Nebraska Corn: Why Are Corn Kernels Germinating on the Ear?

When corn kernels start sprouting on the ear, it's likely due to an imbalance of plant hormones.

Following last week’s heavy rains, growers in south central Nebraska are reporting sprouting corn kernels in ears in drought-stressed and hail-damaged fields as well as in fields with upright, tight-husked ears not under stress. This kernel germination prior to harvest is called “vivipary.”  

Prior to full maturity it comes down to a hormonal imbalance within the kernels between gibberellin and abscisic acids (ABA). According to a study by White, et. al (2000), gibberellin production with the lack of ABA allowed for kernel germination while less gibberellin and more ABA deterred kernel germination. At full maturity, very little ABA is left in the kernel (in both corn and soybeans) which allows them to germinate in correct conditions after harvest.

These conditions include moisture and temperatures above 50ºF. Thus the continuous drizzle and rain experienced last week can allow for sprouting within soybean pods. In corn, sprouting under those conditions typically occurs at the base of the ear first but we’re also seeing it in exposed ear tips. We’ve also seen Fusarium and Gibberella ear rot fungi occurring in ears that have been damaged by hail and/or insects in ears. These fungi also produce gibberellins which can aid in the hormonal imbalance and stimulate kernel germination.

Figures 2.

 

Photos 2-3. Hail-damaged corn in central Nebraska may be sprouting due to a disruption of normal growth hormones. Photos: Jenny Rees

If you’re seeing kernel sprouting in your field, make sure your crop insurance adjuster is aware of the situation and submit samples for kernel damage due to mold and sprouting. Also check for mycotoxins prior to harvest if ear molds are a problem in your field. The local co-op will decide whether to accept the load based on percent damage and the standards they need to follow. If the load is rejected, contact your crop insurance agent to determine your next step.

Sprouted kernels lead to higher kernel damage and more fines in a load.

4 Keys for harvest will include:

  1. harvesting early,
  2. drying it to 14%, potentially drying at a high temperature to kill the sprout,
  3. screening out fines, and
  4. monitoring stored grain closely for hot spots, mold, and additional sprouting grain.

With the moisture continuing to exacerbate corn ear molds, particularly in hail-damaged fields, you may also decide to take the grain for silage instead.See these CropWatch articles by Nebraska Extension specialists for additional information on making and storing silage:


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