WINGED THISTLE

Winged Thistle – Carduus tenuiflorus

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DESCRIPTION

The winged thistle is a winter annual, which means it usually germinates in autumn, goes through a rosette stage over winter and produces an erect flowering stalk in spring. The plant reaches about a metre in height in the flowering stage. It often forms extensive and dense infestations.

The leaves are spiny and deeply lobed, up to about 30cm long. They are green on top, with some faint white markings, though not nearly as prominently at the variegated thistle.

Flowers are pink-purple, and appear in clusters of up to about half a dozen per stem. The flower is individually about 20mm in diameter. Flowering occurs Nov – Dec. The plant dies after flowering.

The flower stems are prominently ‘winged’ with spiny ribs of leaf material running up the stem, hence the common name of winged thistle.

HABITAT

Pasture land especially hill tops and stock camps, arable land, waste areas, roadsides and lucerne crops. Distributed widely throughout both major islands of NZ.

In most regions of NZ the species is subject to Pest Plant Management Strategies.  

PASTURE MANAGEMENT

Maintaining a dense autumn pasture cover will minimize seedling establishment. Overgrazing in summer can trigger major germinations of this thistle.

PHYSICAL CONTROL

Individual and isolated plants can be chipped or grubbed out. 

HERBICIDES TO CONTROL WINGED THISTLE

Best treated as a seedling or small rosette, in late autumn through to early spring.  

Spot Treatment Herbicides to Kill Winged Thistles

• BuckShot (about half a teaspoon) applied direct to the crushed centre of the rosette. Use more for larger plants.
• GrassMate – 6ml/L by knapsack or 250ml/100L by handgun. (all growth stages)
• MSF600 – 1g/10L by knapsack or 5g/100L by handgun. Very effective but will damage ryegrass and clover. Kills the seed if applied while plants are still flowering. Suitable at all growth stages.
• WHACK – 2,4-D 800 – 45g/10L covering 250m² by knapsack.
• Cut’n’Paste Glimax Professional or MetGel spread as a 2-4mm layer of gel on freshly cut stumps.
• GrassMate XTRA – 6ml/L by knapsack (Rosette and multi-crowned plants)

Boom Spray Herbicides to Kill Thistles (Winged thistle seedlings/rosettes)

Graze before spraying to reduce clover leaf and expose thistle seedlings. Leave for one week to freshen before spraying.

• WHACK – 2,4-D 800 – 2kg/ha on seedlings and 2.5-3kg/ha on rosettes prior to flower stalk development. Clover damage is minimised where clover is largely dormant, or has been hard grazed shortly before spraying.  
• Rainbow & Brown MCPA 750 – 1.5L/Ha for seedlings and 2L/Ha for rosettes before flower stalk development.
• PastureMate – 3-4L/ha. Grass/clover friendly in new and established pasture.

Boom Spray Herbicides to Kill large Winged Thistles

• WHACK – 2,4-D 800 and Rainbow & Brown MCPA 750 will not control mature thistles when used alone.
• Ralid  herbicide used at 100-200ml/Ha in conjunction with either WHACK – 2,4-D 800 or Rainbow & Brown MCPA 750 as above, will control large and resistant thistles. Expect some pasture damage, especially to clovers. Ralid used alone at 1L/Ha is also effective, but clover damage will be severe.

Weed Wiping Herbicides to Control Winged Thistles

• MSF600 – 2-3g/L of water is inexpensive and very effective against erect thistles where pasture is low enough to permit reasonable thistle contact with the roller/wiper.