The Importance of Monitoring Freshly Planted Corn When the Weather Turns Cold and Wet

There is nothing better than planting corn knowing that the weather conditions are perfect. And, as any farmer can tell you, there is nothing worse than when the weather takes a turn for the worse shortly after planting.

Imbibitional chilling is a huge concern for corn seeds that have been planted or are in the early stages of germinating. In such cases it is critical to give these seeds extra attention when you scout early planted corn for germination and emergence.

Imbibition occurs when seeds absorb water for the process of germinating. Imbibition of cold water can cause issues since cold water upsets the reorganization of cells during rehydration. The result is a loss of seed vigor, or worse, seed death. The impact of imbibitional chilling is worse when the soil that seeds are planted in is 50 degrees or lower than it is when seeds are planted in warm soil followed by a drop in temperatures.

Corn seed absorbs about a third of its weight in water during the early process of germination. If this water is too cold, trouble can start. Temperatures in the upper 40s to low 50s are considered the danger zone by most agronomists. One of the most troubling occurrences is that the cell walls of the germinating corn seedling becomes brittle and ruptures. Other problems may occur, as well, including:

  • The rupture of coleoptiles
  • Corkscrewed corn seedlings
  • Corn that leafs out underground
  • Seedlings that are more prone to pathogens
  • The death of seedlings
  • Seeds that swell but don’t grow

When corn is planted a day or two before a cold front that includes rain, seeds can imbibe the cold water. However, it isn’t the cold water itself that is the issue when it comes to imbibition. Instead it is the growth of the radicle root which is directly linked to soil temperature. For example, the radicle root of a germinating corn seedling will grow when the soil is as low as 46 degrees but the mesocotyl and coleoptile need temperatures to be about 15 degrees higher than that in order to grow. Without these higher temps, emergence can be negatively impacted, or plants may experience stunted growth. Therefore, if fields are planted ahead of cold weather, it is critical to monitor those fields to determine whether they are growing normally.

It is important to keep in mind that cold soil or imbibitional chilling issues often only impact a small area of soil or particular corn hybrids. If the damage is more widespread, replanting may be necessary.

Thankfully, most of today’s corn hybrids are durable and improved genetics allow them to withstand a great deal of stress. Advanced fungicide and insecticide seed treatments also increase the chances of a healthy stand of corn.