ST. PAUL — Gov. Mark Dayton is urging the federal government to step in on railroad delays hitting Minnesota grain farmers.

A growing backlog of railroad shipments cost corn, wheat and soybean farmers $109 million in lower prices this spring, according to a University of Minnesota study. With harvest approaching, Dayton on Wednesday asked the Surface Transportation Board, a major federal railroad regulator, to press freight railroads to address the issue.

Dayton said recent plans to tackle delays released by BNSF Railway, Minnesota’s largest freight carrier, don’t have enough information to soothe the state’s concerns.

Farmers and some politicians have blamed railroad companies for prioritizing oil shipments from North Dakota over agricultural products, while railroads say the brutally long winter has caused issues.