Extension Circular 1901 (EC1901).
Under certain conditions, corn ear rot and grain mold diseases are common and can lead to loss of grain quality. Moldy grain can be docked or rejected at the elevator. Additionally, some ear and grain pathogens may produce secondary metabolites called mycotoxins, which are toxic to animals and humans consuming the contaminated grain. Mycotoxin-contaminated grain can also be docked or rejected. Mycotoxin production may start in the field and continue after harvest, or it may start during storage if mold infection begins there. When grain storage is necessary, drying grain to less than 15 percent moisture for long-term storage or to no more than 18 percent for short-term storage will help reduce fungal growth

Giesler, Loren J.

Harveson, Robert M.

Jackson-Ziems, Tamra A.

Korus, Kevin A.

Liu, Bo

Wegulo, Stephen N.

English

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnPapers in Plant Pathology Plant Pathology Department2012Corn Disease Profile III: Ear Rot Diseases andGrain MoldsTamra A. Jackson-ZiemsUniversity of Nebraska-Lincoln, tjackson3@unl.eduLoren J. GieslerUniversity of Nebraska-Lincoln, lgiesler1@unl.eduRobert M. HarvesonUniversity of Nebraska-Lincoln, rharveson2@unl.eduKevin A. KorusUniversity of Nebraska-Lincoln, kkorus@ufl.eduBo LiuUniversity of Nebraska, West Central Research and Extension CenterSee next page for additional authorsFollow this and additional works at: http://digitalcommons.unl.edu/plantpathpapersPart of the Other Plant Sciences Commons, Plant Biology Commons, and the Plant PathologyCommonsThis Article is brought to you for free and open access by the Plant Pathology Department at DigitalCommons@University of Nebraska - Lincoln. Ithas been accepted for inclusion in Papers in Plant Pathology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.Jackson-Ziems, Tamra A.; Giesler, Loren J.; Harveson, Robert M.; Korus, Kevin A.; Liu, Bo; and Wegulo, Stephen N., "Corn DiseaseProfile III: Ear Rot Diseases and Grain Molds" (2012). Papers in Plant Pathology. 541.http://digitalcommons.unl.edu/plantpathpapers/541AuthorsTamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Bo Liu, and Stephen N.WeguloThis article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/plantpathpapers/541EC1901Corn Disease Profile IIIEar Rot Diseases and Grain MoldsUNL Extension Plant Pathology TeamTamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson,  Kevin A. Korus, Bo Liu, and Stephen N. Wegulo2. Diplodia Ear Rot2a 2b1. Aspergillus Ear Rot14. Gibberella Ear Rot45. Penicillium Ear Rot5a 5b6. Cladosporium Ear Rot67. Moldy Outdoor Storage Pile7BB3. Fusarium Ear Rot3a 3bEar Rot Diseases and Grain MoldsUnder certain conditions, corn ear rot and grain mold diseases are common and can lead to loss of grain quality. Moldy grain can be docked or rejected at the elevator. Additionally, some ear and grain pathogens may produce secondary metabolites called mycotoxins, which are toxic to animals and humans consuming the contaminated grain. Mycotoxin-contaminated grain can also be docked or rejected. Mycotoxin production may start in the field and continue after harvest, or it may start during storage if mold infection begins there. When grain storage is necessary, drying grain to less than 15 percent moisture for long-term storage or to no more than 18 per-cent for short-term storage will help reduce fungal growth.Risk Factors and Stressful Conditions Favoring Ear Rot and Grain Mold Development• Moisture stress • Ear injury• Extreme weather conditions• Infected crop residue• Growing continuous corn• Susceptible hybrids• Damaged grain• High moisture storage conditionsDisease Description1.  