Field of Corn (with Osage Orange Trees) Located in Dublin, Ohio, by Malcolm Cochran. Dedicated October 30, 1994.

A corn ear has the potential for 750 to 1000 kernels and may weigh over a pound. However, the corn ears produced in a typical Corn Belt field will average about 450-500 kernels and weigh about 1/4 -1/2 lb. Corn ear size is influenced by cultural practices, especially seeding rates and soil fertility, as well as environmental conditions and soil moisture and temperatures. Corn ears have an even number of kernel rows that can range from 12 to 22 rows (usually about 14-18 rows).  Row number is primarily determined by genetics whereas kernel number per row (ear length) is strongly influenced by growing conditions.

 

 

Normal Ear of Corn with About 37 Kernels per Row

Cross Section of Normal Corn Ear (butt end) Exhibiting 18 Kernel Rows

 

 

 

 

 

 

The appearance of a corn ear during grain fill or at harvest 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, – about the 5-6 leaf collar stage (V5-6), when the ear sets the maximum number of kernels along length of the ear – about the 15 leaf collar stage (V15), when the maximum number of ovules are pollinated to form developing embryos – the blister stage (R2), when the maximum number of kernels is determined – the milk stage (R3), and when the maximum kernel size is established – late dough/early dent stage (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 problem involved. An ear abnormality may be associated with more than one cause and ears may 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, condition 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 corn producing regions of the U.S. and the world and strategies for managing them.

 

3-D images are available for select abnormalities.  These are indicated by (3-D) following the abnormality name below.  3-D images can also be found here:  http://u.osu.edu/mastercorn/3-d-images/

 

 

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

Arrested Ears

Source: P. Thomison, OSU

 

 

Bar Bell Ears

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

 

Bear Claw Deformities

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

 

 

Blunt Ears

Source: P. Thomison, OSU

 

 

Bouquet Ears

Source: P. Thomison, OSU

 

 

Chaffy Ears

Source: P. Thomison, OSU

 

 

Cow Horn, Boomerang and Banana Ears (3-D)

Source: Dennis Belcher, BASF, 2007.

 

 

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.

 

 

Ear Pinching (3-D)

Source: P. Thomison, OSU

 

 

Ears with Extended Leaf Husks

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

 

 

Exposed Ear Tips

Source: P. Thomison, OSU

 

 

Hail Damage

Ear damaged by hail at early to mid grainfill.
Source: P. Thomison, OSU

 

 

Incomplete Basal Fill

Source: P. Thomison, OSU

 

Incomplete Kernel Set – Whole Ear

Source: P. Thomison, OSU

 

 

Kernel Jumbling

Source: P. Thomison, OSU

 

 

Long Ear Shanks

Long Ear Shank. Source: B. McDonald, 2019.

 

 

Nubbin Ears

Source: P. Thomison, OSU

 

 

Poor Tip Fill

Source: OSU Extension

 

 

Purpling of Ear Husks

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

 

 

Silkballing

Source: Dewey Lee, Univ. of Georgia

Source: Dewey Lee, Univ. of Georgia

 

 

Tassel Ears

Source P.Thomison, OSU

 

 

Tip Dieback

Source: P. Thomison, OSU

 

 

Zipper Ears (3-D)

Source: P. Thomison, OSU

 

ABNORMAL KERNEL DEVELOPMENT

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

 

 

Popped Kernels

Source: 2009 Brian Frischmeyer Iowa

 

 

Premature Sprouting (3-D)

Source: P.Thomison, OSU

 

 

Silk Cut

Source: Purdue University

 

 

Translucent Kernels

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

 

EAR MOLDS AND DISEASE

Aspergillus Ear and Kernel Rot

Source: Gary Munkvold, Iowa State University Plant Pathology

 

 

Blue Eye Mold

Source: USDA FGIS/Education and Outreach Visual Reference Library

 

 

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)

 

 

Corn Smut (3-D)

Common Corn Smut in ears at R5.
Source: P. Thomison, OSU

 

Diplodia Ear Rot

Source: P. Thomison, OSU

 

Fusarium Ear and Kernel Rot (3-D)

Source: P. Lipps, OSU Plant Pathology

 

 

Gibberella Ear Rot

Source: P. Lipps, OSU Plant Pathology

 

 

Nigrospora Ear Rot

Source: Gary Munkvold, Iowa State University

 

 

Trichoderma Ear Rot

 

FEEDING INJURY

Bird Damage

Source: P. Thomison, OSU

 

Corn Earworm

Source: University of Missouri

 

 

European Corn Borer

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

 

 

Fall Army Worm

Source: USDA

 

 

Kernel Red Streak (3-D)

Source: P. Thomison, OSU

 

 

Stink Bug Injury (3-D)

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

 

 

Western Bean Cutworm

Source: OSU Extension Entomology

 

Field of Corn (with Osage Orange Trees) Located in Dublin, Ohio. Each ear of corn is made from white architectural precast concrete and weighs 1500 lbs. A total of 109 ears are present.