Ferrie: 3 Agronomic Problems to Look For This Week

A number of farmers have been sending Ken Ferrie pictures of dead corn plants scattered throughout their corn stand. Dead plants can come from several things, and he says the important thing to do now is to identify the cause now while you can still find the evidence. 

Dead plants now can be the result of disease, wireworm, grubs or fertilizer burn, to name just a few of the problems in fields. 

“So we need to dig these plants up and take a look at those plants to figure out the problem,” says Ferrie, Farm Journal Field Agronomist and owner of Crop-Tech Consulting, Heyworth, Ill.  “By fall, the symptoms will be long forgotten, and most growers won't correlate yield loss to the events happening in their fields right now.”

While you’re looking at the gamut of issues, Ferrie says more and more farmers in the Midwest are seeing wireworm damage affect early-season corn growth.  “That's a problem at the top of the list, and we’ll need to change our insecticide program to get ahead of wireworm next season,” he says.

Here are three additional problems Ferrie is telling farmers to look at in cornfields now:

1. Is It Ugly Corn Syndrome Or A Carbon Penalty?
Much of the corn crop in central Illinois is transitioning into the so-called ugly corn phase – that's when the seed roots handoff to thetrue roots. If everything goes as planned you won't see any hesitation and growth. But if anything has interfered with crown root development, you'll see cornfields go from a crop that’s uniform in color to one that has reduced uniformity in color and height. The longer the ugly corn period lasts, the more it will affect yield. 

Along with that issue, with warming temperatures, the corn crop is entering into what Ferrie calls the carbon penalty. 

He explains that as the soil biology wakes up, it consumes soil nitrates, sulfates and phosphorus and, in the process, this can lock up plants’ growth and development and show up as yellowing corn plants. Ferrie says how yellow and how long the corn stays yellow will depend on your carbon load and carbon location. Here are two questions he says to ask yourself: Is the soil residue worked in or is it on top? And, how did you manage your nitrogen, phosphorus and sulfate applications? 

“The carbon penalty will affect all different corn sizes and is different than the ugly corn stage,” he says. “You can have perfect crown root development and bypass the ugly corn stage and still get caught in the carbon penalty.”

Ferrie says now is a good time to evaluate your 4R approach to nitrogen and sulfur. If you mastered your 4R approach, the corn will roll through this period without slowing down. This also is where the timing and placement of products come into play. 

“Having nitrogen, sulfur and phosphorus near the plant to keep it growing can help while the carbon penalty happens in the soil around it,” he says. “Be aware that the longer corn stumbles in the carbon penalty, the bigger effect it will have on yield, especially for your G and L1 hybrids.”

Ferrie says all hybrids flex – a process of losing yield potential, due to stress.  Based on hand-harvested hybrid studies, Ferrie has determined when hybrids flex and also where in terms of number of rows of kernels, ear length and depth of kernel as well as what stage. Here are the four ways hybrids flex:

•    Girth (G): Flex in girth (number of kernels around) occurs from V4 to V6.
•    Early Length (L1): Flex in length happens from V6 to V15.
•    Late Length (L2): Flex in length takes place between R1 and R3 (tipback).
•    Depth (D): Flex in kernel depth occurs from R3 to R6.   

Learn more about the problem of the carbon penalty here: Ferrie: Beware the Carbon Penalty in Cornfields Now

2. Rootless Corn Syndrome 
To identify this problem in fields, Ferrie says to look at your corn at V3 to V5 to determine whether it’s starting to lean in different directions as it gets taller. 

If that’s what you identify, be aware that these plants are still thriving off the seed roots. They look healthy but will tend to lean as they become heavier with growth, and they aren’t developing crown roots. 

Several things can contribute to rootless corn syndrome:
1.    When the surface soil is dry that can stop crown roots from developing. 
2.    If you didn’t firm the soil above the seed that can make the problem worse.
3.    The problem can develop in parts of the field where you had to rotary hoe to break the crust to help the crop emerge. In the process, that let surface moisture get away. 

The fix for rootless corn is rain or irrigation to stimulate crown roots so they fire off. 

“Those of you that have irrigation be sure to check the crown root development. If it's lacking, fire up that irrigator even if that corn looks good,” Ferrie advises.  “For the dryland acres, we need to pray for rain to get these crown roots going.”

Learn more about the rootless corn syndrome here:  Rootless Corn Syndrome Cause and 'Cure'

3. Herbicide Carryover
There is some carryover damage showing up in corn this season in central Illinois. While the crop will shake it off with time, there is likely to be some yield loss in the G hybrids, Ferrie says. 

“At the other end of the spectrum in some of the heavy rain event areas, we're seeing residual herbicides dinging soybeans that are trying to emerge. “Let's watch these fields close and make those replant calls quickly if we need to,” he advises.

To hear all of Ferrie’s agronomic recommendations for this week, listen to the Boots In The Field podcast here: