Hail and Wind Damage Assessment Resources at Penn State

Del Voight – Penn State Extension

When it comes to the middle part of the season there is always a risk of wind and hail damage to crops. Many times there only a handful of growers that experience significant crop losses, however, to this growers there is nothing more disheartening then to find a crop dessimated by mother nature.  We had a straight line wind event and golf ball sized hail a day ago at about 3 in the afternoon. By 430 I was receiving calls to determine the best course of action.  In most cases I would prefer to wait a week and then go and check due to the fact that over the years I have learned that in most cases there is an exaggerated assessment immediately and a week of growth can really make the difference in determining options.  But with local government agencies needing some initial assessment I decided to go out the day after and check.  I assessed several fields in the most affected area and most if not all the corn that was hailed on though dramatic will grow through it with minimal impact.  I use  the hail damage fact sheet more to illustrate to producers the impact and try to sort through how the crop will react.  Penn State Hail Damage Assessment and options.  Young corn prior to V9 will take allot of leaf removal before a yield impact.  In my experience with 20% damage growers assume it is a complete loss when in fact at that level little to perhaps a 4% damage might result. Again refer to the Hail Damage Assessment worksheet to balance research with applied use in the field.
There are other factors with light now shining to the soil more weeds might germinate. The damage to the tissue might allow infection of leaf diseases and the crop might be delayed in maturity.  So there is the need to inspect fields and make decisions to assist growers in determine additional management to alleviate these concerns whether it be an application of a fungicide and or another run over the field to apply additional weed control products.
Disease risks associated with hail damage(Source Illionois Extension via Corn and Soybean Digest)
It is important to remember that a fungicide application cannot recover yield potential lost due to hail damage. Fungicides protect yield potential by reducing disease. There are some diseases of corn that are favored by wounding, e.g., Goss’s wilt, common smut and stalk rot. Similarly bacterial blight and bacterial pustule on soybeans are favored by wounding. Fungicides are not effective against the pathogens that cause these diseases. The foliar diseases that are managed by fungicides (e.g., gray leaf spot, northern corn leaf blight, eye spot and common rust on corn, and brown spot and frog eye on soybeans) are caused by pathogens that do not require wounds for infection. These foliar diseases will influence the yield response to fungicides more so than hail damage.

On Left should be fine fine larger corn on right had 10% snapped corn and 30% defoliation will be left to go to harvest

In a few cases where the plant is broken below the grower point from a one two shot of hail and wind resulting in green snap then we get into a replant condition which then requires questions on what herbicides were applied which affect the options for replant and also if corn itself can be replanted. It also brings to the forefront what to do with the existing crop I have seen corn killed with a fatty acid inhibitor such as Poast and replanted within a day turn out to be a satisfactory option when small. Large corn with 14 leaves however creates a whole other matter of dealing with a forage that will need to be mowed, wilted and combined with a starch to help with fermentation. Two years ago a grower bush hogged tasseled corn and had to wait for the fodder to dry before no tilling could commence to adequately cut the fodder. There are many facets to this issue that not alot of research exists.

Wind blown corn with green snap on majority 40%  of plants and some 50%  that are leaning.  Considering replant

The wind areas that I observed and walked into present another challenge.

This field is leaning over roots are intact and there is little green snap. Should rise back up will check in  a week.

 Some fields are simply leaning over and the roots are firmly attached while in other cases the roots are pulled up.  Green snapped stalks indicate the show is over same with the corn with the roots torn out. The leaning corn in most cases will right itself if done prior to tasseling and be acceptable for harvest.  At this point growers need to asses what percent of the stalks are snapped? % with roots torn from soil? What is the planted population?  All of these factors need to wieghed to make a decision. Today I observed a field with 9 foot corn about V13 with 30% snapped off with a population of 42,000ppa of corn that would leave about 28,000ppa leaning so in the end we would best leave the crop for a week and most likely it will be acceptable to go to harvest. A field less than a mile away about the same stage of growth had 30,000 ppa and had 50% green snap with 50% leaning with about half the field affected so in that case it might be prudent to consider harvesting  and replanting.
The take home here is that typically the damage is not as dramatic as it may seem.  By checking some key factors such as percent damage, root and stem fitness and most important stage of growth a better management decision can be arrived at that is acceptable given these types of events.