The forum's founders - from Calderdale, Wakefield and Doncaster Councils - are planning a conference in York in January entitled Future Use of Pesticides: The Way Forward.
Founder member Mark Dempsey said the introduction of the Sustainable Use Directive meant there was more reason for local authorities to get involved: "It is about opening doors and talking to each other. Sharing ideas is important."
The forum has increased to 16 local authorities and Dempsey hopes it will rise to 20 by January.
Funding for the forum is being shared out on a rolling basis, with one local authority contributing £500 a year. "The bigger commitment is the time," said Dempsey.
The forum has already paid off for Calderdale, after Doncaster Council staff carried out hand-arm vibration testing for Calderdale at a fraction of the quoted price.
The group also hopes to organise a regional practical competition that will showcase skills.