Source: P. Thomison, OSU
Symptoms:
Arrested ears exhibit varying degrees of stunting with limited kernel formation. In a moderately arrested ear, the base may appear normal, but have abnormal development between the base and tip of the ear – pollination and kernel development still occur, but at a significantly reduced amount. In severely arrested ears, cob and ovule development cease completely at an early stage of development. Some ear shoots carry either no ear or only the short remnant of an ear. Often silks are absent or limited. Severity of symptoms differs among hybrids. Corn plants with arrested ears generally appear healthy, ie. exhibited normal plant height and color.
Causes:
Applying a nonionic surfactant (NIS) prior to tasseling (VT growth stage) may result in arrested ear development. Some portion of the cob along with ovule development at the tip end of the ear, appears to prematurely cease shortly after a foliar NIS application. The risk appears to be greatest from growth stages V12 to V14 (12 to 14 exposed leaf collars), one or two weeks prior to pollination. Symptoms are evident as early as a week after foliar NIS applications, but are more pronounced three weeks after application.
According to Dr. R.L. Nielsen, given the fact that an affected plant appears otherwise normal indicates that the cause of the arrested ear is not a lingering or cumulative type of stress (e.g., compaction, drought stress, nutrient deficiency), but rather a single stress event that directly affected the developing ear.
Management:
Avoid foliar application of surfactants from the V12 to VT stages.
References:
Below, F. E., K.A. Duncan, M. Uribelarrea, and T. B. Ruyle. Occurence and Proposed Cause of Hollow Husk in Maize Agron. J. 2009 101: 237-242.
Ciampitti, I. 2014. Abnormal Corn Ears. Available at https://www.agronomy.k-state.edu/extension/documents/crop-production/Abnormal_Corn_Ears.pdf [URL verified 3/28/2019]. Kansas State University.
Nafziger, E., 2007. Unexpected problems of corn ear development. Available at http://ipm.illinois.edu/bulletin/article.php?id=836 [URL verified 3/28/2019]. Univ. of Illinois, Urbana.
Nafziger, E., 2008. More ear oddities, and a possible cause. Available at http://ipm.illinois.edu/bulletin/print.php?id=1033 [URL verified 3/28/2019]. Univ. of Illinois, Urbana.
Nielsen, R.L., 2007. Symptomology of arrested ear development in corn. Available at http://www.agry.purdue.edu/ext/corn/news/articles.07/ArrestedEars-0904.html [URL verified 3/28/2019]. Purdue Univ., West Lafayette.
Nielsen, R.L., 2008. Arrested ears resulting from pre-tassel applications of pesticide and spray additive combinations. Available at http://www.agry.purdue.edu/Ext/corn/news/articles.08/arrestedears-1209.html [URL verified 3/28/2019]. Purdue Univ., West Lafayette.
Schmitz, G.L, N.T. Fassler, G.M. Fellows, A.M. Shirley, R.W. Chamblee, C.W. Finch, M.A. Storr, P.M. Vassalotti, T.D. Klingaman, W. E. Thomas, and D. P. Rathmann. Arrested Ear Development in Corn Caused by a Component of Certain Surfactants. Agron. J. 103: 1697-1703