Cotton futures dropped the most in two months on concern that textile mills will slow purchases, after prices reached a 15-year high.

The cost of cotton from the U.S., the world’s largest exporter, has averaged 79.4 cents a pound on ICE Futures U.S. in New York this year, compared with 53.68 cents during the same period in 2009. Higher costs may slow overseas shipments that the U.S. Department of Agriculture said Sept. 10 will jump 29 percent to 15.5 million bales in the year that began Aug. 1.

“The question in my mind is: Are we going to export as much as they say we are at these prices?” said Sid Love, the president of Joe Kropf & Sid Love Consulting Services LLC in Overland Park, Kansas. “The USDA may be overestimating demand for cotton.”

Cotton for December delivery fell 0.88 cent, or 0.9 percent, to settle at 93.62 cents a pound at 2:32 p.m. on ICE, the biggest decline since July 14. Earlier, the price rose to 95.79 cents, the highest level for a most-active contract since June 1995.

Cotton has rallied 49 percent over 12 months, fueled in part by unusually heavy rains that damaged crops in China, the world’s top grower and user, and by the elimination of import tariffs in Brazil because domestic supplies fell short of demand.

“The news is too bullish, and that makes me nervous,” said Keith Brown, the president of Keith Brown & Co., a brokerage in Moultrie, Georgia. Prices may need to drop 5 cents to 7 cents before the rally can resume, Brown said.

China’s weather will most likely start to dry out, said Joel Widenor, the director of agricultural services for the Commodity Weather Group LLC in Bethesda, Maryland.

“We’ve seen the worst of it,” Widenor said. A few showers over the next six to 10 days are “not enough to be a major issue,” he said.

China will likely harvest 32.5 million bales for the year ending July 31, compared with 32 million a year earlier, the USDA estimates. A bale weighs 480 pounds, or 218 kilograms.