What is ragwort?
- Ragwort is a serious pasture weed.
- Ragwort is a
declared weed under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of ragwort are prohibited in Tasmania.
How to identify ragwort
Image top: Ragwort rosette, © D. Elliott.
Images above (L-R): Paddock infested with ragwort, © S. Leighton; Flowering ragwort, © T. Rudman.
- Ragwort lives for two years if left undisturbed. Most seed germination occurs in autumn, and the plant forms a rosette (in its first year a cluster of leaves close to the ground), and in its second year an erect plant up to 1.5 m in height with convoluted dark green leaves and bright yellow flowers. The flowers are formed at the end of small branchlets resulting in a characteristic flat-topped flower arrangement.
- When growing in pasture, ragwort often lives for more than 2 years due to damage to the plant from stock hooves, grazing and cutting. When plants are damaged, new shoots are produced from the original stem or from larger roots left in the ground. These damaged plants can produce large bushes of many flowering stems, and flower multiple times over several years.
- For help in identifying ragwort, search the
Dennis Morris Weeds and Endemic Flora database. If you are still in doubt about the weed you are dealing with, contact Biosecurity Tasmania on 03 6165 3777 for help.
Ragwort in Tasmania
- Ragwort is widely distributed throughout the grazing areas of Tasmania, with the exception of the Midlands where it occurs only in small patches. Ragwort also occurs on the shores of several lakes on the Central Plateau, and along roadsides in many areas of the state. The heaviest infestations occur on poorly managed pastures.
- Ragwort is a serious pasture weed in Tasmania. Ragwort plants are extremely competitive, and competition from ragwort causes a significant reduction in pasture production. Ragwort is also poisonous to most types of livestock. Stock losses due to ragwort poisoning can occur where stock are forced to graze ragwort due to food shortages.
What is the legal status of ragwort in your area?
Detailed management and control guidelines for ragwort can be found in the Ragwort Control Guide. Refer also to
Herbicides for Ragwort Control
. For further information see
Weed Links and Resources
Herbicides for Ragwort Control
Statutory Management Plan for Ragwort
Weed links and resources
Other useful links
Ragwort Control Guide
- Plan your control program, this will save time and money in the long-run;
- Ensure cultivation, harvesting and road-grading machinery used in an infested area is washed down to remove any ragwort seed;
- Maintain a dense and vigorous pasture to prevent ragwort establishing;
- Consider cropping a paddock infested with ragwort to reduce the infestation;
- Take careful note of
stock withholding periods after spraying to avoid stock eating the treated ragwort;
- Seek a vendor declaration to identify weeds which may be present in purchased feed and grain;
- Use a dedicated feedout area to avoid spread of weeds that may come in purchased feed and grain.
- Don't introduce ragwort to ragwort free areas (e.g. by failing to wash down machinery and equipment between sites);
- Don't start your control program without first planning your approach;
- Don't rely on slashing to remove ragwort - plants will quickly resprout;
- Don't expose stock to dense ragwort infestations in case of poisoning.
Spread of ragwort
- Spread of ragwort is by seed. The majority of seeds are deposited within 20 m of the parent plant but may be dispersed up to a kilometre or more by strong winds.
- Seeds can also be spread on the coats of animals, on farm machinery, logging equipment, trucks and other vehicles, and in contaminated hay.
Avoid the introduction of ragwort
- Preventing the introduction of ragwort to ragwort free areas is the best means of control. Good hygiene practices are vital.
- Farm machinery, logging equipment, trucks and other vehicles can carry ragwort seeds. Thorough cleaning of cultivation, harvesting and road-grading machinery which has been working in infested areas will greatly reduce the risk of spread into other areas.
- Hay and crop seeds can contain ragwort seed if they have been sourced from infested paddocks.
- See the
Washdown Guidelines for Weed and Disease Control for detailed information on how to wash-down equipment and personnel to reduce the chance of spreading ragwort.
- Cutting or slashing flowering ragwort stems with no other follow up is ineffective as the plants quickly recover and flower again within a few weeks.
- Pulling or grubbing ragwort can be effective but only if the crown and larger roots are completely removed from the ground. Regrowth from small roots left in the ground can occur, although the regrowth from smaller roots tends to be weaker and take longer to re-establish.
- Pulling is best carried out at the flowering stage, but this is only possible if the soil is reasonably loose.
- Grubbing may be carried out at any stage of growth. Use a pick or fork to loosen the soil so that the plant can be removed with the roots intact. A mattock or hoe is not a suitable tool for grubbing since large roots or parts of the crown are likely to be cut off and left in the ground.
- Ragwort plants should be collected and destroyed after pulling or grubbing. This avoids the possibility of stock eating the plants (which are more palatable when wilted). Flowers should always be removed and destroyed to remove the seed.
- Ragwort material can be destroyed by deep burial (at least 1 m depth).
- Pasture improvement is an essential part of any control program. Maintenance of a dense vigorous pasture reduces the opportunity for ragwort to establish and spread.
- Degraded pasture lacking a high proportion of perennial ryegrass and clover (or other suitable grass/legume mix) may need to be ploughed and resown to provide effective competition with ragwort.
- Where ragwort is well established the area should be cropped for at least one year before resowing to pasture.
- Cropping a paddock infested with ragwort is an effective way of reducing the infestation. Repeated cultivation destroys established plants and exhausts seed reserves in the soil.
- A herbicide program in the crop will improve the control achieved during cropping. Suitable crops include cereals, peas, poppies, and forage crops.
- In non-arable areas where pasture establishment is difficult (stony or rocky ground, steep hillsides and gullies), establishing trees such as radiata pine and eucalypts can provide an effective way of suppressing ragwort.
- This is a long term control measure and will not control the ragwort until canopy closure and dense shading occurs. Interim control measures are essential.
- Sheep will graze ragwort at both the rosette and the flowering stages.
- Sheep grazing can reduce an infestation but will not destroy all plants and seed. Following grazing, ragwort plants may recover quickly and produce new shoots. Follow up measures are essential.
- Continuous exposure of sheep to dense ragwort infestations should be avoided as poisoning may become a problem.
- Biological control is the use of a living species, usually an insect, mite or disease, to control a weed.
- Biological control will not eradicate ragwort, but can be used in conjunction with other control methods.
- Biological control agents that have been released in Tasmania include the ragwort flea beetle, the stem and crown boring moth, and the ragwort plume moth.
- For more information on biological control programs in Tasmania contact the
Tasmanian Institute of Agriculture.
- A number of herbicides are registered for use on ragwort in Tasmania (see
Herbicides for Ragwort Control for more information).
- Ragwort herbicides may be applied by boom, spot spray or wiping equipment, or as granules, depending on the herbicide and the density and extent of the infestation.
- Herbicides are most effective at the seedling or rosette stage and when the plants are actively growing. Autumn and spring are the usual seasons for herbicide control of ragwort.
- Take careful note of the
stock withholding periods following spraying. For dense infestations, it is best to exclude stock completely from the area until the treated plants are dead.
- For smaller infestations, any stock allowed to graze the area should be carefully watched to make sure that ragwort is not being consumed.
Herbicides for Ragwort Control