Assessing Hail Damage in Corn

Joe Lauer, UWEX Corn Agronomist

This past Tuesday evening, an intense storm with hail and high winds swept through northern Wisconsin. Some hail damage has been reported in western Wisconsin. Any corn knocked down by wind will likely recover since it is still early enough in the growing season and the stalk and leaves are still green.

Hail affects yields primarily by reducing stands and defoliating the plant. Defoliation causes most of the loses. Knowing how to recognize hail damage and assess probable loss is important for decision making.

The keys to storm related damage of crop fields are to: 1) be patient, 2) determine the crop growth stage, and 3) assess plant health accurately. Go ahead and view the damage, but do not make any assessments until 7-10 days have passed because it is difficult to distinguish living from dead tissue immediately after a storm, It will take that long for the corn plant to begin growing again if it can. For guidelines on assessing hail damage click here.

Hail adjusters use standard tables to calculate compensation for yield loss associated with hail. Four assessments are made on corn when hail occurs after silking (Vorst, 1990) including:

  1. Determining yield loss due to stand reduction,
  2. Determining yield loss due to defoliation,
  3. Determining direct ear damage, and
  4. Bruising and stalk damage.

It is important to work with your crop insurance adjuster before any final decisions are made.

Further Reading

Lauer, J.G., G.W. Roth, and M.G. Bertram. 2004. Impact of Defoliation on Corn Forage Yield. Agron J 96:1459-1463.

Roth, G.W., and J.G. Lauer. 2008. Impact of Defoliation on Corn Forage Quality. Agron J 100:651-657.

Vorst, J.V. 1990. Assessing Hail Damage to Corn. National Corn Handbook NCH-1:4 pp.

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