Spiraling Sub-Surface SeedlingsSpiraling Sub-Surface SeedlingsMore than one report of incomplete corn emergence has been received with accompanying descriptions of mesocotyls and coleoptiles that are twisted, corkscrewed, spiraling, and otherwise 'messed up' below the soil surface. The end result of such spiraling sub-surface seedlings is either underground leaf emergence or eventual death of the seedling. As is usual with crop problems, several culprits can cause this symptom and afflicted growers need to identify which is the most likely cause in their situation.
Restricted Emergence: Corkscrewed mesocotyl/coleoptile development often results when the coleoptile encounters resistance as the mesocotyl elongates. Such resistance can be caused by severe soil crusting, a naturally dense soil surface, or cloddy soil surfaces. A combination of severe sidewall compaction plus press wheel compaction over the furrow can also restrict coleoptile emergence.
Herbicide Injury: Certain
herbicides, notably cell growth inhibitors, can affect seedling shoot
development especially if weather or soil conditions are not conducive for
rapid growth. Quite often when herbicide is part of the blame, significant soil
crusting is also a major factor.
Temperature Response: Some years ago, I came across an article from Rhodesia (Buckle & Grant. 1974. Rhod. J. Agric. Res. 12: 149-161) that described the exact same phenomenon and attributed it to large diurnal fluctuations in day and night temperatures. Abnormal mesocotyl/coleoptile development occurred when temperatures fluctuated from daytime highs of about 80 degrees F to nighttime lows of about 55 degrees F. The data also suggested that extended periods of cold stunted and distorted seedling growth.
For other information about corn, take a
look at the Corn Growers Guidebook on the World Wide Web at
http://www.kingcorn.org