It shall be unlawful for any owner of any lot or parcel of land in the city to permit
or maintain on any such lot or parcel of land any ash, elm or parts of which, as provided
in section 78-61(a) and (b), is a public nuisance, and it shall be the duty of any such owner to promptly
remove and properly dispose of any such trees, and parts thereof, under the supervision
and direction of the city manager or his duly authorized representative.