Arum Lily (Zantedeschia aethiopica)

Arum Lily: A Beautiful Flower, a Serious Declared Pest!

Recognise it. Manage it. Help protect our region.

Arum Lily (Zantedeschia aethiopica), a robust, dark green, succulent herb, also known as Calla Lily, may be recognised for its distinctive white flowers and lush green foliage, but behind its attractive appearance is a highly invasive declared pest plant that poses a significant threat to our region’s natural environment, biodiversity and agricultural productivity.

Originally introduced to Western Australia from South Africa as a garden plant, Arum Lily has spread into our bushlands, waterways, wetlands and agricultural areas, where it can form extensive, dense infestations that are difficult to control.

This plant prefers sub-tropical to temperate climates and is tolerant to frost.  It thrives in areas with a high-water table and can tolerate water logging for short periods of time.  It is found in creeks, irrigation ditches and areas of summer-moist land in the higher rainfall South West, often forming large dense clumps. Arum lily spreads by regeneration from tuber fragments and by seed. The white cone-shaped flowers bloom in spring. This plant is toxic to both humans and livestock eaten.

Arum Lily is a priority declared pest for management within Leschenault Biosecurity Group’s (LBG) Operational Area.

Why Does Arum Lily Matter?

Arum Lily is much more than an unwanted garden escapee. It is a declared pest in Western Australia and designated as a priority for management within the Leschenault Biosecurity Group’s Operational Area. Once established, it can spread aggressively outcompeting and displacing native vegetation and significantly altering natural habitats.

• Highly Invasive: Establishes quickly and spreads aggressively through seeds and underground tubers, forming dense infestations that can rapidly overtake surrounding vegetation.
• Threat to Native Biodiversity: Outcompetes native plants, reducing vegetation diversity and the food and habitat available to native wildlife.
• Reduced Agricultural Productivity: Invades grazing land, reducing available pasture and limiting productive land use.
• Toxic to Humans and Animals: All parts of the plant are poisonous if ingested, posing a risk to people, livestock and pets.
• Persistent and Difficult to Control: Can regenerate from underground tubers and seeds remaining in the soil, requiring ongoing management to prevent regrowth and reinfestation.

Left unmanaged, small infestations can become major problems. Early action and ongoing follow-up make a significant difference.

Taking Action: Effective Arum Lily Control

Effective control takes the right approach, good timing and persistence.
Arum Lily can be controlled using a combination of methods, with targeted herbicide application generally the most practical and effective option for established infestations.

Herbicide Control  

Foliar spraying with an appropriately registered herbicide is generally recommended for managing Arum Lily infestations.
Always follow the applicable herbicide product label and take particular care when working near waterways, wetlands and other environmentally sensitive areas.

Timing Matters! In our region, Arum Lily control is generally undertaken from winter through spring, often between July and November. The most suitable application period depends on the herbicide selected, the plant’s growth stage and seasonal conditions.

Two commonly used herbicide control approaches include:

Chlorsulfuron – LBG recommends use of Chlorsufuron as a preferred control for Arum Lily: Chlorsulfuron is a slow-acting, selective herbicide that has proven effective in controlling Arum Lily when applied correctly and at the appropriate time. It is absorbed through the plant’s leaves and roots, targeting its growth processes and helping to control the underground tubers from which Arum Lilies can regrow. This broadleaf selective herbicide controls Arum Lily without killing surrounding grasses, making it particularly useful where maintaining groundcover is important. However, it can also affect other desirable plants, so careful, targeted application is essential. LBG promotes the responsible use of chlorsulfuron as part of an ongoing approach to Arum Lily management. Applications are generally undertaken during the active growing and flowering period, with timing influenced by seasonal conditions and plant development.

Metsulfuron and Glyphosate: Another effective chemical treatment is use of a mixture of metsulfuron and glyphosate, however this should be done before flowering to avoid the potential for seed drop and return of infestations. When spraying with a glyphosate mixture, be sure to only spray intended plants to avoid harm to off-target native plants.

Physical Removal    

Manual removal may be practical for small, isolated infestations. However, the entire underground tuber system must be removed to minimise regrowth. rum Lily can spread by seed and by roots, so when controlling by physical removal, you must ensure all root fragments are removed from the ground to prevent regrowth.Care must also be taken to prevent the spread of seeds or tuber fragments through soil disturbance, equipment movement or inappropriate disposal of plant material.

Persistence is Key  

Persistence with follow-up each year to control regrowth is required until eradication is achieved on your property.  One treatment is rarely enough to eliminate an established Arum Lily infestation. Even after successful initial control, underground tubers and seeds remaining in the soil can produce new plants. Inspect treated areas regularly, control emerging plants and continue follow-up management over successive seasons. A consistent, long-term approach is essential to reducing infestations and preventing their return.

Contact LBG to discuss Arum Lily control needs for your property.

Every property is different. Our team can help you consider practical control options suited to your circumstances.
Contact us by email: info@lbginc.org.au or ring us on 0477 049 967.

Read more about Arum Lily at:  weeds.org.au/profiles/arum-lily-calla