The Washington apple commission and Washington state fruit commission in order to avoid unnecessary duplication of costs and efforts in collecting assessments for tree fruits at the time said commissions collect assessments due under the provisions of their acts may also collect the assessment due the commission on such tree fruit. Such assessments on winter pears may be collected by the Washington state fruit commission or in a manner prescribed by the commission. Assessments collected for the commission by the Washington apple commission and the Washington state fruit commission shall be forwarded to the commissions expeditiously. No fee shall be charged the commission for the collection of assessments because the research conducted by the commission shall be of direct benefit to all commercial growers of tree fruits in the state of Washington. However, the commission shall reimburse at actual cost to the department or the Washington state fruit commission or apple commission any assessment collected for the commission by such agencies for any tree fruit subject to the provisions of this chapter, but not subject to pay assessments to the Washington state fruit commission or the Washington apple commission.