Ferrie: Derecho Took 20 to 30 Bu. Off the Top of April Corn but Don’t Throw in the Towel

For many farmers in Illinois this week, the positive news is they got some much-needed rain on long-struggling crops on Thursday. The downside – in many fields the rain fell in tandem with 80 to 100 mph straight-line winds. 

The derecho-style storm knocked down fields of corn and even soybeans in parts of Illinois, Indiana, Iowa and northern Missouri. 
Corn nearing pollination will take the biggest hit to yield outcomes at harvest, according to Ken Ferrie, Farm Journal Field Agronomist, who’s based in central Illinois just south of Bloomington.

He says the fields most affected, much of which was planted in April, could see between 20 and 30 bushels per acre of corn knocked off final yield outcomes at harvest. 

However, he adds, those same fields were struggling so much this season from extreme drought they were on track to lose at least 40 to 50 bushels per acre of corn yield before the rain arrived.

“That inch of water will bring back a lot of those fields. It broke the bubble that was holding us in the drought,” he says.

Furthermore, he says the central Illinois forecast for the next week indicates some rain is likely to fall there during five out of seven days.

Read Tyne Morgan’s coverage of the derecho and its impact on Midwest crops here: Derecho Packs Punch of 100 MPH Winds, Flattens Cornfields and Crushes Grain Bins Across the Midwest

Short-Term Decisions, Long-Term Consequences
Ferrie encourages farmers affected by the storm to keep scouting crops and applying the nutrients, fungicides, insecticides and other inputs that might be needed.

“Be looking for silks in that corn crop that’s needing to get pollinated. You don’t want to lose silks to Japanese beetles or other silk clippers,” he says. 

Corn requires at least a half inch of fresh silk to pollinate. Under the extremely dry conditions, silk growth has been slow and pollen viability has been sorely challenged, Ferrie notes. 

With the storm damage that occurred, pollination could be more difficult to achieve in some cornfields, says Matt Duesterhaus, an agronomist with Crop-Tech Consulting who works with farmers in western Illinois and northeast Missouri. One of his concerns is that downed corn might have silks that are now on the ground and partially covered by vegetation.

“Corn is designed for the silks to come off the top of the plant like a fountain, so it can catch the pollen,” Duesterhaus says. “If corn’s on the ground with the silks shaded or covered over by corn leaves and stalks, that could make it a challenge for pollination to occur. It’s not something we can fix, but it is something that we want to monitor.” 

Ferrie adds that due to the unevenness of the corn crop across much of the region, it will take about two weeks for pollination to occur in some fields. 

 “In an ideal world, I like to see a whole field pollinate in three days, but that's a pipe dream in most fields this year due to the drought conditions we’ve had,” Ferrie says.

Read more about how to evaluate pollination here: Ferrie: Check Corn Pollination, Prepare to Spray if Heavy Pest Feeding is Underway

Stay On Top Of The Corn Crop
Thursday’s storm doesn’t make working with this year’s corn any easier, as farmers face trying to spray a crop that’s leaning at best and snapped off at worst.

“If it hasn't been sidedressed yet, a lot of farmers are probably going to have to switch gears and bring in an airplane and apply nitrogen from the air,” Ferrie says. “A lot of growers were waiting for the crop to get about shoulder height to Y-drop. Now, all of a sudden, that corn is twisted up and you can’t get through it by ground.”

But Ferrie emphasizes that if growers have a crop that stands back up and has some yield potential, they need to finish their planned agronomic program for it.

“Some of you are thinking about throwing in the towel and not spraying. That's what we call a walking away from a growing crop, and this is something you should never do,” Ferrie says.

Duesterhaus agrees and says he realizes some farmers might not want to spray their corn with a fungicide this year, because of the expense. “Another way to evaluate the situation is to evaluate the crop and try to determine what it’s worth? What yield potential is left out there to protect?” he says.

Beware Spider Mites In Soybeans
April-planted soybeans are a bright spot for a lot of farmers this season. Many of those early-planted acres are in full bloom across Illinois now. While the derecho flattened many soybeans, they are likely to rebound and do fine with time.

Ferrie is more concerned about the potential for severe spider mite infestations and recommends farmers watch for that problem this week and be prepared to treat.

“Beneficials help, but the big predator for spider mite is fungus,” Ferrie says. “Even with the rain, if this drought ticks on, we’ll have less and less fungus to take up the spider mites.”

Another concern is treating corn with a fungicide and adding an insecticide in the mix that can kill mites before there is an economic threshold present. 

“By the time the mites are a problem, your insecticide will have run its course and you’ll be spraying again and what’s available to spray isn’t what we had to work with 10 years ago,” he adds. “Today, most of our labeled products kill only the adults and don’t get the eggs, so you’ll be spraying again in 10 to 14 days.”

Ferrie says to talk with your retailer to put together a couple of plans, so you have options on how to handle a spider mite outbreak.

In the meantime, be scouting soybeans for the pest, Duesterhaus encourages. “If we get the rain they're calling for here and the temperatures stay moderate, we might be able to forget about spider mites, and they might not be an issue. But if it stays at 85-degrees plus with low humidity, they could come on strong and we’ll need to be ready to spray.”

To get the complete agronomic update from this week’s Boots In The Field report, you can listen to the podcast here.