Saturday, April 29, 2017

Evaluating Corn Stands after Excessive Rain

One of the biggest yield robbers (culprit of uneven germination or poor emergence) is due to highly variable soil moisture conditions at planting.  Soil moisture variation can be caused by different soil types, tillage patterns, Mother Nature, or seedling depths.  Too much water at planting can limit oxygen to seed and restrict growth of corn seedling. There is also a risk of poor or uneven germination if soil moisture conditions are too dry at planting or if the planting depth is too shallow.  Be sure to have the appropriate seedling planting depth for optimum corn germination.

  • Oxygen supply can deplete within flooded soils within 48 hours, cooler temperatures help plant survival (reduce speed of respiration), but germinating seed/plant not expected to survive more than 4 days
  • Effects on germinating seeds are not well known, but they need oxygen
  • Smaller seedlings are more susceptible to injury than larger seedlings
  • Some corn hybrids respond better than others
  • If corn is not completely submerged, there is limited diffusion of oxygen from shoot to root (helps increase survival)
  • How quickly water recedes (soil type) will help determine survival
What can you do?
  • If corn is at a later growth stage, evaluate the growing point, if it is dark, the corn will likely die
  • Radicle (root) should be cream colored, if not there may be root disease
  • Surviving plants should start growing 3 to 5 days
  • Flooding/saturation restricts root development, so drought stress could develop later in the season
  • Take stand counts and use the Burrus replant decision chart
For more information, check out Corn and Soybean Survival in Saturated and Flooded Soils.

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