Over the last few days, hail has been reported in several areas of Manitoba, potentially impacting cereal crops. Assessing damage will take a few days, and impact will largely depend on stage of the crop and how severe the hail event was, i.e duration of storm, size of hail.
Generally, cereal crops prior to stem elongation can recover from hail, even if there is substantial leaf damage as the growing point is below the soil surface and will likely not be damaged.
Hail damage occurring during stem elongation or the boot stage can be difficult to assess. Spikes can still pollinate and fill, and regrowth from new tillers can occur. Generally speaking, hail causes the greatest damage to small grains from the boot stage through later stages.
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|
Remember to contact your hail insurance provider for their procedures in assessing hail damage as they may be different than what has been provided here.
Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture