The board at regular intervals, but not less than twice per year, shall convene a formal meeting at which the board shall review its current annual marketing plan and its proposed annual marketing plan for the succeeding 1-year period. Once a year at these formal meetings, the board shall review and either approve or reject the proposed annual marketing plan. Subject to section 7b, an approved annual marketing plan shall be instituted by the bureau. A rejected marketing plan shall not be instituted by the bureau.