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June -Thistles

June -Thistles
Scotch thistleScotch Thistle (Cirsium vulgare)

A stout, well-branched biennial thistle that grows from a rosette that can be very large, to a well-branched ‘shrub’ up to 1.5m tall under fertile conditions.  Flowers are a reddish-purple (Nov-Mar), later producing seeds with a mass of thistledown.  In pasture it seems to be strictly biennial, germinating late autumn, winter or early spring, surviving its first summer as a rosette and then flowering in its second summer.

Nodding thistleNodding Thistle (Carduus nutans)

Spiny, robust annual or biennial thistle growing from over-wintering rosettes.  Flower stalks can be 75 cm or more tall, bearing beautiful red-purple or very very rarely white composite flowers (Nov-Feb), followed by seed heads containing many seeds with thistle-down.To set seed a nodding thistle has a vernalisation requirement; that is, it has to go through the colder temperatures of a winter before being reproductive.  This means that an autumn germinated seed will flower and seed in the first summer.  A spring germinated thistle will normally remain as a rosette over the summer, autumn and winter months, until the following spring when it emerges as a very hardy plant ready to bolt to flower and seed during the summer months.  These tough older plants can be very deceptive by having a small amount of leaf area, yet they have a substantial taproot.

Control
Broadcast spraying
  • New pasture and clover selective option – Select* herbicide at 4L/ha.
    It is best to treat the thistle as a seedling or young plant. 
  • Established pasture – Pasture-Kleen* Xtra or Maestro* herbicides at 1.5-2L/ha. Fast drying, fast acting herbicides suitable for changeable weather conditions in the winter.
    Versatill* herbicide can be added at 100ml/ha in addition to the Pasture-Kleen Xtra or Maestro if thistles are very advanced or if you live in an area where nodding thistle has developed resistance to 2,4-D or MCPA.
Spot treatments
  • Tordon* MAX or Versatill herbicides are very effective through a knapsack on thistles of all sizes.
  • Tordon 2G is also a very effective product that is applied dry to the centre of the plant.
  • Scotch and nodding thistles can be chipped out with a hoe, but care must be taken to ensure the entire crown is removed otherwise the plant will regrow.

*Registered trademark of Dow AgroSciences.

Select,  Pasture-kleen Xtra, Maestro, Tordon 2G, Tordon MAX and Versatill are registered pursuant to the ACVM  Act 1997 Nos. P5202, P7316, P3737, P1039, P7231 and P4767.

 

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