Long periods of saturated soils after surface water subsides also can take their toll on a corn crop. This saturation can cause root death, or stunt new root growth until soil moisture returns to a more normal level. Nielsen said corn plants can then be more susceptible to stress and injury during a dry summer because they have restricted root systems.
Along with direct stresses of saturated soils, flooding and ponding can cause significant soil nitrogen loss due to denitrification and leaching.
"Significant loss of soil nitrogen will cause nitrogen deficiencies and possible additional yield loss," Nielsen says. "On the other hand, if corn dies in the ponded areas, it probably doesn't matter how much nitrogen has been lost."
Finally, long periods of wet soil conditions favor development of seedling blight diseases, especially those caused by Pythium fungi, he says. Poorly drained areas of the field are at the highest risk.
Common smut and crazy top also can become greater risks from flooding and cool temperatures.
"The fungus that causes crazy top depends on saturated soil conditions to infect corn seedlings," Nielsen says. "The common smut fungal organism is present in soils and can infect young corn plants through tissue damaged by floodwaters. There is limited hybrid resistance to either of these two diseases and predicting damage is difficult until later in the growing season."
More information about the 2011 corn crop is available on Purdue Extension's Corny News Network at: http://www.agry.purdue.edu/ext/corn/cafe/
Source: Purdue University