Nature Conservation is calling on part-time residents to join its region-wide arum lily control program, offering free herbicide, resources and support for an "all hands on deck" approach.
Project officer Genevieve Hanran-Smith said the region had a large number of absentee landholders and hoped to recruit as many as possible for the Arum Lily Blitz.
"Holiday home owners, semi-retirees and part-time locals love this region for its wonderful forests, coastlines and beaches," she said.
"We have a great number of part-timers already taking part in the Blitz, but we need all hands on deck for the best possible results."
Penny Bower and Grant Johnston split their time between Perth and the Margaret River region, and have been gradually working to eradicate lilies - and other invasive species - since they bought their large Redgate property in 2006.
Mrs Bower said they were seeing "fantastic" results working alongside Nature Conservation, pointing to a four-year period in which the hours of spraying reduced from 10 to seven to three to one.
"There's your money's worth right there," she said.
"The commitment is less each year and being part-time, knowing the contractors can come in and spray at the right time is a big help."
Mr Johnston said it was important neighbours acted together and stressed the affordability of bringing in a contractor.
"It's generally a few hundred dollars a year, not a few thousand, so it's not expensive," he said.
"And it's our responsibility as a landowner - that's the hardline.
"We come down here ... and that's the kind of responsibility we bring."
Arum lilies are an invasive and toxic species introduced from South Africa. They form thick monocultures, choke native vegetation and reduce food availability for native fauna.
When part-time local Linda Falconer bought her property 14 years ago, it was thick with lilies.
Over the years she has worked hard with local Government, community groups and organisations in controlling them.
She has experienced great success, but said it was disappointing when lilies returned; most likely the result of birds dropping seeds from neighbouring properties.
"We have been dismayed to see just how many landowners in Yallingup have not been proactive in the removal of arum lilies from their properties," Mrs Falconer said.
"We live on our property part-time and work hard to keep our wonderfully biodiverse bush block safe from the arum lilies."
The Arum Lily Blitz was launched last year and is bringing together all landholders for a coordinated, concerted and sustained approach.
It is a three-year program backed by funding from the Western Australian Government's State NRM Program.
Ms Hanran-Smith said getting as many absentee landholders on board as possible would be a great win for the program.
"If you only live here part-time but would like to take action, we're here to support you," she said.
"We have information, resources and free herbicide available. Properties in high priority areas with large infestations to deal with may be eligible for contractor subsidies."
For more information and to register, go to natureconservation.org.au