Chicago Board of Trade corn futures closed down on Friday, pressured by improved planting weather in the US Midwest this week, analysts said. Forecasts called for drier weather, which should allow farmers to pick up the pace of planting, in the northern half of the Midwest. CBOT May corn settled down 3/4 of a cent to $3.57 per bushel. The CBOT May corn hit a three-week low in early moves at $3.56-3/4 a bushel.