As of May 8th, USDA has South Carolina as 96% planted on corn and is on a normal track for progress.
Corn planting this year has been quite a process, with a majority of the crop going in the ground pre-April 1st and then was on pause for some time following Easter due to cold temperatures and rainfall events keeping planters out of the field.
Over the last few weeks we have had several calls on “yellow” and “purple” corn seedlings. Most of the corn in question was between V1 and V4 and had likely not had side-dress N applied yet. With the cooler than normal or cooler than we have been used to, night time and day time temperatures, heat unit accumulation has just been slow this spring. With little heat accumulation, root growth has been slow and nutrient uptake has been hindered, thus causing the nutrient deficiency symptoms that we have seen. Often these symptoms have been seen in fields where soil test levels are still average or above average for phosphorus.
In short, now that we have warmed up and plant growth has incresased, many of these visual symptoms have disappeared. IF fertility is of concern in these areas I would always suggest to pull both a tissue and soil sample and send to the lab.
A few other calls on small stunted and dying corn have come in, where areas or pockets of restricted seedling growth have been observed. In many of these situations interveinal chlorosis or striped leaves has been a symptom. In these situations I urge you to dig up plants and look at the roots. IF the roots are “bottle brushed” or do not have many secondary roots or root hairs I would highly encourage you to pull a nematode sample. This year, in a few of these situations, we have seen very high levels of sting and stubby root nematode in these areas. Unfortunately, the option to use a commercially available nematicide ended once the furrow had been closed. However, knowing what levels and species are in the field are going to be essential for future control and management decision making.
Last, as we approach V5 and beyond in our earliest planted corn, remember that N, P, and K uptake ramps up dramatically and many physiological processes intiate at that time in corn. Given that most of the P and K were likely applied pre- or at-plant, make sure that side-dress N is applied in a timely manner so that the crop has the N it needs, when it needs it.
If you have any questions or concerns please contact your local Agronomy agent.