41 USC 6b - Miscellaneous exceptions from advertisement requirements

(a) Control of insects, pests, and grass diseases 
Materials and equipment for the control of incipient or emergency outbreaks of insects, pests, or grass diseases, including grasshoppers, Mormon crickets, and chinch bugs, may be procured with any sums appropriated to carry out the provisions of sections 148 to 148e1 of title 7 without regard to the provisions of section 5 of this title, and the transportation thereof may be under such conditions and means as shall be determined by the Secretary of Agriculture to be most advantageous.
(b) Omitted 
(c) Operations on Menominee Indian Reservation 
All contracts for labor or supplies necessary for the carrying on of operations on the Menominee Indian Reservation pursuant to the Act of March 28, 1908 (35 Stat. 51), as amended, shall be exempt from the requirements of section 5 of this title.
(d) Sale of Indian produced forest products 
The lumber and other forest products produced by Indian enterprises from the forests on Indian reservations may be sold under such regulations as the Secretary of the Interior may prescribe, without compliance with section 5 of this title.
[1] See References in Text note below.