Things To Consider When Hail Hits Corn This Time Of Year

Things To Consider When Hail Hits Corn This Time Of Year

In determining yield loss due to hail damage, look at percent of leaf area destroyed; also consider stalk and ear husk bruising and harvest issues.

Hail and wind damaged corn and soybeans in a large area of northeast Iowa in late July. Hail storms again devastated portions of Iowa's corn crop on Aug. 9—this time in north central Iowa. Storms cut a 1 to 8 mile swath across north central Iowa. Farmers who had cornfields in its path are now asking, "How does hail that strikes corn plants after tasseling affect yield?"


Roger Elmore, Iowa State University Extension corn agronomist, says most corn in the area of Iowa hit by the August 9 storm was in the blister stage (R2). According to hail industry tables, complete leaf loss at R2 results in 73% yield loss (see table). "The amount of leaf loss as well as the development stage of the corn plant greatly impacts losses," points out Elmore.


For example, if half of the leaves are lost, yields are reduced by 22%.  Damage at tasseling, which is the VT stage of growth, affects yield more severely while losses both earlier and later in development are less severe.


Table.  Estimated percent yield reduction caused by hail damage.

Consider a few other things relative to hail damage


Elmore says there are also a few other things you should consider when evaluating hail damage to cornfields.

• Stand losses also occur with hail storms. Yield losses are directly related the number of plants broken below the ear at these later development stages. For example a 10% stand loss – plants broken below the ear will result in a 10% yield loss in addition to any losses from defoliation.

• You'll likely have more stalk rot. Bruises on stalks and ear husks may allow pathogen entrance, thus further reducing yields and increasing issues with stalk weakness and grain quality problems.

• Don't apply fungicides to try to help this situation. No research data supports fungicide applications as a method to improve crop recovery.

• If a portion of the crop is worth harvesting, adjust combines well. Volunteer corn will likely be a problem in 2010 whether this year's hail damaged crop is harvested or not.


"These losses are devastating," says Elmore. "Prior to the storm, the crop looked better than ever. Recovery of the crop, and the growers, will be difficult."


For more information see the article on assessing hail damage from the National Corn Handbook .  In addition, ISU Extension has developed and posted resources for farmers affected by hail on a special Web page on the ISU site.

TAGS: Extension
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