Gov. Gretchen Whitmer is asking the federal government to approve Michigan farmers for disaster assistance because of wet weather that's making it hard to plant crops.

Whitmer made the request Wednesday in a letter to U.S. Agriculture Secretary Sonny Perdue.

Michigan is going through one of its wettest periods on record, with nearly 38 inches of rain between May 1, 2018, and April 30.

As of June 9, only 3.5 days this year had provided proper conditions for field work. About 63 per cent of the state's corn crop had been planted, down from 88 per cent on the same date in 2018. Less than half of the soybean crop had been planted.

Soggy fields also have prevented harvesting hay for livestock.

Officials say 64 of Michigan's 83 counties are seeking disaster designations.