Looking at Multiple Ears on Corn Plants

The Dairyland Agronomy Team has had a few questions about corn plants producing more than one ear. We’ll look at the two ways this can show up in the field.

Multiple Ears on One Stalk

Although our modern hybrids generally produce one main ear per plant, it is not unusual to find two. Plants produce many ear-shoots up and down the stalk during vegetative growth stages, partially to hedge against environmental adversity. Pollination of the primary ear establishes apical dominance, thus aborting subsequent ears. There are many theories for the cause of multiple ears making it to harvest. The most common is the “extra resource” idea. The logic is that favorable growing conditions, extra fertility, or maybe lower population allows each plant to proliferate. Multiple ears in a stressed scenario might suggest an opposite theory; that the plant was so focused on playing defense that it didn’t, or couldn’t, signal ear abortion when and where it should. Delayed pollination of the primary ear could be a major factor.

The additional ear(s) usually develop on separate nodes below the primary ear and are almost always smaller than the primary ear (see Figure 1). If the primary ear is still developing normally there is little to worry about. In some cases, the multiple ears contribute viable grain, other times the plant will continue to prioritize the primary ear.

Multiple Ears on One Node

A more uncommon sight is the development of multiple ears on the same node (see Figure 2). This phenomenon is referred to as multiple ears per node, bouquet ears and MESS Syndrome (Multiple Ears on Same Shank). These ears usually experience stunting, abnormal growth and pollination issues which can negatively impact yield. The yield impact can vary greatly depending on if one ear is more dominant than the rest, how many ears are formed at the same node, and how many plants are affected.

Although the cause is unknown, researchers have identified some common links with this phenomenon. One common factor is when the primary ear was damaged, failed to develop or didn’t pollinate correctly which results in the loss of apical dominance. The plant uses hormonal apical dominance to suppress more than one ear from forming on a node. Another link is when the plant endures stress during early ear formation (around V5-V7 timing) which can cause developmental issues with the ear and eventually loss in apical dominance. Some of the early stressors to watch out for include wide temperature fluctuations including exposure to cool temperatures, high winds, flooding or drought stress. There is not an obvious link between applications and/or application timing of herbicides, insecticides or fungicides and the development of multiple ears on a node. There is also no conclusive link to specific hybrids or germplasm. If you have any questions, please reach out to your local Dairyland Seed DSM or Agronomist.