Wis. Stat. § 193.401: Board governs cooperative.

A cooperative shall be governed by its board which shall take all action for and on behalf of the cooperative except those actions reserved or granted to members. No director or group of directors may act for or on behalf of the cooperative unless authorized by the board or this chapter. A director may advocate interests of members or member groups to the board, but the fiduciary duty of each director is to represent the best interests of the cooperative and all members collectively.