Producer assessments shall be upon the producer. The first shipper or processor of strawberries being assessed shall deduct the assessment from amounts paid by him or her to the producer, and shall be a trustee of the funds until they are paid to the commission at the time and in the manner prescribed by the commission. A producer who delivers or markets strawberries to persons other than to a shipper or processor shall pay an assessment directly to the commission at the time and in the manner prescribed by the commission.