The Australian Wine Research Institute

Figure 1. Common sowthistle (courtesy of HerbiGuide)

Description: Common sowthistle (Sonchus oleraceus L.) is an erect, hairless, branched annual or biennial herb about 1 m tall with a taproot and hollow stems which have a milky sap. The basal leaves are up to 30 cm long, form a rosette and are soft and lobed or toothed. The yellow dandelion-like flower heads are clustered, each about 2 cm in diameter, with all the florets having a radiating petal-like blade. 

Life cycle: Common sowthistle is an annual or short-lived perennial weed. Seeds germinate from autumn to spring and it grows mainly in the cooler months. It usually flowers in spring and dies after flowering finishes in summer.

As a soil indicator: Common sowthistle is found in most soil types.

Dispersal: Common sowthistle reproduces and is spread by seed that is mainly dispersed by wind. Surface seed is short-lived but buried seed will survive for two to three years. Few seeds will germinate if buried more than 2 cm deep.

Legislation: None

Non-chemical control methods: Mow or graze in spring to prevent seed set. Establish competitive crops to prevent re-establishment.