A milk promotion program shall provide for assessments against producers of the affected commodity to defray the cost of the activities provided for in the milk promotion program. Assessments authorized in a milk promotion program shall be based on quantity of commodity marketed and shall be assessed against all affected producers. The maximum assessment levied on the commodity of any affected producer shall be not more than fifteen cents per hundred pounds of milk produced and sold by that producer. After the first 5 years the program is in operations, 500 producers of milk by petition, with at least 10 signers of such petitions from each of 10 counties, may request the Milk Promotion Board to or the Board of its own volition may hold a referendum to increase the assessment rate provided the rate is not at the maximum assessment rate at the time the request for the increase is made.
     Any referendum to change the assessment shall be considered approved if a majority of those producers voting in the referendum vote in favor thereof.
     The Milk Promotion Board shall require the first purchaser of milk to withhold and remit assessments to the Milk Promotion Board. A first purchaser remitting the assessments for any producer shall deduct the proper amount of assessments from any amount which he owes to such producer. The Milk Promotion Board shall have the power to cause any duly authorized agent or representative to enter upon the premises of any purchaser of milk and examine or cause to be examined by such agent only books, papers and records which deal in any way with respect to the payment of the assessment or enforcement of this Act.