(a) The provisions of sections 644, 645, and 647 of this title shall not apply:(1) To seed or grain not intended for sowing purposes.(2) To seed in storage in, or being transported or consigned to, a cleaning or processing establishment for cleaning or processing, provided that the invoice or labeling accompanying any shipment of such seed bears the statement "seeds for processing." Any labeling or other representation that may be made with respect to the uncleaned or unprocessed seed shall be subject to section 644 of this title.(3) To any carrier of seed transported or delivered for transportation in the ordinary course of its business as a carrier, provided that such carrier is not engaged in producing, processing, or marketing seeds subject to the provisions of this subchapter.(b) No person shall be subject to the penalties of this subchapter for having sold or offered for sale seeds subject to provisions of this subchapter that were incorrectly labeled or represented as to kind, species, and subspecies; variety; type; or origin, unless the person has failed to obtain an invoice, genuine grower's declaration, or other labeling information or to take such other reasonable precautions to ensure that the identity of the seed is set forth. "Genuine grower's declaration" means a statement signed by the grower that gives for each lot of seed the lot number, kind, variety (if known), origin, weight, year of production, date of shipment, and to whom the shipment was made.