The invasive garden plant it took Aussie couple a decade to eradicate in 'big success'

WA locals Rod and Gaynor Sherwood are one of the state's biggest success stories when it comes to removing the highly toxic arum lily.

WA residents Rod and Gaynor Sherwood show their newly refreshed property.
WA residents Rod and Gaynor Sherwood embarked on a mission to eliminate arum lilies from their 100-acre property. This is the final result. Source: Nature Conservation Margaret River Region

Conservationists have applauded an Australian couple's decade-long battle to eradicate an invasive and highly toxic plant species that infested their 100-acre property.

Western Australian residents Rod and Gaynor Sherwood, from Hamelin Bay in the state's southwest, embarked on a mission to eliminate arum lilies from their sprawling acreage, teaming up with Nature Conservation Margaret River Region to remove all traces of toxic species from their coastal home.

It's a feat that eventually took 10 years. The couple now join more than 2,100 landholders across the region taking part in the "Arum Lily Blitz".

Speaking to Yahoo News Australia, a Department of Primary Industries and Regional Development (DPIRD) spokesperson confirmed arum lilies are indeed a major threat in the state, and urged residents who may unknowingly have the species in their gardens to immediately remove them.

"Arum lily is a declared pest under the Western Australia Biosecurity and Agriculture Management Act 2007," the spokesperson told Yahoo.

"This weed competes with native flora, crops and pastures for water, nutrients and light. It can cause eczema in humans, while stock deaths have occurred from grazing the weed. It is landholders’ responsibility to control arum lilies on their land."

Two split images of arum lilies in Australia - a highly invasive plant species.
While they're often described as 'pretty', these flowers can cause death in both people and animals. Source: WA Department of Primary Industries

For the Sherwoods — one of the state's "biggest success stories" when it comes to the Arum Lily Blitz — removing the plants transformed their acreage from "a once-degraded, coastal cattle grazing property" into "a forested wildlife habitat".

Their land is home to karri, also known as eucalyptus diversicolor, peppermint and bullich forest. The couple said arum lilies once "choked the low-lying drainage basins" and had a presence in loamy open forest areas, affecting about a third of the entire property.

Rod said "spraying in the first year was comprehensive" and "very physical as we covered every square metre of forest". "We enjoyed a 90 per cent kill rate. Then, in the second year we de-headed flowering plants on our place and only sprayed on neighbouring properties," he said.

"From year three onward, we've sprayed our property every two to three years and it's generally taken just two to five-and-a-half days with a single backpack."

The WA local said most areas once suffocated by arums are now back to a state of "high biodiversity".

"Some of those areas were silent when first spraying and now they're rich with birdlife, orchids, reptiles, frogs, quenda and other mammals," Rod said, of his property that had "100 square metre infestations in compacted winter damp areas".

"Overall, we’ve had very good results, improving forest quality and biodiversity,” he said.

Nature Conservation Margaret River Region chair Ann Ward branded the weed as the "cane toad of WA's South West". "It's poisonous to everything — it's a terrible, terrible weed," she told the ABC.

Arum lilies are considered a significant environmental threat in Australia due to their invasive nature. Originally introduced as ornamental plants from South Africa, they have since spread into natural ecosystems, particularly in areas with high rainfall or waterlogged conditions, such as creeks and irrigation channels.

They form dense clumps that outcompete native vegetation, reducing biodiversity and altering local habitats. Their aggressive growth creates monocultures that limit food and habitat availability for many native wildlife species.

In addition to their ecological impact, arum lilies are toxic to humans and livestock if consumed, making them hazardous in agricultural areas. They reproduce both through seeds and tubers, which allows them to spread quickly and makes their control challenging. Effective management strategies include the use of herbicides, mechanical removal, and careful disposal of plant material to prevent further spread.

The plant's invasive nature has led to its classification as a declared pest in regions like Western Australia, where efforts to control it are ongoing, such as the Arum Lily Blitz.

Public awareness and coordinated efforts are crucial to mitigating the impact of arum lilies on Australia's environment and agriculture, experts say.

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