(a) During any period in which regulations are in effect pursuant to § 945.42, § 945.52, or § 945.53, or any combination thereof, no handler shall handle potatoes unless such potatoes are inspected by an authorized representative of the Federal-State Inspection Service, and are covered by a valid inspection certificate, except when relieved from such requirements pursuant to recommendations by the committee and approved by the Secretary.

(b) Regrading, resorting, or repacking any lot of potatoes shall invalidate any prior inspection certificates covering such potatoes insofar as the requirements of this section are concerned. During any period in which shipments of potatoes are regulated, as aforesaid, no handler shall handle potatoes after they have been regraded, resorted, repacked, or in any way further prepared for market, unless such potatoes are inspected and covered by a valid inspection certificate as required in paragraph (a) of this section.

(c) Insofar as the requirements of this section are concerned, the length of time for which an inspection certificate shall be valid may be established by the committee with the approval of the Secretary; and such length of time may be different for shipments for different purposes.

(d) When potatoes are inspected in accordance with the requirements of this section, a copy of each inspection certificate issued shall be made available promptly to the committee by the inspection service.