Other commodities traded mixed, with crude oil ending slightly higher and gold, silver and copper all declining.
Heavy showers pelted parts of the Corn Belt on Wednesday, dumping a half inch to 2.5 inches of water over already-flooded parts of Iowa, Nebraska and Minnesota.
"It was even more devastating. It drowns out more corn and doesn't help the corn that didn't drown out," said Jason Ward, analyst with Northstar Commodity in Minneapolis.
Six weeks of rain have flooded untold acres of corn and soybean fields in the U.S. heartland, forcing farmers to abandon their crops and sending international food prices skyward. More bad weather is expected for Illinois, Indiana and Ohio on Thursday, forecasters say, meaning prices may could climb higher.
Corn for July delivery rose 5.75 cents to settle at $7.09 a bushel on the Chicago Board of Trade, after earlier rising to a new all-time high of $7.25 a bushel. It was corn's sixth straight trading record in as many days. Prices broke past the $7 barrier for the first time Wednesday.
Prices for the corn in the ground now jumped even higher. Corn for December delivery soared to a record $7.55 a bushel on the CBOT before falling back to settle at $7.395, still up 6.75 cents.
Farmers who have lost acres to flooding must now face a difficult choice: leave their fields idle and collect insurance payments or try their luck at growing soybeans, which have a later growing cycle but which also are vulnerable to overly wet soil. Farmers rarely plant corn past mid-June because crops would pollinate during the hottest time of the year, hurting yields.
"You pretty much have to assume that it's too late to plant corn," said Ken McCauley, a Kansas farmer and chairman of the National Corn Growers Association. Still, he added that planted corn could still produce good yields if the weather dries out in the near term.
"There are still an opportunity for profit" with $7 corn, he said.
But corn's spike has raised questions as to how long demand will support the unprecedented price levels. Livestock owners will likely be forced to slaughter more cattle, hogs and chickens to cope with rocketing corn-based animal feed, and ethanol producers who use corn as their main feedstock will also suffer.
"This is a price level here where I don't see a sector that can afford it," Ward said. "The livestock sector cannot afford the corn at this price, the ethanol producer cannot afford it and the dairy producer cannot afford it."
The flooding has also inundated the Midwest's soybean crop, pushing prices to near record levels. Soybeans for July delivery rose 20 cents to settle at $15.365 a bushel on the CBOT, after earlier rising to $15.455. The contract's all-time trading record is $15.96.