Early planted corn growth has slowed with cool soil temperatures. Corn takes about 100 to 120 growing degree days to emerge. With average air temperatures of 45° F., research has shown in may take three to four weeks to emerge. Monitoring soil temperatures will provide insight into how fast corn will emerge.

Soil temperatures are measured at the University of Missouri weather stations located at the Buchanan County Extension office in St. Joseph and the Hundley-Whaley Research Center in Albany and track weather in real time. Graves-Chapple Research Center weather is uploaded and then reported daily.

Cold soil temperatures can cause other corn emergence problems. Cold soil temperatures after planting within the first 24 to 48 hours can cause what is known as “inbibitional chilling.” Corn seed is typically at 8 percent moisture and when seed is placed into the soil, it hydrates. If soils are cold, the cells are not as elastic and may break. This does not happen very often but when it does, it results in extremely poor corn stands.

Low soil temperatures can cause other corn emergence problems. Heavy, wet snow in northwest Missouri may result in a compacted soil surface which may restrict corn emergence. The coleoptile can rupture as it tries to push through dense soil surface and causing the leaves to unfurl under the soil surface. In addition, as soil temperatures swing up and down, this can result in the same type of injury. Corn may have corkscrewed mesocotyl.

The severity of any kind of corn emergence damage will require time. Scout fields a week to 10 days after the injury event to determine if there is any injury to your fields. If soil temperatures warm, you may be able to assess fields earlier.

For more information, contact Wayne Flanary, Field Specialist in Agronomy, University of Missouri Extension at 816-279-1691.