In recent weeks, I have received several reports of abnormal ear development in corn fields which are near or at harvest maturity. Affected plants in these fields exhibit varying degrees of ear development with little or no kernel formation. Some ear shoots carry a barely visible rudimentary ear or only the short remnant of an ear (Figs. 1 and 2).
Other symptoms include “dumbbell-shaped ears” (characterized by kernel formation at the base and tip of the ear but absent from the middle of the ear), “bouquet ears” (formed by small ears trying to develop from the same shank as the main ear), and shorter than normal husks. The ear development problems are evident throughout fields with nearly all plants affected. Prior to maturity, corn plants exhibiting abnormal ears generally appeared healthy with normal plant height and color. However, at harvest, plants with abnormal ear symptoms usually turned purple due to an accumulation of anthocyanin pigments in the leaf and stalk tissue. The visual symptoms resemble those of ear development problems observed in the past - “Arrested Ears” (http://u.osu.edu/mastercorn/arrested-ears/) and “Blunt Ear Syndrome” (http://u.osu.edu/mastercorn/blunt-ears/). Several of the symptoms we have observed this year are similar to those associated with ear formation issues reported by agronomists at the University of Nebraska in 2016 – dumbbell shaped ears, multiple ears per node and short husks (https://cropwatch.unl.edu/2016/corn-ear-formation-issues-likely-correlated-loss-primary-ear-node).
For more on ear development problems and others ear abnormalities, check the following: “Troubleshooting Abnormal Corn Ears” available online at http://u.osu.edu/mastercorn/
Fig. 1. Ear shoot carrying only the remnant of an ear. Symptoms suggest ear development arrested as early as V12.
Fig. 2. Ear exhibiting no kernel formation (husks removed for photo). Symptoms suggest
ear development arrested 1-2 weeks before tasseling.