Erect biennial thistle <2.5m tall & 2m wide. Rosette leaves shiny with prominent white veins & blotches (variegated look). Spiny leaves can grow <60cm long. Sharp spines surround large purple flowers (Nov-Jan) that each produce <200 downy, haired seeds.
Alluvial flats, stockyards, sheep camps other areas of high nitrogen soil levels. Invades pasture areas with summer drought & moist mild winters.
Seed dispersed mostly by wind, also by water, mud, hay, on machinery & animals.
Very competitive, shades other plants. Invades large areas of pasture, unpalatable to stock, reduces pasture productivity. Toxic to cattle, contaminates wool & can harbour pests such as rabbits.
Follow up for seedlings. Maintain good pasture cover to prevent re-establishment.
1. Grub out small infestations before flowering.
2. Spot spray (60ml Tordon BK/10L or 1g metsulfuron/10L).
3. Larger infestations of seedlings can be boom sprayed during early winter or spring. Graze pasture first to remove clover, leave for one week then apply spray. Do not graze for at least 2 weeks after spraying (2,4-D ethylhexyl ester 2-2.5l/ha).
Caution: when using any herbicide or pesticide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.