Impact of Hail in Cereal Crops

Originally Published September 3, 2014

Impact of hail on cereal crops will depend on growth stage of the crop at the time of the hail event and the severity of damage.  In a study by R.H. Busch in North Dakota in wheat, the greatest yield reduction resulted when stems were broken in the milk stage, followed by anthesis, soft dough, boot, and hard dough stages – see Table below (Busch, 1975).

Grain yield reduction in spring wheat with 100 percent of stems bent.
Growth stage Yield reduction (%)
Boot (Zadoks 45) 28 to 39%
Anthesis (Zadoks 65) 15 to 60%
Milk (Zadoks 75) 30 to 70%
Soft dough (Zadoks 83) 16 to 55%
Hard dough (Zadoks 87) 3 to 47%
Table derived from Busch, 1975


Yield losses can also be directly attributed to shattering of the mature crop.  A simple and rough estimate of grain loss requires the use of a one-foot square frame:

  1. Pick a typical area of the field.
  2. Place a 1 ft by 1 ft (inside dimension) box on the ground and count the kernels found within the box.

A one (1) bushel per acre loss equates to 20 wheat kernels per/ft2, 14 barley kernels/ft2 and 10 oat kernels/ft2.  Keep in mind that this is a ‘fudge factor’ but for the purpose of rough field estimation is an adequate estimate.

Remember to please contact your hail insurance provider for their procedures in assessing hail damage as they may be different than what has been provided here.

Source:  Busch, R. H. 1975.  The effect of simulated hail injury on spring wheat. North Dakota AES Bulletin 497. 18 pp.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

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