(1) The commission may change the method or the amount of the assessment imposed in section 12, or both, by complying with this section.

  (2) If the commission proposes a change as described in subsection (1), then it shall conduct a referendum of growers relative to any such change.

  (3) After a referendum, the commission shall implement a proposed change if more than 50% of the growers voting approve any proposed change and those voters represent more than 50% of the hundredweight voting.