Commodities in liquid form shall be sold only by liquid measure or by weight, and, except as otherwise provided in this act, commodities not in liquid form shall be sold only by weight, by measure of length or area, or by count; provided, that liquid commodities may be sold by weight and commodities not in liquid form may be sold by count only if such methods give accurate information as to the quantity of commodity sold: and provided further, that the provisions of this section shall not apply (1) to commodities when sold for immediate consumption on the premises where sold, (2) to vegetables when sold by the head or bunch, (3) to commodities in containers standardized by a law of this state or by federal law, (4) to commodities in package form when there exists a general consumer usage to express the quality in some other manner, (5) to concrete aggregates, concrete mixtures, and loose solid materials such as earth, soil, gravel, crushed stone, and the like, when sold by cubic measure, or (6) to unprocessed vegetable and animal fertilizer when sold by cubic measure. The director may issue such reasonable regulations as are necessary to assure that amounts of commodity sold are determined in accordance with good commercial practice and are so determined and represented as to be accurate and informative to all parties at interest.