Ragwort

(Senecio jacobaea)

Boundary Control Pest

A small clup of green stalks and big yellow flowers.

Ragwort is an erect biennial or perennial herb that reproduces from crowns, roots and seeds. It commonly grows to a height of between 45 and 60 centimetres. Ragwort is characterised by its conspicuous yellow flowers during summer. The majority of plants flower in their second season from December to March. The seeds are principally wind-dispersed, with most seed falling close to the parent plant, although water and animals may also play a role. Dispersal may also occur in hay, farm implements or uncertified seed.

Reasons for the Strategy

Ragwort is a serious pasture weed. It leads to reduced pasture production, creating ongoing associated costs of control. Cattle tend to avoid both the plant and the pasture close to the plant, further exacerbating its smothering effect, reducing pasture utilisation. The plant is toxic to cattle, and, to a lesser extent, sheep.

Ragwort is assessed at “7” on the infestation curve. It is widespread throughout the Tasman-Nelson region. The distribution of Ragwort has reached a level where the most cost-effective form of control is to require boundary control, and to invest in biocontrol. This will assist in protecting land that is clear, or being cleared of Ragwort, from invasion from adjacent land by Ragwort. Extensive areas of suitable habitat, and the potential for it to cause significant adverse effects, mean the benefits of boundary control far outweigh the costs.

Biocontrol agents for Ragwort that have been released during the last decade have been highly effective in reducing its density on different sites, but there are still opportunities for further distribution. No complaints have been received during the term of the last Strategy, but it is still considered to be a serious pest of pastoral land. For these reasons, it will continue to be a Boundary Control Pest in the Strategy, ensuring that the Management Agency can continue to distribute the biocontrol agents.

Objective

To control the spread of Ragwort from adjacent properties to land that is clear, or being cleared of Ragwort, in the Tasman- Nelson region during the term of the Strategy.

Alternative Measures

The alternative option of “do nothing” or relying on voluntary control will not achieve the objective of the prevention of the spread of Ragwort to adjacent properties where there is no Ragwort, or where control is being carried out. Requiring a greater level of control, instead of just boundary control, is not appropriate given the widespread distribution of Ragwort, and that the occupier is the main beneficiary.

Strategy Rule for Ragwort

The occupier shall destroy all adult and juvenile forms of Ragwort located up to 20 metres from the boundary of the land that they occupy where the adjacent property is clear, or being cleared of Ragwort. A breach of Strategy Rule 7.8.5 is an offence under Section 154(r) of the Biosecurity Act 1993.

Explanation of Strategy Rule

The Management Agency will limit its intervention to enforce compliance of the rule to occasions when a reasonable complaint is received from an adjoining land occupier. This would require the complainant’s land to be already clear, or being cleared of Ragwort, and that any invasion of the pest plant through the boundary has the potential to cause economic harm to the complainant’s land.

Biosecurity Act Requirement

No person shall knowingly sell, propagate, breed, release, or commercially display Ragwort, under Sections 52 and 53 of the Act.