PORTLAND, Maine — Maine’s largest city has approved an ordinance that bans the use of synthetic pesticides on most public and private property.

The Portland City Council unanimously approved the ordinance Wednesday night. The new rules are set to go into effect July 1.

The Portland Press Herald reports a handful of properties that would be exempt from the ordinance, including Hadlock Field, home of the Portland Sea Dogs minor league baseball team. A golf course and five high-use athletic fields are also exempt.

Portland’s ordinance is based on a law in neighboring South Portland. The city’s Sustainability and Transportation Committee voted to recommend creation of the ordinance in October. The ordinance sparked debate among those who favor organic lawn care and those who fear it would make it harder to control disease-carrying insects such as mosquitoes.