Broadleaf weeds

Broadleaf weeds such as Paterson’s curse, St John’s wort and thistles can rapidly dominate pastures, especially where bare patches are increasing and pastures are set-stocked.

Broadleaf weeds have the following characteristics:

• often have poor digestibility compared to desirable pasture species
• seeds of some broadleaf weed species contaminate wool, damage hides and cause animal health problems
• some species can poison livestock slowly over time, eg St John’s wort and Paterson’s curse
• many species form dense patches over large areas, excluding stock from grazing
• often produce a lot of long-lasting seed, eg St John’s wort, Onopordum or Illyrian thistle seeds can remain viable for 12 years or more
• often not grazed by livestock, except at the early rosette stage, when broadleaf weeds are more digestible

Livestock will graze young broadleaf weeds when stock densities are high enough to overcome selectivity, and the pasture has been rested to encourage a more upright growth habit in the weeds.