I think your neighbors may qualify as deleterious, unhealthy growths.§ 92.15 CONTROL AND MAINTENANCE OF GRASS ANDWEEDS.
(A) (1) It shall be unlawful for the owner or occupant, or any person having control or management of any lot, area, or parcel of land within the city to permit or allow the presence thereon, or in the unpaved portion of the right-of-way immediately adjacent thereto, ofweeds, grass, brush, or deleterious, unhealthy growths of any species or variety exceeding a height of seven inches above ground level, or any accumulation of deadweeds, grass, or brush, and the same are declared to be a public nuisance.
I guess trees are unlawful as well?