A ‘pretty’ toxic problem

Parts of Kaiti Hill have at times almost been painted pink with flowering ragwort. Gisborne Herald file picture

A few years back, parts of Kaiti Hill almost looked like they’d been spray-painted pink for spring. While it wasn’t an eyesore, it was unfortunately a pretty serious invasion of a noxious weed — Ragwort.

Also known as holly-leaved senecio, Ragwort is an upright perennial that grows to about one-metre tall. It has waxy, light-green leaves with a course toothed edge.

Between September and November, it has a profusion of pink-purple daisy-like flower heads with yellow centres.

While it’s undeniably pretty in flower, once that’s over a well-developed plant can produce up to 150,000 to 200,000 seeds. About 80 percent of those are viable and are easily spread by wind, livestock, and contaminated machinery.

Ragwort easily re-establishes in a diverse range of environments, but does especially well on coastal dunes and disturbed sites — such as parts of Kaiti Hill were as work got under way to restore it’s native vegetation.

However, the Ragwort invasion of a few years back is no longer an issue and is now under control, Gisborne District Council’s Liveable communities director Michèle Frey says..

“Native restoration plantings now occupy the area once dominated by pink ragwort. However, some roadside plants persist which will be managed in due course,” she said.

Ragwort also has the potential to take over large areas of pastures where it’s particularly problematic because it’s poisonous to stock.

What can be done about this pesky but pretty weed?

According to the council’s online “pest hub”, the plants should be pulled out before they flower — removing the crown. Flowers or seed heads should be burned.

If plants are already in flower when they’re discovered, remove the flower heads, but don’t add them to your compost bin.

Larger infestations can be controlled by using an approved herbicide before the plants flower or by cutting them all off at ground level, removing all the foliage.

Maintaining good pasture cover helps to prevent re-establishment.

Council includes ragwort in its Regional Pest Management Plan among a category of plants listed for a “progressive containment programme”. Under that strategy, the council has committed to taking a leading or partnership role with landowners in progressively controlling ragwort so the impact of it doesn’t get any worse.

The aim is to proactively control pests to zero-density in some parts of the district, or actively contain them in other parts, so they don’t spread further.

Plant species in that category are present in the Gisborne district, but limited in their regional range, the council says.

“Total eradication is not a cost-effective solution to protecting production, social/amenity or environmental values into the future, but preventing the spread limits the effects these pests have on these values.

“GDC believes it is possible to apply the progressive containment rules as a means of ensuring that land that is presently clear of the pest remains so.”

Council’s biosecurity team, which has a modest annual budget of $10,000, has started discretionary hand control of ragwort from Midway Beach south to the Waipaoa River mouth.

It's usually done when wet weather disrupts their work in the rural sector. 

The biosecurity team also carries out direct control of pest plant species that have an eradication status in the pest management plan. For instance, during the past five years one of the team’s focuses has been on monitoring and targeting the eradication pest plant spiny emex at nine sites — seven at Wainui Beach and two at Tolaga Bay/ūawa Blue Waters Motor Camp.

All nine sites are now recorded as non-active and there has been no emergence of new plants to date.

The team also provides ongoing pest plant and animal control to support to Ngāi Tāmanuhiri and Rongowhakaata iwi with native restoration plantings at Te Whero Whero lagoon at Browns Beach, Muriwai.

Council’s liveable communities, which has an annual budget of $112,000, targets pest plants in parks and reserves, including Lysnar Reserve at Wainui Beach, and the town beaches Midway and Waikanae.

The team also works with community groups to restore and maintain dune vegetation around the coast — work that has significantly increased after the destruction caused by storm events in recent years.

Ms Frey says: “The dunes along our Tairāwhiti coast are a natural buffer between the land and the sea. The dune systems offer us protection from rising sea levels and severe weather events. Looking after them is very important.”

“We like to work alongside community groups because they provide the eyes and ears for us as we can’t be everywhere.

“There is an ongoing challenge with a lack of resources to carry out all that needs to be done, so we thank all those hard-working groups who are on this journey with us,” Ms Frey says.