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Figure 1. Drought-damaged “nubbin65533;? ears. Source: The Ohio State University.
Drought stressed corn can manifest itself at harvest in several different forms. Appearance of ear abnormalities caused by drought stress may be present in some or all of your fields. Different environmental conditions and their interaction with various corn products at different times during the season can cause highly varied corn ears. The following is a look at some of the possibilities you may encounter.
Figure 2. Poor, incomplete kernel set. Source: The Ohio State University.
Drought Damaged or “Nubbin65533;? Ears appear small and misshapen with poor kernel set, especially towards the tip. Expect fewer kernels per ear due to reduced number of rows and kernels per row. Typically caused by severe drought from mid-vegetative growth through early to mid-grain fill, nubbin ears may also be caused by nitrogen deficiency and high plant populations.
Figure 3. Tip dieback. Source: The Ohio State University.
Poor, Incomplete Kernel Set produces ears that had only a limited number of kernels pollinated. When severe, you may see primarily cob tissue with only scattered kernels. Poor kernel set can be caused by poor pollination of the ear due to drought and high temperatures creating a lag between pollen shed and silking or inadequate pollen supply, which can be due to several factors.
Figure 4. “Zipper65533;? or “Banana65533;? ears. Source: The Ohio State University.
Tip Dieback results in ears with poor tip fill or little to no kernel development on the last few inches of the ear tip. Tip dieback is caused by stress during kernel development due to severe drought and heat, nitrogen deficiencies, foliar diseases, or cloudy weather.
“Zipper65533;? or “Banana65533;? Ears are missing entire or parts of kernel rows on the outside or underside of the ear due to kernel abortion. The differential ear formation along the length creates a zipper appearance and can cause the ear to bend like a banana. The cause is unknown, but it is often associated with severe drought stress.
Chaffy Ears are lightweight ears with poorly filled, shrunken kernels and spaces between kernels. There are multiple causes, but these may be seen in areas that experienced premature plant death due to drought.
Thomison, P, and Geyer, A. 2007. Abnormal Corn Ears ACE-1. The Ohio State University. 161027080530