Moth plant marching orders

The Leigh Coast Community Care group has been commended for its work in raising awareness of moth plant and assisting people to get rid of it.

Landholders may soon have another weapon in their arsenal to help control moth plant weed (Araujia hortorum).
The Environmental Protection Authority (EPA) has approved an application by Northland Regional Council to release the moth plant rust fungus Puccinia araujiae.

The rust fungus is a highly specific parasitic fungus that is expected to severely impact on moth plant, its primary host. The typical symptom of the fungus is rust-coloured lesions on the plant leaves and fruit, causing defoliation and killing the plant’s stems. The fungus will also limit seed production.

The EPA’s general manager application and assessment Sarah Gardner says the manual control of the moth plant weed is time consuming and has only had limited success.

“Reductions in the abundance of moth plant populations may also deliver biodiversity and conservation outcomes,” she says.

“Moth plant belongs to the sub-tribe Oxypetalinae. Other members of this sub-tribe, including the exotic ornamental tweedia (Oxypetalum caeruleum), will possibly be affected by the fungus.

“If necessary, home gardeners could mitigate damage to tweedia by applying an over-the-counter fungicide. There are no native species that belong to the same sub-tribe or tribe as moth plant therefore no native plants are expected to be harmed by the fungus.”

Moth plant was introduced into New Zealand as an ornamental species during the 1880s.

It is a tough perennial, broad-leaved herbaceous climber with twining stems, clusters of small cream tubular flowers and choko-like fruit. It can reach over five metres when it grows up trees or creeps over the ground, shading out low-growing vegetation. The sap of the fruit and stem is a skin irritant. The weed is considered a threat and cannot be sold, propagated or distributed in New Zealand. Some regional councils require landowners or occupiers to remove moth plant from their property.

It is widespread in Northland and Auckland, and found throughout the Coromandel, Waikato and Bay of Plenty. The rust fungus is the second biological control agent approved for release under the HSNO Act to control moth plant. The first agent, the beetle Colaspis argentinensis, was approved in 2011 but has not yet been released. If the beetle is released, the two agents are expected to work together to suppress the moth plant.