Hail Damage in Small Grains
May 18, 2000 7(9):52
Joe Lauer, Corn Agronomist
The kind of damage and amount of loss due to hail is determined in part by the crop
growth stage. Before jointing, small grains are least susceptible to hail damage.
The spike is still below ground and protected from injury. Hail damage occurring
during jointing or the boot stage is difficult to assess. Spikes can still pollinate
and fill, and regrowth from new tillers can occur. The greatest yield reduction
from hail damage occurs in the milk stage near Zadoks 75 (Busch, 1975). Hail damage
occurring at other growth stages from boot to ripe kernels (Zadoks 45 to 90) is
variable and further influenced by environmental conditions following the hail damage
(Afanasiev, 1967).
The National Crop Insurance Association uses two methods for assessing hail damage
to small grains. One method involves counting the number of lost spikes, damaged
spikes and lost kernels. The other method estimates damage to nearly ripe grain
when shatter of kernels from the spike is the primary loss.
Let the crop recover for 5 to 7 days before assessing the remaining small grain
stand. Adequate time does remain for planting soybeans or some other alternative
crop, if the small grain stand is no longer economically viable.
References
Afanasiev, M. M. 1967. The effect of simulated hail injuries on wheat. Montana
AES Bulletin 613. 27 pp.
Busch, R. H. 1975. The effect of simulated hail injury on spring wheat. North
Dakota AES Bulletin 497. 18 pp.
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Grain yield reduction in winter wheat with 100 percent of plants cutback to 2-3 inches
above ground level.
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Date of cutting
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Plant height (inches)
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Yield reduction (%)
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May 3-14
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6.5
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9 to 13%
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May 7-21
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9.4
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13 to 19%
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May 9-28
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11.7
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15 to 36%
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May 24-June 5
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15.8
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44 to 54%
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derived from Afanasiev, 1967
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Grain yield reduction in spring wheat with 100 percent of stems bent.
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Growth stage
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Yield reduction (%)
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Boot (Zadoks 45)
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28 to 39%
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Anthesis (Zadoks 65)
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15 to 60%
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Milk (Zadoks 75)
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30 to 70%
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Soft dough (Zadoks 83)
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16 to 55%
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Hard dough (Zadoks 87)
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3 to 47%
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derived from Busch, 1975
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