In determining whether this chapter is approved by producers, the director must find that at least 40 percent of the total number of producers from the list established by the director participated in the referendum, and that either one of the following has occurred:
(a) Sixty-five percent or more of the producers who voted in the referendum voted in favor of this chapter, and the producers so voting marketed a majority of the volume of winegrapes in the preceding marketing season, or in the current marketing season if the harvest is completed prior to the vote, by all the producers who voted in the referendum.
(b) A majority of the producers who voted in the referendum voted in favor of this chapter, and the producers so voting marketed 65 percent or more of the volume of winegrapes in the preceding marketing season, or in the current marketing season if the harvest is completed prior to the vote, by all the producers who voted in the referendum.