Mich. Comp. Laws § 168.52

Sec. 52. A general primary election of all political parties shall be held in every election precinct in this state on the Tuesday succeeding the first Monday in August preceding every general November election in which a governor is to be elected, at which time the qualified and registered electors of each political party shall vote for party candidates for the office of governor. This section shall not apply to parties required to nominate candidates at caucuses or conventions.