Growth Habit: Ragwort, in its first year, appears as a flat rosette of deep green wavy leaves. The bases of these leaves are typically purplish in colour. At the flowering stage, the leaves of the rosette die off to be replaced by an upright bush with deeply lobed leaves. The bush can grow from .5m to 2m in height depending on growing conditions.
Type of Plant: Herbaceous biennial. Plants usually flower in their second year and then die. Control methods that damage the plant, but do not kill it, tend to encourage the plant to become a perennial which will flower in successive years.
Fruit/Seed: Small seeds are attached to a feathery pappus.
Dispersal: The small seeds can be dispersed as contaminants on animal coats, in soil on vehicles and machinery and in hay. Although the pappus attached to the seed can allow the seed to be blown up to a kilometre or more, most wind dispersed seed falls within 20 metres of the parent plant. The seeds are often carried by water along drainage lines.
Distribution: Ragwort is widely distributed throughout the grazing areas of Tasmania, although its spread in some areas seems to have been limited by low rain fall and sheep grazing.
Status: Ragwort is a Declared Weed under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of Ragwort are prohibited in Tasmania. Where possible land holders must eliminate infestations. In areas where this is not practicable, land holders have a responsibility to contain and reduce infestations.
- Ragwort causes significant loss of pasture production. Once established it is extremely competitive with pasture species. When plants die off after flowering they leave bare patches that can be colonised by other weeds.
- Ragwort is poisonous to all types of stock although older sheep and some breeds of sheep are less affected. Most grazing animals avoid eating the plant unless there is a shortage of green feed. However, dead and dried Ragwort plants are very attractive to cattle and horses and poisoning can occur when it contaminates hay or silage. Single animals may become addicted to Ragwort and search it out resulting in poisoning and death.
There are a few similar plants with yellow flowers that flower at the same time as Ragwort. Native Fireweeds and Groundsels, most commonly Senecio linearifolius, occur in the region. They differ by having smaller yellow flowers and having longer strap like leaves.
St John’s Wort (Hypericum perforatum), also a pasture weed, along with bushland and roadsides, is commonly mistaken for Ragwort. As it is also a weed, removal of this plan is also a good idea.
- Grazing (May – Dec). Sheep can be used to graze and suppress Ragwort; however the plant is toxic and sheep should not graze for more than two seasons on ragwort.
- Cultivation (all year).
- Pulling (Jan – Mar). With both hand pulling and grubbing, you must ensure the whold crown of the plant is taken from the ground. Where plants are flowering, flowers should be collected and burnt as seeds can develop from these plants even after they have been pulled from the ground.
- Grubbing (Jul – Mar).
- Slashing (Dec – Mar). Slashing is only a temporary measure to delay flowering. It will not control Ragwort.
- Granules (Apr – Jan). For the use of herbicides applied by boom spraying, spot spraying, wiping or granular application, refer to the DPIPWE Herbicides for Ragwort Control.
- Wiping (Apr – Jan).
- Boom Spraying (Mar – Oct).
- Spot Spraying (Sept – Mar).
- Biocontrol (Jan – Mar). The Ragwort Flea Beetles (Longitarsus flavicornis and L. jacobaeae) are showing promise as effective control means. Spread of the beetle can be increased by collection of adult beetles over the summer months. The Ragwort Stem and Crown Boring Moth (Cochylis atricapitana) and Ragwort Plume Moth (Platyptilia isodactyla) are also having significant impact on plant vigour where they have become established.
N.B. Always check the herbicide label before use.