Within the 60-day period immediately preceding the effective date of an order issued under section 6103(b) of this title, the Secretary shall conduct a referendum among mushroom producers and importers to ascertain whether the order shall go into effect.

The order shall become effective, as provided in section 6103(b) of this title, if the Secretary determines that the order has been approved by a majority of the producers and importers voting in the referendum, which majority, on average, annually produces and imports into the United States more than 50 percent of the mushrooms annually produced and imported by all those voting in the referendum.