Except as otherwise provided in Sections 6502, 6504, 6505, 6506, and 6924, it is unlawful for any person to sell, deliver, or transport any nursery stock from one county to another county within the state unless he has affixed to such nursery stock in a conspicuous place one of the following which is issued by the commissioner of the county of origin:
Ca. Food and Agric. Code § 6922