NEW YORK — Food prices could rise next year because a hot summer probably damaged much of this year’s corn crop.

The U.S. Department of Agriculture said Monday a 672 million-bushel surplus of corn will be left over at next summer’s end. The estimate is down from last month’s forecast and below healthy levels.

This spring, farmers planted the second-largest crop since World War II. But “we just didn’t have a good growing year,” said Jason Ward of Northstar Commodity in Minneapolis. “It was too hot, too warm, too dry at the wrong time.”

Corn prices were relatively unchanged at $7.33 a bushel Monday. Down from a $7.99 peak in June, it’s nearly twice the price of last summer. More expensive corn boosts food prices because corn is used in everything from animal feed to soft drinks. It takes about six months for corn prices to trickle down to grocery store products.

But many food producers are being pinched by higher prices. Chicken producer Sanderson Farms Inc. had its third straight quarterly loss, in part because of rising feed costs. Hog producer Smithfield Foods Inc. said high feed costs would be a problem all year.

Traders worry grain shortages could return next year because of damaged crops.

Farmers expect a 920 million-bushel surplus when the harvest begins, the USDA said. That’s about a 26-day supply, a bit less than the previous month’s estimate.

But the USDA said the surplus could dwindle to 19 days. A 30-day supply is thought healthy.

First Published September 13, 2011, 4:30 a.m.