In a season marked by uneven corn development and delayed soybeans, Farm Journal Field Agronomist Ken Ferrie is telling growers to lean on in-season management rather than write fields off.
“Don’t walk away from a growing crop. Stay the course,” encourages Ferrie, who’s based in central Illinois.
Speaking on his latest Boots In The Field report, Ferrie lays out five priorities for farmers’ consideration now.
1. Diagnose what’s causing “yellow” corn: sulfur vs. nitrogen deficiency.
Ferrie says most cornfields in his area are progressing well, but ponded areas are concerning. He is telling farmers to make an accurate diagnosis what the problem is before applying additional nutrients.
Yellow on the upper leaves with green tissue below points to a sulfur deficiency, while pale plants from top to bottom with lower leaf cannibalization down the midrib signal a nitrogen deficiency. Some fields of corn show both.
“Adding nitrogen to a sulfur deficiency won’t fix that problem,” Ferrie says, urging growers to use plant photos and quick nitrate tests to sort out the issue.
He adds that some ponded corn crops are so stunted they are “not worth saving,” but others still have yield on the table if fertility needs and stress are addressed now.
2. Consider using ponded and replant areas as a chance to pivot.
With “a large amount of double-crop beans” going in behind wheat, soybeans and even corn, Ferrie wants farmers to be proactive in addressing ponded out areas.
“If possible, I recommend planting something in these ponds to help manage the weeds and rebuild the soil biology after being drowned out,” he says.
Where ponded areas in the middle of fields are inaccessible without damaging a good crop, Ferrie advises seeding covers by drone.
Soybeans, he notes, are rebounding much more slowly than corn after saturated soils because growers must “rebuild the soil biology, especially Rhizobia, then the root system, then the nodules.” Even so, he expects visible improvement in many ponded areas within the next week, especially if weeds are controlled.
3. Reassess rootworm strategy: “catch crop” risk is real.
Ferrie reports substantial rootworm feeding in central Illinois cornfields, including in fields planted with traited hybrids. He and his team are finding four to seven larvae per plant and as many as two full nodes of roots missing, especially in fields north of Bloomington.
“When you find this feeding, one thing is clear: your current insecticide plan is not working, whether that’s crop rotation or traits,” he says.
“If you sprayed twice last year to control southern rust and tar spot and had some of the greenest corn in the neighborhood, your green crop became the neighborhood catch crop for corn rootworm,” he adds.
What transpired is fungicide programs kept the corn crop green in some areas. Both northern and western rootworm beetles concentrated in that green corn to feed and lay eggs, setting farmers up for higher rootworm pressure this year.
Ferrie cautions growers who want to drop traits or insecticide “to save money on rotated acres” without hard scouting data. Sticky traps in beans alone can be misleading when beetles concentrate in greener corn.
“Pest teams paying attention to sticky traps in both crops in late August and doing root inspections, looking for feeding, are all good tools to help us make the call on what we can do to cheapen up our rootworm control,” he notes.
4. Treat pollination as “go time” for insect scouting.
With April-planted corn in central Illinois currently pollinating and May corn 10 days to two weeks out, Ferrie calls this “go time for all pest teams.” He wants close scouting for silk-clipping insects.
Uneven stands, water damage and replanted fields create extended pollination windows that allow beetles to migrate from plant to plant and from main fields into replanted areas.
“The more strung out the pollination, the more trouble we have,” Ferrie says, warning that many growers replant ponded acres but “forget to watch the silk clipping and end up with poor pollination.”
He adds that drones can be a practical tool to treat isolated ponded areas at their later pollination timing without damaging surrounding crops.
5. Delay fungicide unless current disease pressure demands it.
Tar spot, northern leaf blight and weather-related issues like physoderma brown spot are already showing up, but Ferrie does not want growers pulling the fungicide trigger early in otherwise healthy fields — especially while pollination is still uneven.
“Without heavy disease pressure, I would monitor pollination to be sure we don’t have to deal with the beetles or the aphids to get this crop pollinated,” he says.
Spraying too early, he warns, can create extra trips.
“Jumping the gun too soon with your fungicide could cause you to have to go back and clean up the insects,” Ferrie says. “Many of these fields will pollinate uneven due to water damage, so wait for the ponds to get pollinated before you pull the trigger.”
Ferrie wants pest teams to keep monitoring disease pressure as weather evolves, but to give priority to securing clean, complete pollination before layering on fungicide where pressure is still relatively light.
You can hear more of Ferrie’s in-season agronomic recommendations in his latest Boots In The Field podcast at the link below. Be sure to hear the details on the upcoming Farm Journal Corn & Soybean College July 21-22 at the Crop-Tech Consulting campus in Heyworth, Ill. The event features two days of unsponsored, in-depth agronomy — classroom sessions plus hands-on field time. You can learn more and sign up here.
