The Department shall inspect at least once each year all nurseries in the State of Illinois as to whether they are infested with insect pests or infected with plant diseases. The Department has authority to collect specimens of plant material in order to make cultures and positive identifications of plant pests. The Department also has authority to inspect nursery stock which is stored in cellars, heeling in grounds or warehouses, to ascertain whether it is infested with insect pests or plant diseases. If, upon the inspection of any nursery, it appears that such nursery and its premises are not infected or infested with insect pests and plant diseases, the Department shall issue to the nursery a certificate of inspection. The certificate of inspection shall be valid until December 31 of the following year. This certificate must be prominently displayed in the main office of the business.
     The provisions of this Section do not apply to florists’ greenhouse plants nor to flowers or cuttings commonly known as greenhouse stock.
     It is unlawful for any person to sell or offer for sale, or to remove or ship from a nursery or other premises, any nursery stock until such stock has been officially inspected and a certificate or permit covering it has been granted by the Department, except that nursery stock may be shipped to the Department without such inspection and certification.