The department, through its agents, shall, at least once each year, inspect all nurseries and other places in which nursery stock is stored, kept or offered for sale. It shall also have the authority to inspect or reinspect, at any time or place, any nursery stock shipped or moved in or into this Commonwealth. In addition to inspection, the department may collect samples for testing to detect plant pests. A nursery shall furnish the inspector, on request, a list of any or all sources from which nursery stock was obtained. No nursery stock shall be removed, transported, sold or offered for sale which has not been inspected and approved by an agent of the department. Following the inspection, a report of inspection will be issued.