RR wrote

snip
How close together did you plant the corn? Some sweet corn varieties
will not produce viable cobs if severely overcrowded.
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I planted two seeds per hole, in holes about 8-10" apart, in rows about 15"
apart, in raised beds with very rich soil and plenty of compost and mulch.

In one of the beds the corn is shorter and lighter green in color, and the
lowest leaves have dried and turned brown. The corn in this bed looked as
good as all the rest, at first, then it started to fade. I cultivated and
dug in a lot more compost to this bed a few weeks ago when I saw the change,
but it has not helped. The rest of the patch looks healthy and is a LOT
taller than any corn of mine has ever grown in prior years.