If you planted corn in mid-May and notice it looks a little lazy or folded over, it's time to do a bit of scouting. Reports of "rootless corn" or "floppy corn" syndrome are cropping up, particularly in central Illinois, eastern Iowa and eastern Missouri.

It's a condition in young corn plants (typically at the V2 to V5 growth stages) where the permanent nodal (crown) roots fail to properly develop. The scenario may cause lingering challenges to the crop during the growing season and at harvest.

University of Illinois plant physiologists Fred Below and Connor Sible said in an interview with DTN that the development happens when environmental stress coincides with plant growth. They said in this case, the planting conditions and other circumstances at planting may have seemed normal, which makes scouting for the condition even more critical.

"We've had some reports of rootless corn and narrow planting date window of planting of May 12 to May 16 seems to be consistent in the reports with May 14 at the apex," Sible said. "We think it has to do with a stew of environmental conditions right at that time when the plant is making key decisions.

"As the plant grows toward the soil surface, it starts to respond to light and should set the crown just below the soil surface. However, we had above normal temperatures and several extremely cloudy days just as it was trying to detect light and missed the opportunity to set the crown where it should be," he added.

Below noted that the condition is not hybrid specific. "The reports we have is it is in different genetics and from different management systems. These are fields that had generally good conditions, that were planted into mellow soils and there is no evidence of herbicide injury."

Lance Tarochione, a technical agronomist with Bayer based in west central Illinois, has seen the syndrome in his region. In severe cases, it has been significant enough to justify replanting, he noted.

DIG TO DISCOVER SYMPTOMS

"It's more about when the plant emerged than when it was planted, but we don't always have that date," Tarochione said. "Normally, the nodal root system begins to develop at the V2 growth stage. Often, we do not notice a problem until plants reach the V5 growth stage when they are big enough to no longer support themselves. Plants begin to lean or almost look like they are lying on the ground at an extreme angle and it's because they don't have a crown root system to hold them upright."

Until plants get big enough to start leaning over (V4-V5), the syndrome is easy to miss during scouting, unless you dig plants to inspect the development of the nodal roots, he added.

"You've got to dig plants and look at the crown. Often the corn plant has been able to grow a couple of crappy nodal roots to hold itself up. But as the plant begins to put on leaves, it starts to flop," he said.

The crown of the plant should be located three-quarters of an inch below the soil surface. "In the plants I'm concerned about, the crown is literally at the surface at the soil," he reported.

Corn plants can compensate with additional nodal root growth, if they have moisture, Below observed. But doing so redirects energy that would have otherwise been used by the plant to grow leaves, and leaves intercept light and carry out photosynthesis providing energy for plant growth and yield potential.

Stalk breakage, goosenecking and lodging are other potential side effects of rootless corn depending on rainfall and the wind. Sible explained that when problem fields encounter droughty conditions, they can be more prone to stalk breakage in a wind event. Rain can help support continued root growth, but too much rain and wind can lead to lodging or goosenecking of stalks.

"We know that young corn plants are making yield decisions every day, so not having the crown in the right spot is probably not a good idea," Sible said. "But deciding to replant at this stage is also a tough decision."

THREE NEXT STEPS

Tarochione noted that there are three options if you discover corn with rootless syndrome.

"Ignore it and hope for the best," he said. "Or, you can tear it up and replant. Or if you are really lucky and have the right soil conditions and a good cultivator, you can move loose soil up around the base of the plant to attempt to bury the plant a little deeper.

"Farmers in other areas of the country use cultivation with success. It requires loose soil be moved around the base of the plant. Here in Illinois, we get a lot of crusting and rolling a dirt clod over the plant isn't going to help it," he said.

With heat units piling on and the calendar moving toward mid-June, the decision to hope for the best or pray for rain without wind has typically been the go ahead move.

"I guess we had enough people praying for rain because we got a lot of it. But we also got a lot of wind. So now the important thing is to watch those fields carefully throughout the season, especially as we approach harvest," Tarochione said.

Find more information on rootless corn from the following sources.

Iowa State University:

https://crops.extension.iastate.edu/…

Ohio State University:

https://agcrops.osu.edu/…

Purdue University:

https://extension.entm.purdue.edu/…

Bayer:

https://www.cropscience.bayer.us/…

Pioneer:

https://www.pioneer.com/…

Pamela Smith can be reached at pamela.smith@dtn.com

Follow her on social platform X @PamSmithDTN

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