Disease Facts
- •Caused by the fungus Gibberella zeae.
- •Overwinters in infected crop residue.
- •Spores are spread from residue to corn ears by wind and rain.
- •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 US and Canada).
- •Most common in continuous corn or corn following wheat that was infected with Fusarium head blight.
Disease Symptoms
- 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.
Mycotoxins
- Gibberella zeae can produce two mycotoxins in the infected kernels: deoxynivalenol and zearalenone.
- These mycotoxins can be harmful to many monogastric animals, especially swine.
- Mycotoxin contamination of grain may or may not accompany ear mold symptoms.
Management
- Scout fields before harvest in order to make informed decisions about harvest timing, postharvest grain handling, storage and utilization.
- Fields with significant infestations of Gibberella ear rot should be harvested as early as possible and handled separately.
- Set combine to reduce kernel damage and remove fines and shriveled or broken kernels.
- Dry infected grain at high temperature to a moisture of 15% or less and monitor grain in storage to maintain its condition.
- Test grain for presence of mycotoxins and manage accordingly.