The heat wave has finally broken, for how long we don’t know. The lack of rain persists though. These two factors have really hurt the corn crop, which we touched on last week. Now for more details.
According to Chad Lee, University of Kentucky Grain Specialist, the latest USDA-NASS crop progress report said that 66 percent of the corn was silking last week. He thinks that that leaves a small percentage of corn acres in Kentucky that have a chance to make decent yields.
So how can you tell if your corn has pollinated or not?
A quick way to determine how many ovules are fertilized within about 10 days after pollination is with the ear shake method. With this method, use a sharp knife to cut through the husk, but not the cob, from the base of the ear to the tip. Gently remove the husk from the ear, taking care to not remove any silks. Once all husks are removed, gently shake the ear.
The silks of fertilized ovules should fall off. If an ovule was not fertilized, then the silk will remain on the ear. Repeat this method several more times at different areas in the field to determine how well the field of corn pollinated.
Lee says that dry conditions will have the greatest impact on corn that was tasseling and pollinating during the drought. Pollination requires the release of pollen from the tassels and capture of that pollen by the silks. The pollen then travels down each silk to fertilize the ovule.
Dry weather will reduce pollination in a couple of ways. First, dry weather will delay silking and could result in pollen dropping before silks are exposed. Second, dry weather will cause the silks to dry out quicker and reduce the ability of the silks to capture and move pollen to the ovules.
Temperatures near 100 can kill pollen. Nothing can be done to regain unfertilized ovules after pollination. Adequate moisture following poor pollination will help the fertilized ovules develop kernels, but yield losses are certain with poorly pollinated corn. Yield losses from a drought during pollination can be as high as 100 percent but more often the yield losses are much less.
By about two weeks after pollination, the corn should reach the blister stage and fertilized kernels should be visible. From the blister stage on, pollination success can be determined by examining the number of developing kernels on each ear.
Corn undergoing drought stress prior to pollination still has many chances to regain most of the yield potential. However, if adequate moisture occurs by pollination, the corn plant probably will recover and yield losses can be as little as 5-10 percent.
Fertilized ovules develop into kernels and the first stage of this development following pollination is the blister stage. Dry conditions during this stage could result in aborted kernels. Aborted kernels are shrunken and white compared to plump, developing kernels.
Kernels at the tip of the ear are most susceptible to abortion. The developing kernels will progress through the blister, dough and dent stages before reaching physiological maturity. The kernels are gaining weight during the dough and dent stages. Water is a key component to kernel weight gain.
Dry weather during the dough and/or dent stages will reduce final kernel weight and reduce yields. Dry weather will reduce yields more during the dough stage than during the dent stage.