Storm-Battered Midwest Crops Need A Triage Plan

A mere month ago, corn and soybeans were off to a strong start. However, heavy rainfall and hail over the past week have changed the landscape in some parts of the Midwest, including central Illinois. As fields there slowly dry out, Farm Journal Field Agronomist Ken Ferrie is urging farmers to shift into triage mode to address nutrient deficiencies, rising disease pressure and looming weed problems.

In storm-hit cornfields, Ferrie notes that reading the specific colors of the crop is a good first step to executing a rescue plan. He says farmers in parts of central and northern Illinois are currently seeing three primary color patterns in corn, each one signaling a different nutrient issue.

1. Oxygen Starvation and Root Injury

In low-lying, water-saturated spots, Ferrie says entire plants are turning pale green to yellow from top to bottom, with lower leaves taking on an almost orange tint. This is a direct sign of oxygen starvation and root injury. Many of those plants, Ferrie warns, will die or remain largely non-productive if soil and weather conditions do not improve quickly.

2. Sulfur Deficiencies

Elsewhere, corn plants are green at the field surface with yellow tops and distinct striping in the leaves. Ferrie says this is due to a widespread sulfur deficiency.

“Some of the worst fields I’m visiting are ones where growers pulled the dry out for cost savings and then forgot to replace the ammonium sulfate,” he says. On those acres, he recommends adding ammonium thiosulfate (ATS) into a sidedress pass to rebuild the sulfur supply and availability.

3. Nitrogen Shortfalls

A third pattern — light green plant tops with lower leaves showing burning down the midrib — signals a nitrogen deficiency. With a long way to go from now to black layer, Ferrie stresses that farmers cannot afford to let corn “sit idle” without adequate nitrogen (N). He advises pulling soil nitrate samples in these fields to accurately quantify the shortfall and make sidedress applications.

Don’t Let Weather Steal The Sidedress Window

Persistent rains have slowed or stopped sidedressing in many areas, leaving some growers dangerously behind schedule. That occurrence is a key reason why Ferrie advises putting about two-thirds of total nitrogen on early in the season, then using sidedress or late-season applications to fine-tune a fertility program. Relying on a single, late sidedress application that sudden, inclement weather can block leaves the crop entirely exposed.

Where fields remain too wet to carry ground equipment or run pivots, Ferrie says it’s time to implement Plan B.

“If you’re waiting for your field to dry out so you can put nitrogen on through your center pivot, it might be a good time to think about flying some N on to hold this corn until you can get dry enough to run the pivot,” he advises.

If the corn grows beyond the reach of standard sidedress tools by the time soils finally firm up, high-clearance applicators or aerial urea are the most viable alternatives. He recalls similar conditions in 2015, when some growers used aerial-applied urea after 16 inches of rain.

“In the fall, that paid big dividends,” Ferrie notes.

Beat The Rush For Planes And Fungicides

The window for aerial nitrogen is limited, Ferrie cautions. As the season progresses, aerial applicators will need to pivot to make fungicide applications for tar spot and northern corn leaf blight. “I don’t think there’s any way around that,” he says, anticipating significant disease pressure. This means growers who intend to use airplanes for nitrogen applications must move early, before aircraft are fully booked for fungicide jobs.

Some farmers are also considering adding fungicide to their postemergence herbicide passes in corn to save on application costs. Ferrie says that can make sense, provided it is viewed strictly as a supplement.

“If that’s not going to replace fungicide at VT and/or R3, it might be a good approach,” he says. He frames postemergence tank mixes as a smart way to stretch dollars, but not as a substitute for well-timed VT or R3 fungicides where tar spot and other foliar diseases are a major concern.

Soybeans: Consider Nodulation, Disease And Weeds

Once the worst of the nutrient stress is addressed in corn, Ferrie turns farmers’ attention to soybeans — many of which have endured hail, sat in water-saturated soils, and now face elevated disease and weed pressure. Despite the damage, his underlying philosophy remains the same: “My motto is: never walk away from a growing crop. The key is a growing crop,” he says.

In areas hit hardest by hail, early-planted soybeans have likely lost much of the yield premium they typically enjoy from early flowering. Ferrie still expects many of those fields to recover, but no longer as the top-end yielders they likely once were.

“Think of them more as mid-May beans now,” he says. “I think our premium was wiped away in the storm.” He adds that the hailed fields also now have a thinner canopy, which will become a critical issue later as soil-applied herbicide residuals fade and weed pressure increases.

Yellow Beans And Dead Nodules

Many soybean fields are showing yellowing in low-lying areas, leading some farmers to ask questions about a potential “carbon penalty.” At this stage, Ferrie says the true issue is oxygen and the loss of Rhizobia bacteria. Beans at this point should be fixing much of their own nitrogen, but they aren’t because of how long the crop has sat in water.

“When you look at the nodules on these beans, they’re black, not pink, indicating that poor to no nitrogen is being produced,” he says.

Because Rhizobia are aerobic, they cannot survive extended saturation, and Ferrie expects populations to rebuild only after fields finally dry out. He estimates it could take 10 days to two weeks after it completely quits raining for nodulation and nitrogen fixation to return.

Fusarium Wilt And “Lazarus” Plants

On soybean disease calls, Ferrie says Fusarium wilt is the most common problem he is seeing right now. He says plants can look “perfectly healthy on Monday and be completely wilted by Friday,” with little visible lesion on the stem above or below the soil line.

The diagnosis comes when growers split the taproot and small roots, finding a brown center and poor nodulation. In some cases, plants respond by pushing out white roots right at the soil surface, and Ferrie has seen those fields make a surprising comeback. “They sometimes have what we call a Lazarus moment and recover,” he says.

However, if there is no new root growth in the plant, he expects those plants to stay wilted and “crunchy.” On the agronomic upside, losing plants this early gives neighboring soybeans the time and space to branch out and help compensate for the stand loss.

White Mold Risks In Beans At R2

With many early-planted soybeans in central Illinois now at full R2 and conditions remaining cool and wet, Ferrie sees a high risk of white mold, particularly in fields with a known history of the disease.

“I don’t think there’s any way around white mold,” he says. “If you have fields with a history of white mold, now might be a good time to start initiating some of the white mold sprays.” That puts fungicide applications firmly in the “do now” category for those fields, rather than making them a wait-and-see decision.

Be Uncompromising On Weed Control

Ferrie urges growers not to delay postemergence weed control in stressed or flowering beans, including non-GMO acres. Some farmers are reluctant to spray for fear of knocking off flowers, but he notes alternatives are essentially unavailable.

“The question that gets asked is, ‘Won’t I knock off the flowers like on my non-GMO beans if I spray now?’ Yes, but you don’t have any options unless you own a row-crop cultivator and have a bean-walking team lined up,” Ferrie says.

Loss of canopy from hail and stand reduction, combined with limited soil residuals, sets up ideal conditions for waterhemp and other tough weeds to explode. Ferrie emphasizes that even on fields that may ultimately be zeroed out for yield by insurance, farmers still need to control weeds to avoid building next year’s seedbank. Skipping weed control on abandoned acres, he warns, simply “builds our weed bank for next year.”

Hear more of Ferrie’s recommendations for storm-battered corn and soybeans in this week’s Boots In The Field podcast, available at the link below.