Wet and warm weather conditions in the fall can cause premature kernel sprouting. Corn products with open husks and upright ears at maturity are more likely to experience kernel sprouting. Fields should be harvested as soon as possible and dried at high temperatures if kernel sprouting is suspected.
Premature germination or sprouting of kernels prior to harvest is also known as vivipary.1 Kernel sprouting can occur when moisture becomes trapped in the husk, allowing kernels to absorb the water and germinate (Figure 1). Kernel sprouting on the cob prior to harvest is most likely to occur when black layer has been reached, kernel moisture has dried to less than 20 percent, and kernels are then exposed to moisture. This more commonly occurs in warmer, southern regions. Corn products that tend to have an upright ear at maturity with an open husk may be more susceptible to kernel sprouting. Continuous rainfall at harvest favors kernel sprouting.
While it is more common after physiological maturity, immature kernels on ears that have been subjected to damage from hail, pests, or ear molds are also known to sprout. It is believed that the physical damage to the immature kernels may disrupt the hormone balance within the kernel and allow for early germination. Factors that can contribute to premature sprouting of kernels include erect corn ears, damage from birds and/or hail, ear molds, wet weather conditions, and stalk breakage and/or lodging.
When premature kernel sprouting occurs, seed quality will be compromised. Sprouted kernels will usually be lighter and affect grain test weight.2 Sprouted kernels are also more susceptible to the development of molds and mycotoxins. These quality issues may result in the grain being discounted when sold.
Some options may help decrease the risk of premature kernel sprouting prior to harvest. Planting a range of corn products with different maturities and growing degree unit (GDU) requirements until flowering is a good practice to help spread out harvest and reduce the likelihood of corn maturing at the same time. If kernel sprouting is suspected, harvest fields as soon as possible. Once harvested, if a high number of kernels are affected, dry grain at higher temperatures to prevent any further growth of the seedlings. Prior to storage, screen grain to remove green growth or damaged kernels.1 Core the stored grain after filling the silo to remove additional sprouted or broken kernels from the center of the bin.
1 Nielsen, R.L. 2012. Premature corn kernel sprouting (aka vivipary). Purdue University Department of Agronomy. http://www.agry.purdue.edu;
2 Thomison,P. and Geyer, A. 2015. Abnormal corn ears. ACE-1-15. Ohio State University Extension. http://u.osu.edu/mastercorn;
3 Weibold, W.J. September 21, 2016. Wet weather can cause seeds to sprout on the plant. Integrated Pest and Crop Management. University of Missouri. https://ipm.missouri.edu.
Web sources verified 07/31/2018.