The provisions of section 6101 of title 41 shall not apply to any purchase by the Forest Service of forest-tree seed or cones or of forage plant seed when the amount involved does not exceed $10,000, nor to any purchase of forest-tree nursery stock when the amount involved does not exceed $500, whenever, in the discretion of the Secretary of Agriculture, such method is in the public interest.

(June 30, 1914, ch. 131, 38 Stat. 429; Apr. 24, 1950, ch. 97, § 2, 64 Stat. 83.)