It is an unfair labor practice for an employer:
(1) To interfere with, restrain, or coerce symphony musicians in the exercise of their rights guaranteed by this chapter;
(2) To control, dominate, or interfere with a bargaining representative;
(3) To discriminate against a symphony musician who has filed an unfair labor practice charge or who has given testimony under this chapter;
(4) To refuse to engage in collective bargaining.