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The appearance of a corn ear can tell us much about a corn plant’s development during the growing season. Ear size and numbers and distribution of kernels on the ear can indicate when the ear experienced stress and the severity of the stress. Ear size and kernel number are determined at five critical stages: when the ear sets the maximum number of kernels, – V5-6, when the ear sets the maximum number of kernels along length of the ear – V15, when the maximum number of ovules are pollinated to form developing embryos – R2, when the maximum number of kernels is determined – R4, and when the maximum kernel size is established – R5. Abnormal ear development has multiple causes – environmental stresses, pests, cultural practices. Combined with information on field history, knowledge of ear and kernel anomalies can be an effective diagnostic tool in troubleshooting corn production problems. A corn ear’s response to a particular stress may be so unique that it can specify the stress condition involved. An ear abnormality may also be associated with more than one cause. Moreover, ears may often exhibit injury symptoms in response to more than one stress. Understanding how corn ears respond to stress can help determine the nature of the stress, when it occurred, and how it might be managed or avoided in the future. This web page describes over 40 types of abnormal ear and kernel development that occur in Ohio and other U.S. corn producing regions of and strategies for managing them.

 

CORN ABNORMALITIES by CATEGORY:

EAR, KERNEL, DISEASE, MOLDS, FEEDING

 

To learn more, click the name of the problem you want to diagnose and manage.

 

     ABNORMAL EAR DEVELOPMENT

Silkballing

Source: Dewey Lee, Univ. of Georgia

Source: Dewey Lee, Univ. of Georgia

Source: Dewey Lee, Univ. of Georgia

Source: Dewey Lee, Univ. of Georgia

Ear Pinching

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Blunt Ears

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Bouquet Ears

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Bar Bell Ears

Source: Dr. Pat Lipps, Ohio State University Extension Plant Pathology

Source: Dr. Pat Lipps, Ohio State University Extension Plant Pathology


Bear Claw Deformities

Source: Hubert Brochard, Quebec Bear Paw Ear (Sweet corn)

Source: Hubert Brochard, Quebec
Bear Paw Ear (Sweet corn)

Nubbin Ears

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Tassel Ears

Source P.Thomison, OSU

Source P.Thomison, OSU

Cow Horn, Boomerang and Banana Ears

Source: Dennis Belcher, BASF, 2007.

Source: Dennis Belcher, BASF, 2007.

Arrested Ears

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Crazy Top

Source - R. Lewandowski, OSU Extension, Athens Co., OH, 2008 Crazy top associated the with ear shoot is common. This ear sample was from a sweet corn field.

Source – R. Lewandowski, OSU Extension, Athens Co., OH, 2008
Crazy top is not usually associated with ear shoots.  This ear sample was from a sweet corn field.

Purpling of Ear Husks

Purpling of husk - sweet corn. Source: S. Kerr, Washington State University Klickitat County Extension

Purpling of husk – sweet corn. Source: S. Kerr, Washington State University Klickitat County Extension

Ears with Extended Leaf Husks

Leaf like husks Source: Mark Mechling, OSU Extension Muskingum County

Leaf like husks
Source: Mark Mechling, OSU Extension Muskingum County

Exposed Ear Tips

Source: P. Thomison, OSU

 

EAR ANOMALIES – ABNORMAL KERNEL DEVELOPMENT

Incomplete Kernel Set – Whole Ear

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Poor Tip Fill

Source:

Source: OSU Extension

Incomplete Basal Fill

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Tip Dieback

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Zipper Ears

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Chaffy Ears

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Translucent Kernels

Source: Mike Vose, University of Illinois Orr Research Center.

Source: Mike Vose, University of Illinois Orr Research Center.

Mixed Kernel Colors

Ears of yellow dent corn ears (two on left) and blue color (two on right) two center ears from adjacent rows. Two outside ears from plants approx 40 row rows away from blue or yellow kernel plants. Source: P. Thomison, OSU

Ears of yellow dent corn ears (two on left) and blue color (two on right) two center ears from adjacent rows. Two outside ears from plants approx 40 row rows away from blue or yellow kernel plants.
Source: P. Thomison, OSU

Popped Kernels

Source: 2009 Brian Frischmeyer Iowa

Source: 2009 Brian Frischmeyer Iowa

Silk Cut

Source: Purdue University

Source: Purdue University

Hail Damage

Source: P.Thomison, OSU

Source: P.Thomison, OSU

Premature Sprouting

Source: P.Thomison, OSU

Source: P.Thomison, OSU

EAR MOLDS AND DISEASE

Diplodia Ear Rot

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Gibberella Ear Rot

Source: P. Lipps, OSU Plant Pathology

Source: P. Lipps, OSU Plant Pathology

Fusarium Ear and Kernel Rot

Source: P. Lipps, OSU Plant Pathology

Source: P. Lipps, OSU Plant Pathology

Blue Eye Mold

Source: USDA FGIS/Education and Outreach Visual Reference Library

Source: USDA FGIS/Education and Outreach Visual Reference Library

Aspergillus Ear and Kernel Rot

Source: Gary Munkvold, Iowa State University Plant Pathology

Source: Gary Munkvold, Iowa State University Plant Pathology

Nigrospora Ear Rot

Source: Gary Munkvold, Iowa State University

Source: Gary Munkvold, Iowa State University

Cladosporium Ear Rot

Source: A. Robertson, Iowa State University Plant Pathology. Cladosporium ear rot may develop as dark (brown to green) fuzzy mold growing on and between kernels (http://www.extension.iastate.edu/CropNews/2009/1030robertsonmunkvold.htm)

Source: A. Robertson, Iowa State University Plant Pathology.
Cladosporium ear rot may develop as dark (brown to green) fuzzy mold growing on and between kernels (http://www.extension.iastate.edu/CropNews/2009/1030robertsonmunkvold.htm)

Corn Smut

Source: P. Lipps, OSU Plant Pathology

Source: P. Lipps, OSU Plant Pathology

Trichoderma Ear Rot

FEEDING INJURY

Western Bean Cutworm

Source: OSU Extension Entomology

Source: OSU Extension Entomology

Corn Earworm

Source: University of Missouri

Source: University of Missouri

European Corn Borer

Source: H. Willson and B. Eisley, OSU- Extension Entomology.

Source: H. Willson and B. Eisley, OSU- Extension Entomology.

Fall Army Worm

Source: USDA

Source: USDA

Bird Damage

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Kernel Red Streak

Source: P. Thomison, OSU

Source: P. Thomison, OSU

Stink Bug Injury

Late season BMSB kernel injury in corn at dough stage. Waterman Farm, Columbus OH 2014. Source: P. Thomison, OSU Horticulture and Crop Science

Late season Brown Marmorated Stink Bug kernel injury in corn at dough stage. Waterman Farm, Columbus OH 2014. Source: P. Thomison, OSU Horticulture and Crop Science