MERTZTOWN, Pa. — Donald Savidge would normally have sweet corn for the Fourth of July. But as with other produce crops, the corn was set back by April’s freeze that followed unusual warmth. The Berks County grower counts himself fortunate that he only lost a few weeks of early sweet corn, rather than the 80% to 90% crop loss reported by some fruit farmers. “It’s a shame,” he said. “It really hit this year so bad.