Potassium deficiency on incredibly good looking corn???
This time of year I often get pics sent on what looks like potassium deficiency on a lower leaf or two when the rest of the plant looks picture perfect.
What is actually occurring is that stalk diameter is increasing to a point where the lower leaf collars can't stretch enough to get all the way around the stalk. The plant is smart enough to know the leaf will soon fall off so it is pulling the nutrients out of the leaf before that occurs! Pics are from a plot where potassium levels are very high... No worries on this folks!!
@ottoscholl I agree I have had been blessed to travel to several countries and it's definitely eye opening. Especially my study abroad to Russia in college.