The commissioner of agriculture is hereby empowered to establish temporary chemical laboratories in fruit growing sections during the harvesting and shipping season for the purpose of examining fruit and determining the amount of poisonous spray residue thereon, and in the case of lots of fruit prepared for shipment to collect representative samples from such lots; to cause to be made chemical analyses for poisonous spray residue remaining on the fruit and in the event, as the result of such examination on representative samples, that prohibited poisonous spray residue does not exceed the maximum tolerance allowed therefor by the secretary of agriculture of the United States; to cause to be issued a certificate stating that fact. Certificates issued will be and are applicable only to such designated lots as have been appropriately numbered and identified. The owner of such lot of fruit shall pay such reasonable fees for the examination and issuance of certificate as is determined by the commissioner of agriculture.