7 C.F.R. § 1214.81
(a) Required referendum. For the purpose of ascertaining whether the persons subject to this Order favor the amendment, continuation, suspension, amendment, or termination of this Order, the Secretary shall conduct a referendum among persons subject to assessments under § 1214.52 who, during a representative period determined by the Secretary, have engaged in the production or importation of Christmas trees:
(2) The order will be approved in a referendum if:
(b) Subsequent referenda. The Secretary shall conduct subsequent referenda: