A producer member of each commodity board must be a practical producer of the affected commodity and must be a citizen, resident of this state, and over the age of eighteen years. Each producer board member must be and have been actually engaged in producing such a commodity within the state of Washington for a period of five years and have, during that period, derived a substantial portion of his or her income therefrom and not be engaged in business, directly or indirectly, as a handler or other dealer. A handler member of each board must be a practical handler of the affected commodity and must be a citizen, resident of this state, and over the age of eighteen years. Each handler board member must be and have been, either individually or as an officer or employee of a corporation, firm, partnership, association, or cooperative, actually engaged in handling such a commodity within the state of Washington for a period of five years and have, during that period, derived a substantial portion of his or her income therefrom. The qualification of a member of the board as set forth in this section must continue during the term of office.