"I always get worried when the suckers are one third or half as big as the whole corn plant; I keep thinking of all the nutrients that must be going into the sucker!"
Like I mentioned those "suckers" are leaves and they make food to feed the plant. I can't bring myself to believe that they take anything from the main stalk, or are in competition with it. I do believe that they add to the overall ability of the plant to make food. Leave them be.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-