Any tree or shrub or part thereof growing in the areas designated by this chapter which endangers the life, health, safety or property of the public shall be declared a public nuisance. The owner shall be notified in writing of the existence of the nuisance and given a reasonable time for its correction or removal. If it is not corrected or removed within the time allotted, the Director of Public Service shall cause the nuisance to be corrected or removed and the cost therefor shall be assessed to the owner as provided by law.