As a result of weaker farm economic conditions, bankers in the Midwest expect nearly 1 in 5 crop farmers will experience negative cash flows this year, according to a regional rural economy index. The Creighton University Rural Mainstreet Index sank to 39.8 for July from June’s weak reading of 43.9. The monthly survey polls bank CEOs in rural areas of a 10-state region dependent on agriculture and energy. The index, which ranges between 0 and 100, with 50 being growth-neutral, had improved for four of the last five months but has remained below 50 for 11 consecutive months. The July index for Iowa sank to 51.9 from June’s 59.1.