A new report says a May survey of business supply managers suggests economic growth will slow over the next three to six months in nine Midwest and Plains states.The report issued Monday says the Mid-America Business Conditions Index dropped to 54.3 last month from 55.9 in April. The figure was 58.2 in March. Creighton University economist Ernie Goss oversees the survey, and he says tariffs and flooding have harmed several states.The survey results are compiled into a collection of indexes ranging from zero to 100. Survey organizers say any score above 50 suggests growth. A score below that suggests decline. The survey covers Arkansas, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma and South Dakota.