This week in the Boots In The Field podcast, Ken Ferrie addresses a variety of agronomic issues impacting late-season corn and soybeans across parts of the Midwest.
Here are three of his key takeaways:
1. Nitrogen deficiency is showing up in corn fields, and is extreme in some areas. In many cases, the N deficiencies are enough that Ferrie is able to see them from the road, as plants have yellowed all the way up to the tassels. He recommends checking fields to consider what an insufficient amount of N at this point in the season will mean to yield results.
“Plants running out of N at R4 run the risk of tip abortion,” he notes, as a for instance. “At R5, tip kernels are going to get light, and if it’s a D hybrid, it’s going to cost you in late fill.”
Reflecting on the two nitrogen-friendly years of 2022 and 2023, Ferrie notes that 2024 nitrate samples indicated farmers had lost some nitrogen and needed to replace it.
On top of that, many growers also bumped up yield goals this season, which given yield projections for this fall, that looks like it was a good decision.
“We can see now that bumping those N rates was the right thing to do,” says Ferrie, Farm Journal Field Agronomist. “The more N you had on last fall or early this spring (some of which was lost), the more we had to bump those rates.”
In some cases where farmers bumped up their N applications, they could have been pushed even higher.
“Going through R5, we could see some of these big ears wanting to tip early due to the weight of the ear and long ear shanks. The heat this week will make this even more visible,” he says.
If temperatures drop and some rain comes through for farmers, many of those affected ears will straighten back up. But if the ears tip over due to weight before black layer occurs, that will affect kernel fill and final yield results.
“Many fields have top kill in the corn plants, and it is more evident with stress,” Ferrie says. “The later it shows up, the less damage it’ll do to yield. But if we lose those top three leaves too early, it’ll lighten up the kernels on the top one-third of the ear.
“If you’re running out of nitrogen, you will become a victim of top kill,” he contends. “If you’re deep into R5, the effect will be a lot lighter on you.”
2. More variation is showing up in soybeans: Across parts of Illinois, Ferrie says he is seeing more sudden death syndrome (SDS) along with dry weather stress. The combination is impacting soybeans now in the reproductive stages and is speeding up their maturity.
“We’re seeing the early-planted beans in the drier areas showing some stress and starting to actually change color,” says Ferrie, adding that some of the stress is compaction related and some is a pH issue.
“In some of the higher pH pockets, how far along the soybeans are will play a big role in how much the stress affects the yield,” he says.
3. Pest problems and some disease issues need immediate attention:
Stink bugs: Ferrie says to be on the outlook for stink bug populations. He says to be vigilant in checking soybean seed acres.
Impacted seeds may be smaller, shriveled, and/or discolored, he notes. Damaged seeds may also produce stunted seedlings.
Tar spot: More corn growers are seeing tar spot popping up in their crop.
“Most corn I’ve been in looks like it’s going to make it the black layer, but the plants may be trashed by that time,” Ferrie says.
“Other areas seem to be somewhat clean of tar spot. I do expect that to continue to change as we’re finding tar spot in the upper portions of the plant, indicating that it’s on the move,” he adds.
Southern rust: The disease is becoming more of a problem in the Midwest this year. Temperatures that reach 80°F-plus during the day in combination with warm nights and high humidity will kick up the amount growers will see in affected crops.
Efficacy ratings for corn fungicide management of southern rust have been compiled by a working group of corn researchers and can be found here: Fungicide Efficacy for Control of Corn Foliar Diseases
You can listen to the Boots In The Field podcast for this week here: Episode 341: Boots In The Field Report
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