Every year somewhere in Southern Ontario someone experiences frost injury.Though small corn like that shown here on June 5th can withstand a significant frost and regrow without much problem the same cannot be said of corn that reaches the 6-7 true leaf stage. When a hard frost penetrates the whorl on larger 6-7 true leaf corn the dead decaying plant tissue of the whorl behaves as a rotting bottlekneck to the growing point trying to push out new living plant tissue.Just pray that you never have to diagnose frozen corn around the 15th of June.Its one of the hardest calls you'll ever have to make.