Aspergillus Ear RotAspergillus flavus, A. parasiticus, Aspergillus spp.*Management: C, R, NMost common during years with high temperatures and drought conditions. Aspergillus spores tend to be yellow green to olive green (Figure 1) and infection is usually associated with the ear tips or other damaged areas such as those caused by insect feeding. These species, especially A. flavus, can produce the mycotoxin aflatoxin. 2. Diplodia Ear Rot Diplodia maydis (syn. Stenocarpella maydis)Management: C, R, NThick fungal mycelium evident of Diplodia ear rot most commonly develops at the base of the ear first (Figure 2a). Fungal reproductive structures (pycnidia) appear as small black dots on kernels (Figure 2b), cob, or husks. Advanced infections may overtake ears leading to development of lightweight mummy ears. The pathogen overwinters in infected crop residue and disease has been more common in minimum tillage and humid environments.3. Fusarium Ear RotFusarium verticillioides,  F. proliferatum, F. subglutinansManagement: C, R, NThis disease is common when crop stress occurs around silking. Infection can occur anywhere on the ear and can be associated with injury, such as caused by hail (Figure 3a). It may appear as white to pink cottony fungal growth (Figure 3b). Infected kernels may have a “starburst” pattern. Fusarium species may produce mycotoxins, including fumonisin, vomitoxin (DON), and/or zearalenone. 4. Gibberella Ear RotGibberella zeae (sexual stage of  F. graminearum)Management: C, R, NMost common in cool, humid conditions, it is closely related to the pathogen causing Fusarium ear rot. Symptoms typically develop as reddish mycelium and discoloration on the tips of ears (Figure 4) and may be accompanied by small black fungal reproductive structures (perithecia). Mycotoxins may include vomitoxin (DON) and zearalenone. 5. Penicillium Ear RotPenicillium spp.Management: C, NOften called “blue eye,” Penicillium ear rot develops most often on damaged ears and grain. The fungus produces large amounts of dusty blue-green spores (Figure 5). Penicillium species also can produce several less common mycotoxins. 6. Other Grain Molds Cladosporium Rot, Nigrospora Ear  or Cob Rot, Trichoderma Ear RotManagement: C, NAppearance and discoloration may vary by disease (Figure 6). Some may be more common after damage and premature plant death, such as following early frost, and can continue to grow during storage. Outdoor storage piles are especially at risk for grain mold development (Figure 7).Photo Credit: Figures 5a and 6 courtesy of Casey Schleicher and Amy Timmerman, respectively, University of Nebraska–Lincoln, and Figure 7 courtesy of Larry Ziems.*Management strategies which can be effective: C – cultural practices, such as the use of crop rotation, tillage, irrigation timing, or grain drying prior to storage may reduce disease; R – resistance: hybrids vary in their resistance/susceptibility and resistance to insects can reduce damage and disease severity ; N – management may not be necessary, practical, or possible.3. Gibberella Ear Rot4. Gibberella Ear Rot4. Charcoal Rot4bExtension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture.University of Nebraska–Lincoln Extension educational programs abide with the nondiscrimination policies of the University of Nebraska–Lincoln and the United States Department of Agriculture.© 2012, The Board of Regents of the University of Nebraska on behalf of the University of Nebraska–Lincoln Extension.  All rights reserved.

