grass roots community organisation that aims to improve natural condition of the derwent catchment

Spear Thistle

Disclaimer

The following page is a brief summary of information available on the DPIPWE website regarding Spear Thistle control. For more information view here

Non-chemical control

Physical removal

  • Hand hoeing is effective for individual plants and small patches provided the growing point and the top 20 to 40 mm of the tap root are removed.
  • Cutting or slashing Spear Thistle in late bud or early flower stage can reduce seed production.
  • However, because Spear Thistles mature over an extended period, slashing is unlikely to stop all seed production. In years when there is adequate soil moisture, Thistles are also likely to regrow after slashing.

Cultivation

  • The best method for control of Spear Thistle is to encourage competition from useful plants.
  • Vigorous pasture restricts seedling establishment and growth, and management practices should aim to maintain a vigorous and unbroken sward during the period when Thistles are germinating.
  • In general, cell or rotational grazing should be used in preference to set stocking.
  • Areas of bare ground (for example after insect attack) can result in an invasion of Spear Thistles. Areas left bare by insect attacks should be re-sown with insect resistant pasture grasses such as Phalaris or Cocksfoot.
  • In heavily infested arable areas, growing a cereal crop for one or two seasons can reduce Spear Thistle infestations, provided a suitable herbicide spray program is used (see Herbicides for Spear Thistle Control for more information). Any Thistles not killed by the herbicide will be suppressed by a vigorous crop.

Grazing

  • Spear Thistles are not normally grazed by cattle or sheep. However, cell or rotational grazing can give some control of seedlings.
  • Goats will graze Spear Thistles at the flowering stage, eating flowers, seed heads and stems, and several seasons of goat grazing can significantly reduce Thistle numbers.

Chemical control

Use herbicides in accordance with label. Refer to APVMA permit PER13160 where herbicide is to be used in non-cropping and bushland areas

Application method

1. Boom spray

  • Stage of growth - actively growing
  • Location - Pasture and non-cropping
  • Suggested herbicide - Roundup®Biactive™

2. Spot spraying

  • Stage of growth - actively growing
  • Location - Pasture an non-cropping
  • Suggested herbicide - Roundup®Biactive™