29 USC 1832 - Wages, supplies, and other working arrangements

(a) Payment of wages 
Each farm labor contractor, agricultural employer, and agricultural association which employs any seasonal agricultural worker shall pay the wages owed to such worker when due.
(b) Purchase of goods or services by worker 
No farm labor contractor, agricultural employer, or agricultural association shall require any seasonal agricultural worker to purchase any goods or services solely from such farm labor contractor, agricultural employer, or agricultural association.
(c) Violation of terms of working arrangement 
No farm labor contractor, agricultural employer, or agricultural association shall, without justification, violate the terms of any working arrangement made by that contractor, employer, or association with any seasonal agricultural worker.