Moderate to extreme drought now covers about 53 percent of the Midwest, the country’s main growing region, fueling crop- price gains that are the biggest this year among the 24 commodities tracked by the Standard & Poor’s GSCI Spot Index. The rallies are boosting costs for companies from McDonald’s Corp. (MCD) and Coca-Cola Co. (KO) to Archer Daniels Midland Co. (ADM) and Smithfield Foods Inc. (SFD)