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.
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: https://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
Ear Pinching (3-D)
Zipper Ears (3-D)
ABNORMAL KERNEL DEVELOPMENT
Premature Sprouting (3-D)
EAR MOLDS AND DISEASE
Corn Smut (3-D)
Kernel Red Streak (3-D)
Stink Bug Injury (3-D)