Whenever the season average price to producers for prunes is below the parity level specified in section 2(1) of the act, no handler shall ship consumer packages of prunes unless such prunes are packed and labeled in accordance with the specifications prescribed in this subpart; and whether prices are above or below parity, no handler shall use the nomenclature designations in §993.515(b) to describe size categories other than those prescribed pursuant to §993.515(c).