ACE-1

ACKNOWLEDGEMENTS: Picture of Diplodia ear rot in corn ear with (Courtesy S.C. Dalmacio) reprinted with permission from American Phytopathological Society. We thank Pierce Paul and Dennis Mills, OSU Plant Pathology, for their contributions of ear rot pictures. Design by John Victor, Communications and Technology. Copyright © 2007, The Ohio State University Western Bean Cutworm Ear Injury

Symptoms: Scattered patches of partial and/or complete kernel destruction. Injury often associated with mold growth on affected kernels

Causes: Kernel feeding by Ear Pinching western bean cutworm. Tends to be restricted to a limited Beer Bottle Ears parts of the ear. Western bean cutworm often enters ear through Symptoms: Kernel row the husk in the sides of the ear. number may decrease by half Partially consumed kernels may from bottom to top of ear (for be further attacked by ear molds example - from 16 to 7 to 8 kernel or secondary insect feeders rows/ear). Ear length is usually that enter the ear through the normal. cutworm’s feeding channel. Causes: Severe stress during the 7 to 10 collar stages Bird may result in reduced numbers of kernel rows. Late broadcast Damage application of sulfonylurea herbicides can result in ear Symptoms: Lightweight, pinching. weathered ears with damaged, discolored moldy kernels that have been subjected to bird and Blunt Ear insect feeding; often associated Syndrome with kernel sprouting. Beer Can Ears Causes: Poor husk coverage at maturity combined with upright Ear Stunting ear orientation allows bird feeding of tip kernels that may Symptoms: Characterized Diplodia Poor lead to secondary insect feeders. by ears with markedly reduced Tassel Ears Moisture accumulation at base ear size and kernel numbers Pollination of ear promotes molds and may Symptoms: Combination Ear Rot per row. Husk length and result in germination of scattered tassel and ear in the same kernel row number may be Symptoms: Part or the at Ear Tip kernels. normal. Sometimes associated structure - a “tassel ear.” The ear portion of this tassel ear structure entire ear is rotted by a white Tip Dieback with multiple ears at a node. Symptoms: Cob tissue without usually contains only a limited mold growing between the Zipper Ears Occurrence is usually rare and kernels on the last one or more number of kernels. Tassel ears kernels. Infections generally start Symptoms: Poor tip fill Kernel Red sporadic within a field. inches of the ear tip. Ovules not Banana Ears Multiple Ear often appear on tillers (suckers) at base of ear and progress to the or unfilled ear tips; little or no tip. Later the white mold changes fertilized at ear tip. kernel development on the last Streak Cause: Unknown? Associated arising from plants with normal Symptoms: to a grayish-brown growth over one or more inches of the ear Missing entire with temperature stress (brief Syndrome ears and tassels. These tassel the and kernels. The entire Causes: Poor fertilization of ear tip. Kernel abortion at tip end of or parts of kernel rows on the Chaffy Ears Symptoms: Red streaks form cold shock?) during early ear Drought ears are produced at a terminal Bouquet ears ear may be shrunken, and the tip ovules at silking. Same as those ear at the blister and milk stages; outside or underside of the ear on sides of kernels and extend formation stages (V8-12) and position on the tiller where a infected kernels appear glued for Poor, Incomplete Kernel Set. usually associated with poor primarily due to kernel abortion. Symptoms: Lightweight over the crown. Usually limited to more recently with pretassel Symptoms: Damaged tassel would normally appear. Characterized to the husks. Hybrids vary in ovule fertilization at tip. Ovules Ears often misshapen and bend ears with poorly filled, shrunken kernels at tips of ear. applications of certain foliar by multiple ears on the same ear Causes: susceptibility. not fertilized and aborted kernels (like banana) due to differential kernels. Spaces between kernels chemicals. Differs in severity Ears Tassel ears often shank. In some cases as many as Poor, may both appear dried up and kernel formation along ear. indicating incomplete kernel fill. Causes: Caused by toxin among hybrids. 5 or 6 “side” ears may develop produced by tillers (suckers) Cause: Nubbin Ears when growing point is destroyed Diplodia ear rot shrunken, but aborted kernels secreted during feeding by forming a “bouquet”. Side ears Causes: Unknown. Often or injured by hail, frost, flooding, is caused by the fungus Incomplete often have a slight yellowish color. Multiple causes: Severe the curl mite. Severity may be well developed or may Symptoms: associated with severe drought Small herbicides, and mechanical injury. Stenocarpella maydis. Infection stress (photosynthetic stress) of symptom expression varies resemble “beer can” ears or mere stress or defoliation injury misshapened ears with poor Some hybrids may also be more may occur from late vegetative Kernel Set Causes: Stress conditions at dough (R4) through early among hybrids. remnant ears. Many probably fail following pollination. kernel set, especially at ear prone to tiller under certain stages to 3 weeks after midsilk. during early kernel developmnt, dent (R5) stages, including to form kernels due to late silk tip. Reduced kernel numbers Symptoms: Poor, reduced including severe drought and frost damage, premature plant emergence and lack of pollen. environmental conditions and associated with reduced kernel these tillers may give rise to tassel kernel set; only a limited number high temperatures; nitrogen death due to drought, high plant row and kernels per row. ears. Tassel ears are frequently of kernels (ovules) pollinated. deficiencies, foliar diseases, population, foliar diseases, severe Cause: Unknown. Similar to observed along the edges of When severe, ears show mostly cob cloudy weather. potassium deficiency and hail. those noted under “Blunt Ear Cause: Severe drought from fields where early season soil tissue with just scattered kernels or Syndrome”. mid vegetative growth through compaction and saturated soil no distinct kernel rows early to mid fill. Other conditions may have contributed stresses, including nitrogen to this abnormal development. Multiple causes: Poor deficiency and high plant pollination of ear due to population, can result in nubbin asynchronous pollen shed and ears. silking (poor “nick”) due to severe drought and high temperatures; inadequate pollen supply due to uneven crop development, herbicides, insect feeding and silk clipping. Phosphorus shortages also interfere with pollination.

More information on abnormal corn ears is available online at http://agcrops.osu.edu/corn/EARABNORMALITIES.php