • Infection of corn ears occurs through young silks
  • Infection favored by cool, wet weather during and after pollination (optimum temperature 65 to 70 F)
  • Often a problem in the northern and eastern Corn Belt (both U.S. and Canada)

Disease Cycle

Giberella ear rot disease cycle

Impact on Crop

Damaged corn kernels caused by gibberella ear rot.
  • Fungus consumes grain dry matter
    • Yield is reduced
    • Test weight is lower, which may reduce grain grade and price/bu
  • Fungus lowers grain quality
    • Grain may be downgraded for damaged kernels, reducing price/bu
      • Maximum limits for damaged kernels are 5% for No. 2, 7% for No. 3 and 10% for No. 4 yellow corn
    • Grain storage life may be greatly reduced
    • Grain may be inferior or unsuitable for many feed and food uses and ethanol production if mycotoxins are produced
Mycotoxins May or May Not Occur
  • Deoxynivalenol (DON), also called vomitoxin
    • Causes feed refusal and poor weight gain in livestock, especially swine
  • Zearalenone - Occurs much less frequently than DON
  • Mycotoxin contamination of grain may or may not accompany ear mold symptoms

Management of Gibberella Ear Rot

Hybrid selection

  • Pioneer corn breeders have progressively improved hybrids
    • Selected for genetic tolerance in environments where disease occurs at high levels
    • Selected against husk tightness and ears that remain upright after maturity
    • Selected for hybrids with fast ear drydown
  • Pioneer provides ratings for its hybrids
    • Ratings range from 3 to 6 for most hybrids (9=resistant), indicating that high levels of resistance are not yet available in today’s hybrids
    • If Gibberella ear rot caused significant damage in the past, consider planting only hybrids with at least a moderate rating (5 or higher)

Rotate to a non-host crop and manage crop residue

Scout fields before harvest in order to make informed decisions about harvest timing, postharvest grain handling, storage and utilization

  • Harvest infected fields early to limit disease development
  • Set combine to reduce kernel damage and remove lightest kernels
  • Dry infected grain at high temperature to a moisture of 15% or less
  • Monitor grain in storage to maintain its condition
  • Test grain for presence of mycotoxins and manage accordingly
gibberella ear rot

 

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