There is hereby levied on all commercial tree fruit produced in this state or held out as being produced in this state for fresh or processing use, an assessment, initially not to exceed ten cents per ton on all such tree fruits, except that such assessment for apples for fresh shipment shall be at the rate of one-half cent per one hundred pounds gross billing weight. Such assessment on all such commercial tree fruit shall not become effective until approved by a majority of such commercial producers of tree fruit voting in a referendum conducted jointly by the Washington apple commission, Washington state fruit commission, and the department. The respective commissions shall supply all known producers of tree fruits subject to their respective commissions with a ballot for the referendum and the department shall supply all known tree fruit producers not subject to either of the commissions with a ballot wherein all known producers may approve or disapprove such assessment. The commission may waive the payment of assessments by any class of producers of minimal amounts of tree fruit when the commission determines subsequent to a hearing that the cost of collecting and keeping records of such assessments is disproportionate to the return to the commission.