Each person whose name appears on the label as handling agricultural, vegetable, flower, or tree and shrub seeds subject to this subdivision shall keep for a period of at least 2 years complete records of each lot of agricultural, vegetable, flower, or tree and shrub seed handled and shall keep for at least one year a file sample of each lot of seed after final disposition of such lot. All such records and samples pertaining to the shipment or shipments involved shall be accessible for inspection by the commissioner or his agent during customary business hours.