The condition of the U.S. corn crop has deteriorated slightly, with 72 percent in good or excellent condition as of May 27 compared to 77 percent on May 20, due to warm, dry weather that has increased stress on plants in parts of the Midwest and South, according to the U.S. Department of Agriculture.

The percentage is still well above the 63 percent rating good or excellent at the same time in 2011. “Everyone is worried about the hot, dry weather pattern in May continuing into June,” said Emerson Nafziger, an agronomist at the University of Illinois in Urbana. “I doubt we have compromised our yield potential at this time with timely rain next month.”

Corn futures for July delivery fell 2.8 percent to settle at $5.625 a bushel on May 29. The most-active contract has fallen 11 percent in May on speculation that farmers will harvest a record crop in 2012. Production will rise 20 percent, to 14.79 billion bushels, as farmers plant the most acres since 1937 and yields expand to a record 166 bushels per acre, said the USDA on May 10.