72 Pa. Stat. § 5601
Any person liable to road tax, who shall transplant to the side of the public highway on his own premises any fruit, shade or forest trees, of suitable size, shall be allowed by the supervisor of roads or boards of supervisors of roads, where roads run through or adjoin cultivated fields, in abatement of his road tax, one dollar for every two trees set out; but no row of elms shall be placed nearer than seventy feet; no row of maples or other forest trees nearer than fifty feet, except locust and Carolina poplar, which may be set thirty feet apart, and except fruit trees, which may be set forty feet apart; and no allowance as before mentioned shall be made unless such trees shall have been set out the year previous to the demand for such abatement of tax, and are living and well protected from domestic animals at the time of such demand.
72 P.S. § 5601