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.

Grain yield reduction in winter wheat with 100 percent of plants cutback to 2-3 inches above ground level.
Date of cutting	Plant height (inches)	Yield reduction (%)
May 3-14	6.5	9 to 13%
May 7-21	9.4	13 to 19%
May 9-28	11.7	15 to 36%
May 24-June 5	15.8	44 to 54%
derived from Afanasiev, 1967

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%
derived from Busch, 1975