US: Growers find purple corn

But, if the plants don’t change back to their normal colour, growers will have to determine if a nutrient deficiency or some other issue may be causing the issue, said Peter Thomison, an Ohio State University Extension agronomist. OSU Extension is the statewide outreach arm of the college.

Corn seedlings can take on strange hues for environmental reasons, but will change to normal healthy green after several days of 70 degree or higher temperatures, Thomison said. But they also might turn yellow due to low nitrogen uptake or limited chlorophyll synthesis or purple due to reduced root development, he said
“If your plants stay yellow in hue or are dying, then it may be a serious problem that may call for replanting considerations,” Thomison said.

Conditions that can cause colour changes to corn crops include:
· Environmental conditions such as high rainfall amounts that causes saturated soils, can lead to the appearance of yellow corn. Excessive water leads to poor respiration of the roots inhibiting nutrient uptake. After the soils dry out, the appearance of the corn should return back to normal.

· Cool temperatures at night combined with wet fields and high radiation levels during the day can result in purple plants in some cornfields. The purple tint is more attributable to the production of anthocyanin, which is a plant’s response to a stress or a combination of stresses.

· If corn follows a fallow season, a root fungus called mycorrhizae reaches a low population. Mycorrhizal infection of corn aids in phosphorus and zinc uptake. Until the fungal growth is stimulated by the corn roots, which exude starches and sugars, the plant may stay purple color for a while.