Iowa Code § 317.12: Weeds on railroad or public lands and gravel pits.

All noxious weeds on railroad lands, public lands and within incorporated cities shall be treated in such manner, approved by the board of supervisors, as shall prevent seed production and either destroy or prevent the spread of noxious weeds to adjoining lands. Gravel pits infested with noxious weeds shall not be used as sources of gravel for public highways without previous treatment approved by board of supervisors.