Wheat surged the most in 5 weeks as investors bet the USDA would cut its estimate on worldwide supplies of grain on high demand and poor harvest.

The U.S. department of Agriculture is expected to lower its estimate of unsold supplies as of May 31 by 20 percent to 285 million bushels, according to analysts surveyed by Reuters news service.

The U.S. Department of Agriculture tomorrow will cut its estimate of unsold supplies as of May 31 by 20 percent to 285 million bushels, analysts said in a survey. Exports since June 1 are up 66 percent from the same period a year earlier, USDA data show, even as futures reached record highs last month.

Wheat futures for December, which had fallen nearly $1 a bushel since the month began, jumped to the daily limit permitted by the Chicago Board of Trade, settling up 30 cents at $8.83 a bushel.

In a sign of the strong pace of exports, the Commerce Department reported Thursday that the U.S. trade deficit fell to the lowest level in seven months, reflecting robust sales of wheat, soybeans and corn, as well as exports of industrial products. The deficit, or the difference between exports and imports, stood at $57.6 billion in August, down 2.4 percent from July.

A weak dollar has been a major boon to the country's export market, as foreign buyers shop for goods that to them seem relatively cheap. The greenback slid further against the euro, which bought $1.4194 late Thursday — slightly off its Oct. 1 high of $1.4284.