Cotton prices jumped the most allowed by ICE Futures U.S. after the worst floods in half a century damaged crops in Australia, the world’s fourth-largest exporter.

Crop losses total about 300,000 bales, and damage may worsen if wet weather continues, the Australian Cotton Shippers Association said today. The industry group had forecast record production of more than 4 million bales before the floods. Prices have almost doubled in the past 12 months as growers struggled to meet rising demand from China.

“News from Australia is certainly not good,” said Mike Stevens, an independent trader in Mandeville, Louisiana. “The market is all stirred up.”

Cotton futures for March delivery rose by the exchange limit of 4 cents, or 2.8 percent, to settle at $1.4725 a pound at 2:41 p.m. on ICE in New York in the biggest gain since Dec. 21. The price touched a record $1.5912 on Dec. 21.

For the year started Aug. 1, the U.S. is forecast to be the largest exporter, followed by India and Uzbekistan, government data show.