Diagnosing Corn Emergence Issues
It’s a happy day when the corn starts coming up. Make sure you go out a few times and inspect it. You’re more likely to catch any problems and make a diagnosis when the symptoms are readily visible. Check for patterns of seedling emergence, uniformity of the stand, and color of the leaves.
Jeri Geren is a diversified ag and natural resources Extension agent at Kansas State University. She says if the corn comes up fine then suddenly wilts or even dies, suspect root damage.
"There are some insects like the wire worm and white grub, they will feed on the roots and sometimes they will cause severe damage to the roots and not allow those plants to continue uptaking nutrients and moisture," says Geren. "Sometimes if you have plants that came up but they looked yellow and wilted, it could be due to a compacted area in the field, of if it’s poorly drained."
Corn leaves that suffer freeze or frost damage will look like they’re water soaked, then turn white. Plants can recover from this, but if it was so cold that the roots were frozen, they will die.
Geren says leaves that start turning yellow might indicate a nutrient deficiency, but it also depends on where the discoloration is.
"If you’re seeing yellow discoloration in the bottom of the older, lower leaves, that’s usually an indication of nitrogen, whereas the opposite would be with a sulfur deficiency, you see yellowing kind of in the newer, younger leaves," she says. "Potassium also has yellowing discoloration, but it’s usually on the leaf margin."