COOKED WHEAT: Dry, hot temperatures in the U.S. and a drought in Russia had investors anticipating that supplies might be tight. Wheat surged 5 percent, corn rose 4 percent.

GOLD, OIL SLUMP: Crude oil closed at the lowest level since November and gold slid to the lowest since December. A surge in the dollar was a big factor behind both moves.

THE BUCK: The dollar has been climbing sharply over the past two weeks as worries about Europe continue. Political gridlock in Greece has increased the chances that the country may be forced out of the euro bloc.