Source: P. Thomison, OSU
Reduced kernel set with varying number of kernels. When severe, ears show mostly cob tissue with just scattered kernels or no distinct kernel rows. If reduction in kernel numbers is limited, ears may exhibit jumbled kernel set.
Poor pollination of ears and incomplete kernel set may be caused by multiple factors including severe drought and high temperatures (due to asynchronous pollen shed and silking, i.e. poor “nick”); inadequate pollen supply due to uneven crop development, herbicides, insect feeding and silk clipping. Phosphorus shortages also interfere with pollination. Avoid late postemergence applications of glyphosate on glyphosate tolerant hybrids and imazethapyr & imazapyr herbicides on imazethapyr & imazapyr tolerant hybrids.
Follow recommended guidelines for minimizing crop stress, including maintaining appropriate soil fertility, adjusting planting depth with varying soil conditions, adhering to recommended herbicide application dates, and selecting adapted hybrids and seeding rates consistent for soil yield potential and date of planting. Avoid planting too early in wet soils. Minimize weed competition with effective herbicide applications and/or timely cultivation. Avoid late postemergent, broadcast herbicide applications.
Abendroth, L.J., R.W. Elmore, M.J. Boyer, and S.K. Marlay. 2011. Corn growth and development. Iowa State Univ. Ext. PMR 1009.
Ciampitti, I. 2014. Abnormal Corn Ears. Available at https://www.agronomy.k-state.edu/extension/documents/crop-production/Abnormal_Corn_Ears.pdf [URL verified 1/16/2019]. Kansas State University.
Nielsen, R.L. 2016. Tassel Emergence and Pollen Shed. Corny News Network, Purdue Univ. Available at http://www.agry.purdue.edu/ext/corn/news/timeless/Tassels.html [URL verified 1/16/2019].
Nielsen, R.L. 2007. Silk Development and Emergence in Corn. Corny News Network, Purdue Univ. Available at http://www.kingcorn.org/news/timeless/Silks.html [URL verified 1/16/2019].
Nielsen, R.L. 2010. Sexual Dysfunction in the Corn Field. Corny News Network, Purdue Univ. Available at http://www.agry.purdue.edu/ext/corn/news/articles.01/Krnl_Set-0820.html [URL verified 1/16/2019].
Nielsen, R.L. 2001. Pollination Failure Due to Herbicide? Available at http://www.kingcorn.org/news/articles.01/Krnl_Set_Herb-0820.html [URL verified 1/16/2019].