This chapter, except as necessary to conduct an implementation referendum vote, shall not become operative until the secretary finds in a referendum vote conducted by the secretary that at least 40 percent of the total number of producers from the list established by the secretary pursuant to this article participate, and that a majority of the producers voting in the referendum voted in favor of this chapter, and the producers so voting handled a majority of the total quantity of walnuts handled in the preceding marketing year by all those producers who voted in the referendum.