You may not find it in every field, but unless you've been blessed with rains, even during the hottest days, odds are you can find a hybrid or field where you can find an inch or more of cob that doesn't have any kernels on it this year. In the seed industry, they refer to that as 'tip back.'
Mark Lawson, Syngenta agronomist based near Danville, Ind., says it's been showing up even in good hybrids. He believes it's simply a function of weather conditions. Extremely hot days in late July and early August, along with dry conditions in many areas, have contributed to ears aborting kernels.
When you do yield checks in fields, one of the parts of the formula is number of kernels per row on each ear. Even if you've got 34,000 ears and 18 rows of kernels, if you've only got 35 kernels per ear instead of, say, 38, you're going to see a yield drop.
In fact, if you run that example through the standard yield formula that relies on ear count, average number of rows of kernels and average number of kernels per row, you will see the difference fairly quickly. In this example, three kernels less per row on each ear is worth 20 bushels per acre, from 258 to 238 bushels per acre. That assumed 34,000 ears per acre and 18 rows of kernels on each ear.
When crop reporters for the Indiana Ag statistics Service return to the same fields where they counted stalks for the August estimate, they may run into fields where tip back has occurred. When they plug fewer kernels than assumed into their formula, it could affect the final yield estimate determined for Indiana, and sent to USDA to make up the national estimate. The question will be how widespread tip back actually is.
The other thing that could hurt final yields is how much starch is packed into kernels before the black layer forms. That party is already over in many fields in Indiana. Where it's not over, extreme heat and dry weather isn't conducive to causing the plant to signal that more starch should go into each kernel. The plant's goal is to produce as many viable kernels as possible, not necessarily the highest yield per acre.
Stay tuned for further reports to determine how widespread might be within Hoosier cornfields.