Rest in Pieces: Hail Can Cause Major Damage for Corn

July 6, 2009 07:00 PM

Rachel Duff, Farm Journal Intern
By destroying leaves and reducing stands, hail can wreak havoc on a corn crop, especially this late in the season, says Roger Elmore, professor of agronomy at Iowa State University.
For corn, the growing point (the area of the corn plant where leaves and the tassel are initiated, located at the base of the stalk) is a visual indicator of the plant's health. If the growing point is above ground and damaged by hail, the corn cannot recover, he says.
A healthy growing point is a white to cream color. Whereas, a brown growing point is a sign of death, he says. The brown growing point indicates the corn has rotted. This can be seen by cutting the plant lengthwise.
If your field has been hailed, Elmore provides this some advice:
  • Wait it out for a couple days. It takes four to five days of good weather for corn to recover. Call your crop insurance agent, hail adjusters are trained and equipped to assess hail damage losses. Wait at least three to five days after a hail storm to obtain an accurate damage appraisal.  
  • Evaluate crop growth stage. Corn growth stage at the time of the storm is critical. If the plant has less than six collared leaves, yield will rarely be affected. Expect re-growth. This is true regardless of the amount of defoliation if weather after the storm favors growth. Much of the corn at this time of the year has vulnerable growing points.
  • Assess viable stands. Evaluate injured plants to determine the growing point's viability. Use a sharp knife and cut lengthwise down the stem. Plants with a healthy growing point should survive. Make assessments of plant survival three to five days after the storm allowing plants to recover. If weather is not conducive for plant growth for a prolonged period after the storm, assessing the remaining stand may require waiting up to a week.
  • Estimate yield losses from defoliation. As mentioned, leaf loss or defoliation will rarely affect yield before the sixth leaf stage. Plants with six leaves or greater will experience yield losses depending on the extent of the defoliation.
  • Estimate yield losses from stand reductions. Stand loss may occur following significant hail storms. Small reductions in plant survival do not impact yields much; for example a one-third reduction in stand will only reduce yield by 1% percent if it occurs before V8. Neighboring plants compensate to some extent for the lost plant.
For More Information
Hail Injury On Corn

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