SCARBOROUGH – A contentious vote of the Scarborough Town Council Wednesday to adopt a new “integrated pest management” policy has been invalidated, resetting the status quo to a similar policy adopted last fall, which requires the use of organic pesticides.

In September, the council voted 4-1 to adopt a policy championed by the advocacy group Citizens for a Green Scarborough. It banned the use of synthetic pesticides on town property without a waiver issued by a newly created pest control advisory committee or an “emergency” application approved by the town manager. A new version, presented Wednesday by Councilor Richard Sullivan, encouraged but did not require use of organic pesticides.

Members of the citizens group turned out in force at Wednesday’s meeting, arguing that the new policy threatened to turn back the clock and clear the way for use of potentially toxic chemicals in town.

Despite that outcry, Sullivan’s version appeared to pass 3-0, prompting Councilor Karen D’Andrea to walk out of the meeting. She and Carol Rancourt abstained from the vote because, they said, Sullivan’s version amounted to reconsideration of the existing policy. Although Sullivan argued his right to present a new policy to a new board constituted after the November election, D’Andrea and Rancourt said that, because he had weighed in against the existing policy, Sullivan could not under council rules present a do-over until one year after that vote.

Meanwhile, Sullivan recused himself from voting when D’Andrea and Rancourt claimed he had a conflict of interest, because his brother has a $40,000 lawn mowing contract with the town.

With Council Chairman Ron Ahlquist absent, Sullivan’s new pest control policy appeared to pass with support from councilors Judy Roy, Jessica Holbrook and Richard Benedict.

However, in a Thursday afternoon email, Town Manager Tom Hall pointed out that Scarborough’s Town Council Policy Manual requires a majority of all members to adopt new measures, not merely those present and voting. Because there were not four affirmative votes, he said, the new policy did not pass.

“I have to view the existing policy [adopted in September] to be still in effect and will act accordingly unless directed otherwise,” said Hall, on Friday.