Todd Burrus of the Illinois-based Burrus Seed Company wrote on August 24, 2022 that now is the best time to see the top retract before corn cobs and tops shrink back during the coming month as they dry out. “The reality is that the plant is expected to support more cores than it can complete… Not every core will make it to the finish line,” he wrote.
Hybrids will also have genetic differences to stress, he said. And the timing of the key stress can trigger different responses. “Realize that if that stress point is eliminated, the product with more kickback may have been the winner in other locations or other times of the year. Imagine two people running in the heat. One will inevitably get further than the other. The reasons for this can be limitless,” he said.
High yielding growers will even say they leave the yield on the table when the ears are completely filled to the brim. A spike of about 1.2 cm can be a sign that plant populations are dialed for some growers, Quinn agreed.
Despite this, Quinn asks all farmers to get out and pull the ears to check the progress of the grain filling.
“Farmers might be surprised after doing some yield estimates at how much there is out there, even if they see a tip back,” Quinn said. “Ear size is determined around V6 to V15 or up to a few weeks before pollination. Many of the fields challenged this year may still have some decent ear sizes.
“The lost yield potential for each missing kernel per row in an 18-row corn hybrid (assuming a final ear count of 28,000 ears per acre) is approximately 6 bushels per acre,” said Quinn. “So, yes, yield losses from barren dumps can add up.”
However, he points to a bulletin (https://www.agry.purdue.edu/…) by Bob Nielsen, emeritus corn specialist at Purdue University, which states that the number of ears harvested is around 600 for many hybrids. Hybrids whose spikes are typically 16 rows in circumference tend to set about 36 to 40 nuclei in each row, while those that typically develop 20 nuclei around them tend to set closer to 30 nuclei per row.
“If the potential ear size (number of ovules) was quite large to go for pollination (favorable pre-pollination conditions) but failed to pollinate the top silks, the resulting ears can still have 30 to 40 grains per row, although it 1 to 2 inches gives barren tip. In other words, the ear size harvested will still average around 600 grains and the final grain yield will be average to above average.
“On the other hand, if kernel counts show only 20 to 25 kernels per row with long, barren cob tips, then this indeed indicates that the crop has suffered from significant stress conditions, probably more than once during the season. Grain counts per ear will be as high as less than 600, and final grain yield in this last example will likely be less than average for this field and/or hybrid,” Nielsen wrote.
There’s no way to improve kernel counts this late in the season. The question is what to do with what’s left. “Let’s hope the temperatures behave and we can increase the grain fill time a bit to fill what’s out there,” Quinn said.
Monitoring reject fields from now until harvest is a good idea, Burrus added. Plants with scarce resources for full reproduction often rob those resources from the rest of the plant, compromising viability.
You can find more information about the tip back at: https://www.dtnpf.com/….
Pamela Smith can be reached at [email protected]
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