• 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

• 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)

• 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

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