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