Ragwort: declared pest

Page last updated: Monday, 20 July 2020 - 3:14pm

Ragwort, stinking willie, St James wort, tansy ragwort (Senecio jacobaea) is a declared pest in Western Australia (WA). This article describes the nature of the plant with links to requirements land owners/occupiers must adhere to, pest control methods and how to search, detect and report it.

Form: herbaceous — perennial

Status: present in WA

Orignating in Europe, Ragwort is a major pasture weed in New Zealand, Tasmania and Victoria. In WA it is currently confined to one property, but pastures in the high rainfall districts (more than 750 millimetres) are at risk from this weed.

Appearance

Ragwort is normally a biennial or perennial upright plant 0.6-1 metres tall.

Stems: each plant has numerous separate stems; each rigid branched stem is greenish-purple in colour.

Leaves: deeply lobed, ragged in appearance, dark green on top and lighter underneath.

Flowers: daisy-like, in bright yellow heads about one centimetre across. Flowers from October to March.

Seeds: light brown, about two millimetres long by 0.5 millimetres in diameter and attached to a pappus of feathery hairs. Most seeds germinate almost immediately, but some may remain viable in the soil for many years.

Mature plants have a crown just beneath the soil surface, from which numerous fleshy roots are produced. Ragwort reproduces from seed, from root fragments and from the crown of the plant, which persists from season to season.

Online weed identification training

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Agricultural and economic impact

Ragwort competes strongly with more desirable pasture species and can be a very difficult plant to control. Ragwort is poisonous to stock, especially cattle and horses, but animals generally avoid it unless they are hungry. Cows forced to eat ragwort produce tainted milk.

Declared pest category

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for ragwort in the WAOL using the scientific name Senecio jacobaea.

Requirements for land owners/occupiers and other persons

Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.

Search > detect > report

MyPestGuide™ Reporter
via app or online
(Select 'Send report to MyWeedWatcher' from menu)
mypestguide.agric.wa.gov.au

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
padis@dpird.wa.gov.au

Detectability: hard to find. Mature ragwort plants are quite distinct with their abundance of yellow flowers but could easily be confused with other yellow daisy-flowered species, including native Senecio species and Dittrichia viscosa.

Who should look for it: there is currently only one known infestation near Walpole; owners/managers of the known affected property, adjacent properties and any properties that have links with the affected property should be aware of this weed.

When to find it: ragwort is most likely to be found at flowering, which is from December to March, plants can take several years before they flower.

Where to find it: humid temperate regions with annual rainfall greater than 750 millimetres.

Control method

Control methods for this declared plant can be found through the ragwort control link.

Management calendarTable displays: Search Dec-Mar. Germination Sep-Apr. Actively growing Jun-Mar. Flowering Dec-Mar. Fruiting: Jan-Apr. Treatment Jun-Nov. Manual removal to a depth of 200mm: Sep-Jan

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
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