OHIO STATE UNIVERSITY EXTENSION Abnormal Corn Ears ACE-1-15 Authors: Peter Thomison* ACKNOWLEDGMENTS: Picture of Diplodia ear rot in corn ear with (Courtesy S.C. Dalmacio) reprinted with permission from American Phytopathological Society. Western and Allen Geyer We thank Pierce Paul and Dennis Mills, OSU Plant Pathology, for their contributions of ear rot pictures. Design by John Victor, CFAES Communications. *614-292-2373 ([email protected]) Copyright © 2015, The Ohio State University Bean Cutworm Ear Injury Symptoms: Scattered patches of partial and/or complete kernel Ear Pinching destruction. Injury often associated with mold growth on affected Beer Bottle Ears kernels. Symptoms: Kernel row number Causes: Kernel feeding by may decrease by half from bottom western bean cutworm. Tends to to top of ear (for example—from 16 be restricted to limited parts of the to 7 to 8 kernel rows/ear). Ear length ear. Western bean cutworm often is usually normal. enters ear through the husk in the sides of the ear. Partially consumed Causes: Severe stress during kernels may be further attacked the 7 to 10 collar stages may by ear molds or secondary insect result in reduced numbers of kernel feeders that enter the ear through rows. Late broadcast application of the cutworm’s feeding channel. sulfonylurea herbicides can result in ear pinching. Bird Damage Symptoms: Lightweight, Blunt Ear weathered ears with damaged, discolored moldy kernels that have Syndrome been subjected to bird and insect feeding; often associated with Beer Can Ears kernel sprouting. Ear Stunting Causes: Poor husk coverage at Symptoms: Characterized by maturity combined with upright ears with markedly reduced ear size ear orientation allows bird feeding and kernel numbers per row. Husk of tip kernels that may lead to length and kernel row number may secondary insect feeders. Moisture be normal. Sometimes associated accumulation at base of ear with multiple ears at a node. promotes molds and may result in Occurrence is usually rare and Tassel Ears germination of scattered kernels. sporadic within a field. During late Multiple Ear Diplodia Symptoms: Combination tassel Tip Dieback fill and redden and ear in the same structure—a Symptoms: Poor tip fill or and purple. Ear Rot Syndrome “tassel ear.” The ear portion of Poor unfilled ear tips; little or no kernel Symptoms: Part or the Kernel Red Cause: Unknown. Associated this tassel ear structure usually development on the last one or Bouquet Ears entire ear is rotted by a white mold Zipper Ears Chaffy Ears with temperature stress (brief contains only a limited number of Pollination more inches of the ear tip. Kernel growing between the kernels. cold shock?) during early ear Characterized by kernels. Tassel ears often appear abortion at tip end of ear at the Symptoms: Lightweight ears Streak Symptoms: Infections generally start at base of Banana Ears formation stages (V8-12). Differs ears with markedly reduced ear size Drought on tillers (suckers) arising from at Ear Tip blister and milk stages; usually with poorly filled, shrunken kernels. Symptoms: Red streaks form on ear and progress to the tip. Later the in severity among hybrids. and kernel numbers per row. Husk plants with normal ears and tassels. associated with poor ovule Symptoms: Missing entire or Spaces between kernels indicating sides of kernels and extend over the white mold changes to a grayish- Symptoms: Cob tissue without length and kernel row number may Damaged These tassel ears are produced at a fertilization at tip. Ovules not parts of kernel rows on the outside incomplete kernel fill. crown. Usually limited to kernels at brown growth over the husks and kernels on the last one or more be normal. Sometimes associated terminal position on the tiller where fertilized and aborted kernels may or underside of the ear primarily tips of ear. kernels. The entire ear may be inches of the ear tip. Ovules not Multiple causes: Severe stress with multiple ears at a node. Ears a tassel would normally appear. both appear dried up and shrunken, due to kernel abortion. Ears often shrunken, and the infected kernels fertilized at ear tip. (photosynthetic stress) at dough Causes: Caused by toxin Occurrence is usually rare and but aborted kernels often have a misshapen and bend (like banana) Causes: Tassel ears often appear glued to the husks. Hybrids (R4) through early dent (R5) stages, secreted during feeding by the sporadic within a field. During late Nubbin Ears Causes: Poor fertilization of ear slight yellowish color. due to differential kernel formation produced by tillers (suckers) vary in susceptibility. including frost damage, premature curl mite. Severity of grain fill husks and leaves redden tip ovules at silking. Same as those along ear. Symptoms: Small misshapened when growing point is destroyed Causes: Stress conditions plant death due to drought, high symptom expression varies among and purple. Diplodia ear rot is caused for Poor, Incomplete Kernel Set. ears with poor kernel set, especially or injured by hail, frost, flooding, Cause: during early kernel development, Causes: Unknown. Often plant population, foliar diseases, hybrids. by the fungus Stenocarpella maydis. severe potassium deficiency and Cause: Unknown. Associated at ear tip. Reduced kernel numbers herbicides and mechanical injury. including severe drought and high associated with severe drought Infection may occur from late hail. with temperature stress (brief cold associated with reduced kernel row Some hybrids may also be more temperatures; nitrogen deficiencies, stress or defoliation injury following vegetative stages to 3 weeks after shock?) during early ear formation and kernels per row. prone to tiller under certain foliar diseases, cloudy weather. pollination. midsilk. Poor, stages (V8-12). Differs in severity environmental conditions and Cause: Severe drought from mid among hybrids. these tillers may give rise to tassel vegetative growth through early ears. Tassel ears are frequently Incomplete to mid grain fill. Other stresses, observed along the edges of fields including nitrogen deficiency and where early season soil compaction Kernel Set high plant population, can result in and saturated soil conditions may Poor, reduced nubbin ears. Symptoms: have contributed to this abnormal kernel set; only a limited number of development. kernels (ovules) pollinated. When severe, ears show mostly cob tissue with just scattered kernels or no distinct kernel rows. Multiple causes: Poor pollination of ear due to asynchronous pollen shed and 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.

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