If, at a public hearing which includes a consideration of the establishment of the boundaries of a proration zone, it appears that the inclusion of territory additional to that which is described in the petition that is being heard is necessary to the proper administration or enforcement of the proposed marketing program, the director shall postpone further proceedings until notice has been given by the director to the producers within the additional territory in the manner which is provided for in Sections 59643, 59644, 59650, 59652, 59653, and 59654. Thereafter, the director may conclude the hearing, and prepare his findings.