Corn Disease Profile III: Ear Rot Diseases and Grain Molds

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University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Papers in Plant Pathology Plant Pathology Department
2012
Corn Disease Profile III: Ear Rot Diseases and
Grain Molds
Tamra A. Jackson-Ziems
University of Nebraska-Lincoln, tjackson3@unl.edu
Loren J. Giesler
University of Nebraska-Lincoln, lgiesler1@unl.edu
Robert M. Harveson
University of Nebraska-Lincoln, rharveson2@unl.edu
Kevin A. Korus
University of Nebraska-Lincoln, kkorus@ufl.edu
Bo Liu
University of Nebraska, West Central Research and Extension Center
See next page for additional authors
Follow this and additional works at: http://digitalcommons.unl.edu/plantpathpapers
Part of the Other Plant Sciences Commons, Plant Biology Commons, and the Plant Pathology
Commons
This Article is brought to you for free and open access by the Plant Pathology Department at DigitalCommons@University of Nebraska - Lincoln. It
has been accepted for inclusion in Papers in Plant Pathology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.
Jackson-Ziems, Tamra A.; Giesler, Loren J.; Harveson, Robert M.; Korus, Kevin A.; Liu, Bo; and Wegulo, Stephen N., "Corn Disease
Profile III: Ear Rot Diseases and Grain Molds" (2012). Papers in Plant Pathology. 541.
http://digitalcommons.unl.edu/plantpathpapers/541
Authors
Tamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Bo Liu, and Stephen N.
Wegulo
This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/plantpathpapers/541
EC1901
Corn Disease Profile III
Ear Rot Diseases and Grain Molds
UNL Extension Plant Pathology Team
Tamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson,  
Kevin A. Korus, Bo Liu, and Stephen N. Wegulo
2. Diplodia Ear Rot
2a 2b
1. Aspergillus Ear Rot
1
4. Gibberella Ear Rot
4
5. Penicillium Ear Rot
5a 5b
6. Cladosporium Ear Rot
6
7. Moldy Outdoor Storage Pile
7
BB
3. Fusarium Ear Rot
3a 3b
Ear Rot Diseases and Grain Molds
Under certain conditions, corn ear rot and grain mold diseases are common and can lead to loss of grain quality. Moldy grain can be 
docked or rejected at the elevator. Additionally, some ear and grain pathogens may produce secondary metabolites called mycotoxins, 
which are toxic to animals and humans consuming the contaminated grain. Mycotoxin-contaminated grain can also be docked or 
rejected. Mycotoxin production may start in the field and continue after harvest, or it may start during storage if mold infection begins 
there. When grain storage is necessary, drying grain to less than 15 percent moisture for long-term storage or to no more than 18 per-
cent for short-term storage will help reduce fungal growth.
Risk Factors and Stressful Conditions Favoring Ear Rot and Grain Mold Development
• Moisture stress 
• Ear injury
• Extreme weather conditions
• Infected crop residue
• Growing continuous corn
• Susceptible hybrids
• Damaged grain
• High moisture storage conditions
Disease Description
1.  Aspergillus Ear Rot
Aspergillus flavus, A. parasiticus, 
Aspergillus spp.
*Management: C, R, N
Most common during years with high temperatures and drought conditions. 
Aspergillus spores tend to be yellow green to olive green (Figure 1) and infection is 
usually associated with the ear tips or other damaged areas such as those caused by 
insect feeding. These species, especially A. flavus, can produce the mycotoxin aflatoxin. 
2. Diplodia Ear Rot
 Diplodia maydis (syn. Stenocarpella 
maydis)
Management: C, R, N
Thick fungal mycelium evident of Diplodia ear rot most commonly develops at the 
base of the ear first (Figure 2a). Fungal reproductive structures (pycnidia) appear 
as small black dots on kernels (Figure 2b), cob, or husks. Advanced infections may 
overtake ears leading to development of lightweight mummy ears. The pathogen 
overwinters in infected crop residue and disease has been more common in minimum 
tillage and humid environments.
3. Fusarium Ear Rot
Fusarium verticillioides,  
F. proliferatum, F. subglutinans
Management: C, R, N
This disease is common when crop stress occurs around silking. Infection can occur 
anywhere on the ear and can be associated with injury, such as caused by hail (Figure 
3a). It may appear as white to pink cottony fungal growth (Figure 3b). Infected kernels 
may have a “starburst” pattern. Fusarium species may produce mycotoxins, including 
fumonisin, vomitoxin (DON), and/or zearalenone. 
4. Gibberella Ear Rot
Gibberella zeae (sexual stage of  
F. graminearum)
Management: C, R, N
Most common in cool, humid conditions, it is closely related to the pathogen causing 
Fusarium ear rot. Symptoms typically develop as reddish mycelium and discoloration 
on the tips of ears (Figure 4) and may be accompanied by small black fungal 
reproductive structures (perithecia). Mycotoxins may include vomitoxin (DON) and 
zearalenone. 
5. Penicillium Ear Rot
Penicillium spp.
Management: C, N
Often called “blue eye,” Penicillium ear rot develops most often on damaged ears 
and grain. The fungus produces large amounts of dusty blue-green spores (Figure 5). 
Penicillium species also can produce several less common mycotoxins. 
6. Other Grain Molds 
Cladosporium Rot, Nigrospora Ear  
or Cob Rot, Trichoderma Ear Rot
Management: C, N
Appearance and discoloration may vary by disease (Figure 6). Some may be more 
common after damage and premature plant death, such as following early frost, and 
can continue to grow during storage. Outdoor storage piles are especially at risk for 
grain mold development (Figure 7).
Photo Credit: Figures 5a and 6 courtesy of Casey Schleicher and Amy Timmerman, respectively, University of Nebraska–Lincoln, and 
Figure 7 courtesy of Larry Ziems.
*Management strategies which can be effective: C – cultural practices, such as the use of crop rotation, tillage, irrigation timing, or 
grain drying prior to storage may reduce disease; R – resistance: hybrids vary in their resistance/susceptibility and resistance to insects 
can reduce damage and disease severity ; N – management may not be necessary, practical, or possible.
3. Gibberella 
Ear Rot
4. Gibberella 
Ear Rot
4. Charcoal Rot
4b
Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture.
University of Nebraska–Lincoln Extension educational programs abide with the nondiscrimination policies of the University of Nebraska–Lincoln and the United States Department of Agriculture.
© 2012, The Board of Regents of the University of Nebraska on behalf of the University of Nebraska–Lincoln Extension.  All rights reserved.


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Corn Disease Profile III: Ear Rot Diseases and Grain Molds

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