77 Pa. Stat. § 463
Any employer employing persons in agricultural labor shall be required to provide workmen's compensation coverage for such employes according to the provisions of this act, if such employer is otherwise covered by the provisions of this act or if during the calendar year such employer pays wages to one employe for agricultural labor totaling one thousand two hundred dollars ($1,200) or more or furnishes employment to one employe in agricultural labor on thirty or more days in any of which events the employer shall be required to provide coverage for all employes. For purposes of this clause, a spouse or a child of the employer under eighteen years of age shall not be deemed an employe unless the services of such spouse or child are engaged by the employer under an express written contract of hire which is filed with the department.
77 P.S. § 463