The proclamation issued Saturday is part of an effort to help the state's corn and soybean harvest. The move suspends the hours of service requirement for truck drivers who are carrying propane.
Culver says that means fuel will get into the state quicker and into the hands of farmers who are drying their crops after this year's harvest.
The proclamation takes effect immediately and runs through roughly the end of the month.
On Oct. 1, Culver issued a proclamation that lifted the weight restrictions on highways for corn and soybeans for 60 days.
The governor has issued the temporary exemptions for several years to help farmers.