Occasionally there will be a season when corn sporadically develops colored kernels on ears. There are several possible non-disease causes for colored kernels. The affected kernels should not influence grain grading if the embryo remains undamaged. …
Every spring, farmers throughout the Corn Belt are frustrated and concerned when they see newly emerged corn with a purple tinge. The purple coloring is often caused by fallow syndrome, says George Rehm of the University of Minnesota. “This occurs in areas where a crop was not grown last year or is following sugar beets,” he explains.
“Fallow syndrome involves an understanding of a symbiotic relationship between the corn plant and a group of fungi called mycorrhizae. It’s a ‘you scratch my back, and I’ll scratch yours relationship,” Rehm says. “The mycorrhizal fungi develop around the corn roots and help the roots take up nutrients. Mycorrhizal fungi are usually associated with uptake of phosphorus and zinc.”
Mycorrhizal fungi reaches a minimum following a non-host crop like sugar beets or where no crop has been grown. Likewise, repeated tillage of soil where a crop was not grown last year can produce fallow syndrome. For example, fallow syndrome may appear where heavy rains flooded soybean fields, and the area was repeatedly tilled to control weeds.
Once your corn plants exhibit symptoms of fallow syndrome, Rehm says there’s really not much you can do about it. As temperatures warm and soils dry, the purple coloring usually disappears, but by that time your crop has likely lost significant yield potential.
Rehm says a banded application of phosphate fertilizer near the seed at planting can help prevent the problem. He recommends a banded application of 20 lb. P205 per acre at planting.
Another option is to inoculate your seed with an appropriate symbiotic fungus. Inoculant company Philom Bios offers a fertility management seed treatment called JumpStart. The product is a formulation of the naturally occurring soil fungus – Penicillium bilaii. It comes bottled as a wettable powder that is applied to the seed before planting. Much like the symbiotic mycorrhizal fungi described by Rehm, the fungi in JumpStart colonize plant roots. From there they produce organic acids that break the mineral bonds that hold phosphate to the soil.