Speculators increased bullish bets on agricultural commodities by the most in a month after a U.S. heat wave increased speculation crops were damaged, adding to mounting concern that global supply will fall short of demand.

Hedge funds and other speculators raised their net-long positions across 11 agricultural futures and options by 6.7 percent to 675,561 contracts in the week through Aug. 16, U.S. Commodity Futures Trading Commission data show. Bets on soybeans rose 25 percent and those on corn 9.6 percent. Wagers that wheat prices will decline were cut by the most in a month