Many Louisiana corn producers took advantage of the warming trend that took place in mid- to late February this year to plant their corn, and who can blame them? The soil temperatures were between 55 degrees and 60 degrees, the 10-day forecast made no mention of a risk of frost or freezing, and there was plenty of soil moisture.
It turns out there may have been a little too much soil moisture in some cases. LSU AgCenter staff members have received numerous calls about stunted and nutrient deficient corn in which the symptomology appears to get worse as the crop progresses.
Upon closer inspection, a pattern reveals itself where there will be several rows of “good” corn that is developing normally and has a dark green, healthy appearance, followed by a row or series of rows of stunted corn with nutrient deficiencies appearing in the lower leaves.
Most often the symptoms appear to be potassium deficiency, with light yellow to necrotic leaf edges on either side of a green midrib. In almost every case, the grower has applied some amount of potassium, albeit often in the fall of the previous year.
What these fields have in common is that the stunted rows are always adjacent to the tractor tire paths through the field. The compacted soil may have resulted in a shallow root system that is incapable of absorbing adequate levels of potash. There is no doubt these corn producers went out and checked their fields in February to be sure the ground was dry enough, but with the high soil variability in Louisiana, there were sections of these fields that are low spots and may have held too much moisture when the planter tractor passed through that part of the field, and compaction occurred.
Often the corn plants are growing out of the bed at an angle, and have very shallow root systems. The high uniformity of the affected corn and it being observed row-to-row seems to indicate that herbicide injury is not to blame.
Usually during the conversation on the turnrow, the grower or consultant agrees that it may have been a little wet in places during planting. These affected rows of corn will likely not yield at the same level as the unaffected corn, and there is little that can be done on a practical basis to rehabilitate the crop. It may be that this turns out to be one of those hard lessons learned.