Why is my corn purple or yellow?


It’s been a challenging growing season to date in Ontario, and the rough conditions in May and June are showing up in corn rows. Got funky-coloured corn? The cause all comes down to root growth.

Peter Johnson, RealAgriculture agronomist, says that early-planted corn that went in fit to un-fit is yellowing, sometimes row to row. The yellowing is from wet feet and restricted root growth, Johnson says, leading to a lack of nitrogen (N) uptake.

For those that waited until June to get the corn in are seeing another hue in the field — purple. Are purple plants phosphorus deficient? Sort of, Johnson explains, but again, this is because of root development and a lack of plants’ ability to access the nutrient not because it isn’t there.

Soil conditions sometimes varied row-by-row for corn planting in 2019. Hampered root growth is showing up now. (Supplied)

“That early planted corn, emerged uniformly, but now we start to see where it was fit to plant and where it was pushed,” he says. “Plants are lemon yellow, smaller, shorter, and struggling.” The purple plants don’t have the root structure to feed the plant the water and nutrients it needs. There are even reports of drought stress symptoms showing up — a testament to how tough conditions were when the crop went in.

Some areas saw over 15-inches of rainfall from in the planting window, “It’s surprising any corn got planted at all,” Johnson says.

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