All such assessments shall be paid to the commission by the shipper first shipping such fresh grapes. Every shipper is authorized to collect such assessments from a producer, and shall deduct the assessment from any moneys owed to any such producer. Every shipper shall be primarily and personally liable for the payment of any such assessment, and failure of the shipper to collect the same from any producer shall not exempt any shipper from such primary liability. Any shipper who fails to file a return or pay any assessment within the time required shall thereby forfeit to the commission a penalty of 10 percent of the amount of such assessment determined to be due, but if the commission is satisfied that the delay was excusable, may remit all or any part of such penalty. Such penalty shall be paid to the commission and shall be available for expenditure in the same manner as an assessment.