Wheat futures fell the most in four weeks on speculation that favorable weather will boost crop prospects in Australia and the U.S., the world’s top exporter. Corn and soybeans closed unchanged.

Parts of Oklahoma, Texas and Kansas, the top U.S. wheat growers, got as much as 0.75 inch (1.9 centimeters) of rainyesterday, data from World Ag Weather show. Areas in eastern Australia received as much as 2 centimeters this week, boosting soil moisture before planting starts next month, a farm group said.

“The U.S. crops are getting some beneficial moisture, and wheat only needs a little rain to produce a good crop,” Shawn McCambridge, the senior grain analyst for Jefferies Bache LLC in Chicago, said in a telephone interview. “Unless there are production problems outside of the U.S., the demand for U.S. wheat will be routine.”

Wheat futures for May delivery fell 2.1 percent to close at $6.955 a bushel at 1:15 p.m. on the Chicago Board of Trade, the biggest drop for a most-active contract since Feb. 27.

The price gained for a fourth straight week, the longest rally since October, after U.S. crop conditions deteriorated this month and turmoil in Russia and Ukraine triggered supply concerns.

Corn futures for May delivery were unchanged at $4.92 a bushel. The grain rose 2.7 percent this week and is approaching a bull market after domestic demand for animal feed rose and export sales doubled from the U.S., the top shipper.

Soybean futures for May delivery closed unchanged at $14.365 a bushel