Ragwort Control Guide


Do's and Don'ts of ragwort control

Ragwort rosette, Photo D. Elliott

Do's

  • 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'ts

  • 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.

Physical removal

  • 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).

Cultivation

Pasture
  • 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
  • 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.
Trees
  • 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.

Grazing

  • 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

  • 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.

Chemical control

  • 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.
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    To the extent permitted by law, the Tasmanian Department of Primary Industries, Parks, Water and Environment (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using information or material (in part or in whole) contained on this website.

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