Source: Department of Conservation
Date: 11 March 2025
The invasive plant Cuscuta campestris – also known as “golden dodder”, and more commonly referred to as simply “cuscuta” – was previously only known to be in north Waikato. That was until it was identified near the Piako River in 2024, on a stretch of the Kopuatai peat dome in DOC’s Hauraki operations district.
Cuscuta is a parasitic plant that sucks nutrients from other plants, and has the potential to smother native plant species. It can grow on a wide variety of plants, including pasture crops and waterfowl food, compromising both recreational and biodiversity values wherever it is found.
Biodiversity Ranger Rachel Langman says C. campestris was discovered by DOC staff at Kopuatai while doing routine trap checks. They called on colleagues from DOC’s Waikato district for initial support in how to address the infestation.
“Kopuatai is a Ramsar site and an important habitat for threatened native species like matuku-hūrepo/bittern, mātātā/fern birds, and native fish,” says Rachel.
“Cuscuta presents a real threat to those species if left unchecked. New Zealand’s native species are unique and special, and most are only found here. Once they’re gone, they’re gone forever.”
To address the Kopuatai infestation, staff from DOC and Waikato Regional Council collaborated on a plan, which saw a large digger rolled out onto the site in January.
The digger’s role was to remove the top 10cm of soil – containing cuscuta seed – and burying that soil in a 1m deep hole so the seeds couldn’t germinate. This will prevent the weed from growing or being spread to other areas through human activity.
“Although the digger method seems drastic, it was identified as the best approach to controlling the infestation before it became unmanageable,” says Rachel.
“We expect grasses, which are not a host of cuscuta, to regenerate where the topsoil has been removed.”
“Our team will continue to monitor the area regularly to prevent the reinfestation of this plant pest.”
If anyone sees cuscuta on land managed by DOC, they should call 0800 DOC HOT and, if possible, provide the exact location so rangers can investigate.
Aotearoa New Zealand has more threatened species than anywhere else in the world, with over 4000 species considered threatened or at risk of extinction. It is vital we all work together to bring nature back from the brink, by removing pests and restoring ecosystems to create safe havens for native wildlife.
Background information
Cuscuta campestris seeds can be spread by seed and plant fragments being moved by water, vehicles, equipment, clothing or animals – hence the work alongside the river. Seeds can also survive the digestive tracts of birds and animals.
If left unmanaged, cuscuta can grow up to five metres in two months, smothering surrounding plants.
One cuscuta plant can produce up to 16,000 seeds. Infestations can spread to surrounding areas including other wetlands and farmland, where it can reduce the food source for ducks, lower crop production and has found to be potentially toxic to cattle.
The Convention on Wetlands was adopted in the Iranian city of Ramsar in 1971 and came into force in 1975. Kopuatai Wetland is one of seven Ramsar sites in New Zealand. The largest unaltered raised bog in New Zealand, it is surrounded by mineralized swampland and associated lagoons.
Contact
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