A large project to control kahili ginger throughout the West Coast is about to begin. Kahili ginger (Hedychium gardnerianum) was once a widely popular garden plant but is now on a nationwide list of plant banned from sale, distribution and propagation because of its invasive abilities.
Kahili ginger has caused massive problems in northern parts of the country where it has cost hundreds of thousands of dollars to control. A similar pattern of invasion is beginning to emerge on the West Coast, resulting in the plan to get it under control before its impacts escalate.
Tom Belton, DoCs weed ecologist for the West Coast, explains why preventing the spread of ginger is vital to protect the West Coasts natural areas. “In the absence of ginger control, the public could expect to see places like Punakaiki, Charming Creek Walkway, and forest walks around Greymouth and Cobden inundated with ginger over the next few decades” he says. “Now is our chance to stop that happening.”
The main problem areas are around the margins of settlements, where kahili ginger has begun to spread into forested areas, scrub and waste ground. Kahili ginger is spread by roots (rhizomes) and seeds. The roots spread thickly over the ground surface and exclude any other plants or seedlings. Part of the control project will be to encourage homeowners to remove kahili ginger from their gardens. “With the seeds being spread by birds, every kahili ginger plant is potentially a source for reinvasion so it is hoped that the public will support the project by taking responsibility for controlling their ginger” Tom says.
Kahili ginger plants can be difficult to control by digging out, especially where they are large, as any small parts of the roots broken off or left behind will sprout a new plant. Also there arises the problem of what to do with the plant once removed. “Our West Coast towns are littered with sites where garden material has been dumped and discarded plants have gone rampant. Invariably one of the species found is kahili ginger. Garden material must be disposed of responsibly at the approved transfer stations, not over the back fence or down the nearest gully”. Some herbicides will control kahili ginger effectively, and save the backbreaking work of digging it out.
A brochure with information about kahili ginger will be produced and distributed throughout the West Coast during the project. Initial efforts will concentrate on controlling obvious infestations of ginger, and some landowners with large infestations will be approached directly regarding control options. Landowners with concerns about kahili ginger, questions about control methods or those wanting to report infestations should contact their nearest DoC office or the West Coast Regional Council.