Cool, cloudy conditions causing corn growth issues
The corn crop look sickly in a number of fields as the lack of sunshine and warm temperatures has limited photosynthesis and plant growth. Much of South Dakota’s corn crop has emerged and is between V1 and V3 stage even though some fields have been emerged for almost 3 weeks. The cool, cloudy weather have left some corn fields looking yellow with some purpling of stems. These symptoms should clear up with increased sunshine and higher temperatures.
Some leaf striping has been noted on some fields. The striping and general yellow color is often indicative of sulfur deficiency. However, these symptoms can also be seen on fields where sulfur has been applied. These symptoms will usually disappear by the fifth leaf stage (10-14 inches tall) with warming temperatures and have little effect on yield. If striping goes beyond this stage and sulfur was not applied, yields may be impacted. The yellowing caused by the cool conditions is more general over the field where sulfur deficiency tends to be more localized in certain areas of the field. Soil tests and plant tissue analysis can be used to confirm sulfur problems.
The other symptom commonly seen on corn in cool springs is purple stems and leaves. These symptoms can be caused by lack of phosphorus, but other factors causing purpling are cool nights and warm days, lack of root growth, and hybrid differences. Again, if phosphorus fertility is adequate, these symptoms will usually disappear with increased temperatures and seldom will lower yields.