P&PDL Picture of the Week for
November 4, 2013

Floppy Corn Syndrome

RL (Bob) Nielsen, Purdue Agronomy

Excessive drying of the upper soil profile is conducive for the development of the so-called “rootless corn” or “floppy corn” syndrome. This problem is most commonly caused by the timing of initial nodal root formation in excessively dry soil. If nodal roots begin their elongation in bone-dry surface soil and reach adequate soil moisture at deeper depths before the meristmatic root tip desiccates, then the root will survive and proliferate. If the root tip (and its accompanying meristem) desiccates prior to reaching soil moisture, the entire young nodal root will likely die. The appearance of such a desiccated root is what one would imagine; shriveled and discolored. This symptom is unlike that of any other lethal root stress, including salt injury from fertilizer. These symptoms are NOT like any associated with herbicide injury or insect feeding. Because several sets of roots may not have formed belowground, the crown may "appear" to be at or above the surface. Entire sets or “whorls” of nodal roots sometimes die in this manner and the plant essentially survives on what’s left in the kernel reserves and what the seminal roots offer in terms of moisture and nutrient uptake until the next set of nodal roots develop and become established.The aboveground appearance of a plant affected with the “rootless” syndrome can remain fairly normal up until the windy day when the mesocotyl simply can no longer support the plant and it flops over to the ground. Obviously, the health of the mesocotyl and the seminal roots determine whether an affected plant can “hang on” until a decent soaker occurs to replenish soil moisture levels.

For more information, see my online article at http://www.kingcorn.org/news/timeless/FloppyCorn.html.

Click image to enlarge

Floppy corn plants in field

Floppy corn plants in field

Absence of established nodal roots

Desiccated and dead nodal roots

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service