Lab. Code, § 1153

It shall be an unfair labor practice for an agricultural employer to do any of the following:

(a) To interfere with, restrain, or coerce agricultural employees in the exercise of the rights guaranteed in Section 1152.

(b) To dominate or interfere with the formation or administration of any labor organization or contribute financial or other support to it. However, subject to such rules and regulations as may be made and published by the board pursuant to Section 1144, an agricultural employer shall not be prohibited from permitting agricultural employees to confer with him during working hours without loss of time or pay.

(c) By discrimination in regard to the hiring or tenure of employment, or any term or condition of employment, to encourage or discourage membership in any labor organization.

Nothing in this part, or in any other statute of this state, shall preclude an agricultural employer from making an agreement with a labor organization (not established, maintained, or assisted by any action defined in this section as an unfair labor practice) to require as a condition of employment, membership therein on or after the fifth day following the beginning of such employment, or the effective date of such agreement whichever is later, if such labor organization is the representative of the agricultural employees as provided in Section 1156 in the appropriate collective-bargaining unit covered by such agreement. No employee who has been required to pay dues to a labor organization by virtue of his employment as an agricultural worker during any calendar month, shall be required to pay dues to another labor organization by virtue of similar employment during such month. For purposes of this chapter, membership shall mean the satisfaction of all reasonable terms and conditions uniformly applicable to other members in good standing; provided, that such membership shall not be denied or terminated except in compliance with a constitution or bylaws which afford full and fair rights to speech, assembly, and equal voting and membership privileges for all members, and which contain adequate procedures to assure due process to members and applicants for membership.

(d) To discharge or otherwise discriminate against an agricultural employee because he has filed charges or given testimony under this part.

(e) To refuse to bargain collectively in good faith with labor organizations certified pursuant to the provisions of Chapter 5 (commencing with Section 1156) of this part.

(f) To recognize, bargain with, or sign a collective-bargaining agreement with any labor organization not certified pursuant to the provisions of this part.