WASHINGTON — A key measure of wholesale inflation rose in July by the most in six months. The measure, called core wholesale inflation, excludes volatile food and energy prices. It surged 0.4 percent last month. But most economists say they aren’t concerned about the increase. One reason is that it was driven largely by costlier tobacco products and pickup trucks, which economists say are probably one-time events. Raw material prices also fell in July. Those figures should lead to lower wholesale prices in coming months.