Madagascar ragwort

What is Madagascar ragwort?

Madagascar ragwort is an extremely toxic weed that can cause severe, irreversible liver damage in cattle, often leading to death. Its appearance is very similar to gravel groundsel (Senecio skirrhodon), making it difficult to identify.

Madagascar ragwort can rapidly spread once it’s established - it can germinate year-round and individual plants can produce 10,000 seeds in a 6-week germination window. It can be spread by wind, hay/baleage contamination, stock movements and machinery/vehicles.

Reports of up to a 35% reduction in pasture capacity have been seen on one Northland sheep and beef property. Some dairy farms could be affected in the same way. Read more in this Rangiputa Farm case study.

Madagascar ragwort is difficult to control. The lifecycle and invasiveness of the plant, limited herbicide options, and a lack of alternative control methods can make the management of large-scale outbreaks extremely challenging and costly.

Where is it found?

Madagascar ragwort is established in parts of Northland and has recently been confirmed in South Wairarapa. Its wider distribution may change as surveillance continues.

For the most up-to-date information on known distribution and regional pest management status, use MPI’s New Zealand Established Pests Portal.

Control methods

• The best method of control is prevention. Learning how to identify it early and stop outbreaks before they become large-scale is important.
• Small-scale control can be done by hand-pulling and placing in a sealed bag. Care should be taken not to spread seeds and disturb the soil surrounding the plants.
• Intensive herbicide control is necessary for large-scale outbreaks. The end-goal is often to manage it, rather than eradicate it.
• AgResearch has completed a report with options for the control of Madagascar ragwort.

What is DairyNZ doing?

DairyNZ has signed a Memorandum of Understanding (MOU) with Northland Regional Council, Beef + Lamb New Zealand, and Pāmu committing to work together toward solutions. The group have initially agreed to fund a report into economic impacts and options for management, which will be presented to parliament. We will continue to update you on this progress.

More information

For more information on identification, control and management options, see Northland Regional Council’s information on Madagascar ragwort.