(9) for any person or labor organization to hinder or prevent by intimidation, force, coercion or sabotage, or by threats thereof, the production, transportation, processing or marketing by a producer, processor or marketing organization, of agricultural products, or to combine or conspire to cause or threaten to cause injury to any processor, producer or marketing organization, whether by withholding labor or other beneficial intercourse, refusing to handle, use or work on particular agricultural products, or by other unlawful means, in order to bring such processor or marketing organization against its will into a concerted plan to coerce or inflict damage upon any producer; provided that nothing in this subsection shall prevent a strike which is called by the employees of such producer, processor or marketing organization for the bona fide purpose of improving their own working conditions or promoting or protecting their own rights of organization, selection of bargaining representative or collective bargaining. The violation of clauses (2), (3), (4), (5), (6), (7), (8) and (9) are hereby declared to be unlawful acts.