Upon the finding of 11 of the members of the commission that the operation of the provisions of this chapter has not tended to effectuate its declared purposes, the commission may recommend to the director that the operation of this chapter shall be suspended; provided, that any such suspension shall not become effective until the expiration of the marketing season then current. The director shall, upon receipt of such recommendation, or upon a petition being filed with him requesting such suspension, signed by 20 percent of the producers, cause a referendum to be conducted among producers as certified by the commission in accordance with Section 65566, to determine if such operation and the operations of the commission shall be suspended, and shall establish a referendum period, which shall not be less than 10 nor more than 60 days. The director is authorized to prescribe such additional procedure as may be necessary to conduct such referendum.