Subject to approval of the appropriate commodity marketing board, the secretary shall suspend or terminate any marketing program or any provisions of any marketing program whenever the secretary finds that the provisions or program does not tend to effectuate this chapter within the standards and subject to the limitations and restrictions imposed in this chapter. A suspension or termination shall not be effective until the expiration of the current marketing season. If the secretary finds that the termination of any marketing program is requested in writing by more than 33 ⅓ % of the affected producers who produce for market more than 50% of the volume of agricultural commodities produced within the designated production area for market, the secretary shall terminate or suspend for a specified period the marketing program or provisions thereof. The termination shall be effective only if announced on or before the date as may be specified in the program. If 10% of the producers in a commodity group of over 2,000 affected producers or 15% of the producers in a commodity group of less than 2,000 affected producers request in writing that a referendum be held on the question of terminating the program, the secretary must announce and conduct a referendum within a reasonable period of time, and, in any case, within one year of the request, a marketing program shall be terminated if so voted by a majority of those voting.