Notwithstanding any other provision of law, no funds heretofore or hereafter authorized to be appropriated to the Department of Agriculture or available under any other than the Act of June 7, 1924 (43 Stat. 653), shall be used for carrying out the programs or activities authorized by sections 564, 565, and 566 1 of this title: Provided, That whenever the programs and activities being carried out under the provisions of sections 564, 565, and 566 1 of this title are inadequate to the needs and purposes of programs and activities authorized by other law the use of funds specifically authorized to be appropriated to the Department of Agriculture or made available under other law shall not be prohibited to the extent that the programs and activities under said sections are inadequate to accomplish the purposes of such other programs or activities.