By Jeff Burbrink
I had reports of scattered hail damage in a few fields this week after some thunderstorms moved through the area.
The yield potential for hail damaged corn depends on the number of surviving plants per acre with a health growing point, the amount of leaf tissue lost during the storm, and the growth stage at the time the corn was damaged.
First, split a few stalks and see where the growing point is located. On plants at the V5 stage (5 collared leaves or less), the growing point was still below the ground. At V8, the growing point can be found about 1 foot above the ground, with a tiny tassel beginning to form at the tip. A healthy growing point will be white to yellow in color. If the growing point was damaged, it will have a watery appearance, and eventually will turn brown.
While you examine the growing point, also look at the stalk. Hail can cause bruising on the stalk, which interferes with water and nutrient movement within the plant.
If your target population was 36,000 plants per acre and the surviving plants have been reduced to about 30,000 plants by the hail, you can still expect 97 percent of the original yield despite the damage. At a population of 24,000, the expected yield would be 91 percent of the potential.
In addition to loss from a reduced stand, there can also be loss from lost leaf tissue. At the V6 stage, losses are about five percent if 60 percent of the foliage is damaged, and 11 percent of the foliage is completely stripped off. At the V8 stage, losses can be estimated at eight percent if 60 percent of the foliage was stripped, versus 16 percent if 100 percent of foliage was removed.
Soybeans are likely to survive hail damage if they have green leaves still attached. The plant can regrow from axillary buds located at the junction of leaves and stems. The larger the plant, and the more foliage that is removed, the slower the recovery will be.
Soybeans can tolerate a low plant population and still produce close to maximum yields. For instance, soybean populations can be taken down to near 100,000 plants per acre with minimal effect of on yield, and at 80,000 per acre, the yield may be reduced to about 90 percent of the maximum.
Being late in June, it is unlikely that replanting will help. Corn will not reach maturity (black layer) in most years, and soybeans will likely experience limited yields, even if you plant one maturity group earlier than we normally plant.
Because the plants are damaged, some people are considering a fungicide application to ward of disease. It is unlikely this will help. Most of the diseases that enter crops through wounds are bacterial and fungicides have no effect on these bacterial diseases.