Each commissioner, subject to direction and control by the county board of supervisors, shall supervise the control and destruction of all noxious weeds in the county, including those growing within the limits of cities, within the confines of abandoned cemeteries, and along streets and highways unless otherwise provided. A commissioner shall notify the department of public safety of the location of marijuana plants found growing on public or private property. A commissioner may enter upon any land in the county at any time for the performance of the commissioner’s duties, and shall hire the labor and equipment necessary subject to the approval of the board of supervisors.