Rootless Corn Syndrome
May 30, 2012 by Kevin Gale, CCA
The first crop condition report came out last week showing the corn crop off to one of its best starts in history. Corn in good to excellent condition was rated at 77% nationwide. Illinois was reported at 79% good to excellent. However, crop issues such as seedling blight, ponding due to heavy rains, drought conditions and now rootless corn syndrome have contributed to the decline in the good to excellent corn condition rating to 72% nationwide. Illinois is now rated 66% good to excellent, a drop of 13% in one week.
Rootless Corn Syndrome
Rootless Corn Syndrome or "floppy corn" has occurred this year in response to dry soil conditions. Hot temperatures and windy days with low humidity has inhibited or slowed the development of nodal roots of corn plants. Following some wet periods and/or planting into soil still a little on the damp side this spring, soils have dried out down to the crown where nodal roots are initiated near the V3 growth stage. These nodal roots will grow in response to gravity as long as soil conditions, including moisture, are hospitable. If these roots elongate into dry surface soils they run the risk of drying out before finding moisture and dying (See Figure 1). When this happens, the young plant must survive on seminal root contributions and anything left in the seed energy reserves until later nodal roots find their way to moisture. Normally, the seedling is fed by seed reserves and the seminal root system until the nodal roots take over around V5 to V6. "Floppy" corn is observed when seedlings without normal nodal root formation are tipped over from lack of support. In severe cases, plants may lay down completely on the soil surface and the mesocotyl breaks leading to a dead plant.
Rootless corn syndrome has been associated with shallow planting, open seed slots, furrow erosion and smeared sidewalls with dry/loose dirt on top. Row cleaners run aggressively can also add to the problem where side walls were smeared with the disk openers in wetter soils. Heavy rainfall events lead to more water running down seed trenches resulting in shallow seed placement and crown development.
Unfortunately, little can be done to correct the problem. Rainfall is the best bet to help generate new nodal roots. Cultivation can be a good practice to throw dirt up around the base of plants that are still standing, but may not help those that are already lying down. Cool temperatures forecasted this week should buy us some time while we await additional rainfall.
Figure 2 - Dried out nodal roots.
Figure 3 – Normal Nodal Root Development vs. Rootless Corn Syndrome.