USDA's National Ag Statistics Service reports 81% of the planned corn acres were planted by May 9, and 39% had emerged—both well ahead of the 62% planted and 21% emerged five-year averages.
In Iowa, almost half the corn had emerged; Minnesota, a third and Michigan, a fourth. Were young seedlings killed by frost? You generally need to wait three to five days after the cold weather event before you can accurately assess the extent of damage or recovery, according to Bob Nielsen, Purdue University agonomist. "Injury to the crop can look very serious the day after the event or even two days after the event, but recovery is likely if there is no injury to the growing points of the affected plants.”
Frost by itself is not a guaranteed "kiss of death" for young corn. As long as the growing point of the young plant
is still protected below the soil surface, the injured plant usually recovers from the effects of the superficial leaf damage. For more detailed explanation, see "Frosty Corn, Toasted Plants
As of May 9, soybeans were 30% planted, versus a five-year average of 19%; only 7% had emerged.