7 U.S.C. § 1610
This chapter shall take effect as follows: As to agricultural seeds, and the importation of vegetable seeds, on the one hundred and eightieth day after ; as to vegetable seeds in interstate commerce, one year after ; and as to sections 1591 to 1593 of this title, on .
(Aug. 9, 1939, ch. 615, title IV, § 420, 53 Stat. 1290.)