Posted in Crops, Uncategorized

Early Season Flooding

As I write this article, parts of Fillmore County received over 4 inches of rain in less than a 24-hour period, which has brought flooding in some fields. You might wonder how this affects the crop condition so I found an article from Purdue University written May, 2010 that describes what could happen. The longer an area remains ponded, the higher the risk of plant death. The article, Effects of Flooding or Ponding on Young Corn was written by R. L. (Bob) Nielson summarizes the following:

  • Corn that is completely submerged is at higher risk than corn that is partially submerged.
  • Plants that are only partially submerged may continue to photosynthesize, albeit at limited rates.
  • Most agronomists believe that young corn can survive up to about 4 days of outright ponding if temperatures are relatively cool (mid-60’s F or cooler); fewer days if temperatures are warm (mid-70’s F or warmer).
  • Soil oxygen is depleted within about 48 hours of soil saturation. Without oxygen, the plants cannot perform critical life sustaining functions; e.g. nutrient and water uptake is impaired and root growth is inhibited.
  • Even if surface water subsides quickly, the likelihood of dense surface crusts forming as the soil dries increases the risk of emergence failure for recently planted crops.
  • The greater the deposition of mud on plants as the water subsides, the greater the stress on the plants due to reduced photosynthesis.
    • Ironically, such situations would benefit from another rainfall event to wash the mud deposits from the leaves.
  • Corn younger than about V6 (six fully exposed leaf collars) is more susceptible to ponding damage than is corn older than V6.
    • This is partly because young plants are more easily submerged than older taller plants and partly because the corn plant’s growing point remains below ground until about V6. The health of the growing point can be assessed initially by splitting stalks and visually examining the lower portion of the stem (Nielsen, 2008). Within 3 to 5 days after water drains from the ponded area, look for the appearance of fresh leaves from the whorls of the plants.
  • Extended periods of saturated soils AFTER the surface water subsides will take their toll on the overall vigor of the crop.
  • Some root death will occur and new root growth will be stunted until the soil dries to acceptable moisture contents. As a result, plants may be subject to greater injury during a subsequently dry summer due to their restricted root systems.
  • Associated with the direct stress of saturated soils on a corn crop, flooding and ponding can cause significant losses of soil nitrogen due to denitrification and leaching of nitrate N.
  • Significant loss of soil N will cause nitrogen deficiencies and possible additional yield loss.
  • On the other hand, if the corn dies in the ponded areas it probably does not matter how much nitrogen you’ve lost.
  • Lengthy periods of wet soil conditions favor the development of seedling blight diseases, especially those caused by Pythium fungi (Sweets, 2008).
  • Poorly drained areas of fields are most at risk for the development of these diseases and so will also be risky for potential replant operations.
  • Certain diseases, such as common smut and crazy top, may also become greater risks due to flooding and cool temperatures (Malvick, 2002).
  • The fungus that causes crazy top depends on saturated soil conditions to infect corn seedlings.
  • The common smut fungal organism is ubiquitous 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.
Advertisements

One thought on “Early Season Flooding

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s