Rootless or "Floppy" Corn

June 21, 2001  8(14):97-98

Joe Lauer, Corn Agronomist

"Rootless corn syndrome" is increasingly becoming a more common root related problem diagnosed by farmers and crop scouts in recent years. Young corn plants (V3 to V8) are often leaning or appear ready to lodge.

Under favorable growing conditions, 4 to 5 sets of nodal roots develop above the seed and comprise the permanent root system of corn. The nodal roots are important in providing water and mineral nutrients that the corn plant needs for normal growth.

Before rootless corn is evident, corn plants may appear vigorous and healthy, but after strong winds, plants will fall over because there is no support. Leaning and lodged plants may also be wilted. These plants lack all or most nodal roots and appear stubby and blunt.

Rootless corn problems are usually caused by weather related conditions that coincide with development of the nodal root system such as hot, dry surface soils, shallow plantings, compact soils, loose, or cloddy soil conditions. Nodal roots will not grow into hot, dry compact soils. Also, the abrasive action of strong winds can break off secondary roots and inhibit establishment of the nodal root system. Excessive rainfall and shallow plantings may cause erosion and soil removal around the crown region that can result in rootless corn.

Herbicide injury (e.g. 2,4-D, banvel) and insect feeding (e.g. corn rootworm) may be a contributing factor to rootless corn, but generally there is little direct evidence of their direct involvement.

Poor root development may also occur in no-till fields that were planted when soils were too wet. In addition to likely compaction-induced root problems, abnormal root development may also occur because the furrow walls may have been smeared during the planting operation, preventing good seed-soil contact. If conditions turn dry, the walls of the furrow become hard and act as a barrier to root development. Roots growing in such an environment often appear flattened and under extreme conditions may result in plants' breaking and falling over during high winds.

Lodged rootless corn typically recovers with adequate rainfall that promotes crown root development. Cultivation to throw soil around exposed roots will aid the corn's recovery.

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