No claim may be made as against the seller of agricultural products by a dealer or cash buyer under this chapter, and no credit may be allowed to such dealer or cash buyer as against a consignor of agricultural products by reason of damage to, or loss, dumping, or disposal of agricultural products sold to said dealer or cash buyer, in any payment, accounting or settlement made by said dealer or cash buyer to said consignor, unless said dealer or cash buyer has secured and is in possession of a certificate, issued by an agricultural inspector, county health officer, director, a duly authorized officer of the state department of social and health services, or by some other official now or hereafter authorized by law, to the effect that the agricultural products involved have been damaged, dumped, destroyed or otherwise disposed of as unfit for the purpose intended. Such certificate will not be valid as proof of proper claim, credit or offset unless issued within twenty-four hours, or a reasonable time as prescribed by the director, of the receipt by the dealer or cash buyer of the agricultural products involved.