Hawkweed

(Hieracium (syn. Pilosella) species)
Note: orange hawkweed Hieracium aurantiacum is now Pilosella aurantiaca subsp. aurantiaca

Hawkweed 

What is hawkweed?

  • There are a number of introduced hawkweed species which are potential weeds in Tasmania.
  • Hawkweed is a weed of native grasslands and pastures.
  • Hawkweed is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of hawkweed are prohibited in Tasmania.

How to identify hawkweed

  • Hawkweeds are perennial (long-lived) herbs belonging to the daisy family.
  • Orange hawkweed stems grow to 40 cm high and have numerous blackish hairs. The flowers are bright orange and daisy-like while the leaves occur as a rosette (or whorl) at the base of the plant and are also hairy. Leaves usually grow at a slight angle to the ground but under grazing pressure and harsh conditions they lie flat.
  • Seed germinates throughout the growing season, especially in autumn. Plants grow rapidly and usually flower within the first growing season, but flowering may be delayed in late germinating plants. Seedlings establish readily on bare areas.
  • Orange hawkweed plants produce between four and eight leafy runners (called stolons) that can reach lengths of 25 cm. Runners grow from buds in the rosette when the plants are flowering. These runners form new rosettes so that a patch continues to expand until it covers the site with a solid mat of hawkweed.
Hawkeed Hawkweed
Image top & above left: Hawkweed flowers, © Louis-M Landry.
Image above right: Hawkweed infestation, © Louis-M Landry.

Hawkweed in Tasmania

  • Two species of hawkweed have been recorded in Tasmania: orange hawkweed Pilosella aurantiaca (syn. Hieracium aurantiacum) has naturalised at several sites, while mouse-ear hawkweed Pilosella officinarum (syn. Hieracium pilosella) established at one site but has now been eradicated.
  • Hawkweed has been found in open woodland and grasslands, poor pastures, roadsides and neglected areas in the Southern Midlands, Central Highlands and around Hobart. Hawkweed is also occasionally found in the ornamental and herbal plant trade.
  • Hawkweed colonises spaces between tussock grasses, often in higher altitude areas, and can be extremely invasive. Heavy infestations form large swards which prevent regeneration and survival of native species and reduce productivity in grazing areas.

What is the legal status of hawkweed in your area?

What you need to do

  • If you locate orange hawkweed anywhere in Tasmania, or if you find a plant that you think could be orange hawkweed, immediately contact Biosecurity Tasmania on 03 6165 3777 to report this weed.
Detailed management and control guidelines for hawkweed can be found in the Hawkweed Control Guide. Refer also to Herbicides for Hawkweed Control. For further information see DPIPWE's Weed Links and Resources.

See also
Herbicides for Hawkweed Control
Hawkweeds Statutory Weed Management Plan
Weed Links and Resources

Other useful links
City of Hobart - Orange Hawkweed Control Program
Weeds in Australia - Weed Management Guide
Pest Genie
APVMA

Hawkweed Control Guide

Do

  • Plan your control program, this will save time and money in the long-run;
  • Consider the impact of your control methods on off-target species, especially if herbicides are used;
  • Ensure machinery and equipment is washed down between sites or prior to contractors leaving site;
  • Carefully time your use of herbicide for best results (see the Herbicides for Hawkweed Control for more information);
  • Coordinate your control program with neighbouring landholders where your weed problem crosses property boundaries;
  • Revisit and regularly inspect the site and ensure follow-up is undertaken;
  • Use a combination of different control methods; and
  • Establish vigorous pasture (or native species) after removal to reduce re-infestation.

Don't

  • Don't introduce hawkweed to hawkweed-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 allow hawkweed to flower and set seed before treatment;
  • Don't rely on one attempt at removal - follow-up is essential;
  • Don't rely on just one control method.

Spread of hawkweed

  • Orange hawkweed spreads by runners over short distances and by seed over larger areas.
  • Seeds have minute barbs which enable them to stick to hair, fur, feathers, clothing and vehicles, and be carried long distances.
  • Seeds can be dispersed by wind and water, and in dumped garden waste and contaminated soil. They may also be spread by snow clearing and road maintenance machinery.
  • 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 hawkweed.

Physical removal

  • Small infestations of hawkweed can be removed by digging out the shallow-rooted rosettes.
  • Ensure the whole plant, including all roots and runners, are removed, as plants quickly regrow from fragments if any pieces of runners or roots are left behind.
  • Be careful when removing flowers and seedheads so that seeds are not accidentally dispersed. Flower and seedhead material should be burned.
  • Mowing can prevent seed production by removing flowering stems. However repeated mowing can stimulate growth of runners and worsen an infestation.

Cultivation

  • Establishing a competitive, well managed pasture or lawn area can reduce the size and impact of hawkweed infestations.
  • On cropping land, establishing a competitive crop can control hawkweed, especially where herbicides are also used in the cropping system.

Chemical control

  • Under an off-label permit issued by the Australian Pesticides and Veterinary Medicines Authority (APVMA), there are herbicides registered for the control of hawkweed in Tasmania. See Herbicides for Hawkweed Control for more information.

Herbicides for Hawkweed Control

Herbicides for Hawkweed Control


Important Disclaimer
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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