College News

Vic Martin: Corn Growth and Weather

Great Bend Tribune
Published June 15, 2024

The drought monitor report as of Tuesday, June 11 shows marked improvement in drought conditions. The extreme drought for area is gone after the recent rains and area of severe drought has shrunk and only affects a sliver of northwest Barton County and Pawnee County along with parts of Rush.  Forty-three percent of the state is now out of dry condition up from thirty-six percent last week with the eastern third of the state totally out of dry conditions.  Southwest Kansas is the driest part of the state. The six to ten-day outlook (June 18 to 22) indicates a 50 to 60% chance of likely above normal temperatures and near normal precipitation.  The eight to fourteen-day outlook (June 20 to 26) indicates a 60 to 70% chance of likely above normal for temperatures and near normal precipitation.  Great weather for wheat harvest but not so much for summer crops.

Last week’s column discussed wheat growth and the effects of weather on it.  Today let’s discuss corn. 

  • Again, growth factors include temperature, moisture soil pH, fertility, soil texture and structure, etc. all influence growth and yield.
  • Like wheat, corn forms a root system above the seed with the seed root disappearing over time.  It’s growing point also stays below the surface for an extended period of time, until six leaves are present or around twelve inches.  And like wheat, the growth is above the growing point.
  • Unlike our wheat, corn is a warm season annual grass, planted in the spring and harvested in the fall.  Our wheat is varietal while our field (dent) corn is a hybrid so you can’t keep the seed to plant next spring.  It will germinate and grow but will express a wide range of characteristics.  Corn also has two separate flowers with a female flower, the ear, and a male flower, the tassel.
  • Last week we discussed how wheat needs a period of cold temperatures or it won’t flower, combined with increasing daylength (decreasing night length).  The ancestor of corn, teosinte, comes from the Mexico/Central America area.  A summer annual it’s concerned with producing viable seed before cold temperatures and not trying to avoid winter.  And while daylength changes, it’s not as much as when you move northward.  So unlike wheat, the development of corn we plant is almost exclusively heat driven.  In fact, hybrid maturity is expressed in Growing Degree Units.
  • In simple terms, the seed has to accumulate so much heat to germinate, emerge, produce new leaves, flower, produce seed, and mature.  The total amount varies by hybrid.  While warmer temperatures speed growth and produce larger plants, there are limits.  The formula is to add together the maximum and minimum temperatures, divide by two and subtract 50.  If the minimum is below 50 degrees, you set it at fifty and if the maximum is above 86 degrees, you set it to 86.  Above 86, the plant won’t grow faster and may be stressed, having to shut down.  Below 50, we say there isn’t any positive growth.    This is why during drought/heat stress you will see almost dwarf corn plants the tried to flower and set seed.