Ear Rot Identification

Aspergillus ear rot

The fungus that causes Aspergillus ear rot produces a dusty, olive-green growth on kernels. This growth is usually first noticed at the tip of the ear, but can be found on any part of the ear.

Aspergillus Figure
Aspergillus ear rot in corn
Photo credit: Burt Bluhm
Conditions favoring disease/mycotoxin development

Aspergillus ear rot is common when hot, dry conditions occur during pollination and grain fill. Late-planted corn is more at risk for Aspergillus ear rot since it pollinates later in the summer when temperatures are typically higher. Aflatoxin develops when drought and high temperatures occur, and especially when the overnight temperature is above 80 °F

Scouting tips

Symptoms appear first in dry or drought-stressed areas such as hillsides and sandy soils. In areas of the U.S. where corn is irrigated (such as the Mississippi Delta region) symptoms will appear where irrigation is limited, such as in dry edges of fields, or dry areas where the center pivot does not reach.

For more information on Aspergillus ear rot read the following:

Diplodia ear rot

Fig2
Diplodia ear rot of corn
Photo credit: Charles Woloshuk

Bleached husks on green plants are the first symptom of Diplodia ear rot. Affected ears will have a white fungal growth on kernels. The fungus typically forms a mat of growth and husks can stick to the ear. In some instances, ears and kernels will be lightweight, and kernels will turn gray or brown.

Conditions favoring disease development

Moderate temperatures and wet weather during silking and grain fill favor Diplodia ear rot development. Wet conditions at harvest or delayed harvest allow the fungus to continue to spread in ears. Planting susceptible hybrids, planting into fields with high levels of corn residue and planting corn following corn all increase the risk of disease development.

Scouting tips

Scout fields as corn reaches maturity and look for bleached husks and white mold at the base of the ear.

For more information on Diplodia ear rot read the following:

Fusarium ear rot

White or purple fungal growth can be observed on scattered kernels throughout the ear. Infected kernels may be gray or brown, and/or have white streaks in the kernel known as a “starburst” pattern. The rot is often at and around sites of insect damaged kernels.

IMG_0788
Fusarium ear rot
Photo credit: Burt Bluhm
Conditions favoring disease/mycotoxin development

Moderate to warm temperatures during silking favor Fusarium ear rot and fumonisin production. The ear rot is linked with insect feeding and mechanical damage, and damaged ears will be at higher risk for ear rot and fumonisin contamination. Delayed harvest allows the fungus to continue to spread in ears.

Scouting tips

Scout fields as corn reaches maturity and look for ears with insect damage and scattered mold on ears.

For more information on Fusarium ear rot read the following:

Gibberella ear rot

Red or pink rot develops at the tip of the ear. The fungus forms a mat of fungal growth on the ear, causing the husk to stick to the ears and silks. Husks may bleach prematurely and have a pink color. In some cases the pink fungal growth can appear white, which may cause misidentification as Diplodia ear rot.

Fig_2_Gib
Gibberella ear rot
Photo credit: Charles Woloshuk 
Conditions favoring disease/mycotoxin development

Cool, wet weather during early silking favors Gibberella ear rot and mycotoxin production. Fields with high levels of corn or small grain residues or corn following corn may be at higher risk for disease development. Delayed harvest allows the fungus to continue to spread in ears.

Scouting tips

Scout fields as corn reaches maturity and look for ears with bleached husks and pink mold at the tips of ears.

For more information on Gibberella ear rot read the following:

Penicillium ear rot

Pennicillium ear rot
Penicillium ear rot
Photo credit: Tom Isakeit

Blue-green powdery growth on and between kernels. Penicillium ear rot is typically found on ears that have been injured, either mechanically or by insects. Colonized kernels can appear streaked and bleached, and if the moldy growth gets into the kernel embryo it causes blue-eye of corn. Fungal growth usually appears at the ear tip, but can also be found on portions that have been injured. Several Penicillium species can cause Penicillium ear rot, but not all of them are able to produce mycotoxins.

Conditions favoring disease/mycotoxin development

Wet, humid conditions post grain-fill favor infection by Penicillium species. Ears damaged by insect feeding or mechanical damage will be more susceptible to infection. The fungus will also be able to continue to spread in grains stored above 17% moisture.

Scouting tips

Scout fields as corn reaches maturity and look for blue-green, powdery growth on and between the kernels of ears, particularly those with insect damage.

For More information on Corn ear rot identification visit:

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