Thunderstorm Season Adds Another Risk to Corn

Ability to survive hail depends upon timing.

Her mother and father still live in northern Oklahoma. One time this spring the Hoosier housewife got a frantic call form her dad. A storm carrying big hail was headed their way. It was time to take action. While severe storms early in the spring are more routine in Oklahoma, storms carrying damaging hail and wind are no strangers to most of the Corn Belt, especially in late May through June. That's just about the time corn should be above the ground and ready to take off.


Farmers who have endured hail storms and who have reported to Farm Progress in the recent past say the number one thing to do after a hail storm is be patient. Wait a few days before making the call. Ask your seedsman, chemical dealer, and Extension agent to help you assess damage. But give the field four to five days to recover before making a call as to whether you need to replant or leave the field. By then plants that looked badly damaged the night of the storm may be showing signs of recovery. Occasionally, they won't, and then you know that your yield will be greatly reduced.


One such farmer in Indiana a few seasons ago called out everyone mentioned, walked the field, did population counts, and was convinced he might get 70 bushels per acre. Because it was in late June, he decided to leave the field anyway. Whether it was perfect weather from then on out or whether corn has more ability to recover than the crop was given credit for, the field ended up yielding nearly 135 bushels per acre. The farmer was glad that he made the call to leave it in this case.


If you are unlucky enough to have one or more field hit by hail, a big determining factor may be whether the growing point is above the ground or not. It typically comes above ground around the V5 to V6 stage. This means there are 5 or 6 leaves with leaf collars fully exposed. Until the growing point is above ground, in theory the entire plant above ground can be destroyed and the plant will still grow back. But once the growing point is above ground and it's damaged, the plant won't regrow- it's finished.


A good source to help make decisions about whether to leave a field or not after hail is the Purdue University Corn and Soybean Field Guide, 2009 edition. A staple in the eastern Corn Belt for some 30 years, this 300 page or more guide that fits in a shirt pocket contains loads of information which helps make decision-making in the field and scouting for problems both much easier. Check it out or order a copy at:


The guide contains a chart which shows hoe much leaf defoliation it takes at various stages to result in yield loss at the end of the season. The amount ti takes is likely to be surprisingly more than you think, especially early in the season. Consult all your support people, plus the guide, before making your leave or tear up decision.

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