A monthly index of the economy in Iowa and nine other Midwestern states weakened in February, based on a survey of bank chief executive officers in rural areas.The overall Creighton University Rural Mainstreet Index declined to 51.6 in February from 55.9 in January, “Due to weak farm income, 40.6 percent of bankers reported that their banks had restructured loans while 3.1 percent indicated that their banks had rejected a higher percentage of farmland loans,” said Ernie Goss, the Creighton University professor who supervises and compiles the monthly survey.“Approximately one-fourth of bankers indicated no change in lending practices.” Borrowing by farmers remained weak for February.