Spiny Sowthistle
Scientific Name: Sonchus asper
Weed Family: Asteraceae
Description
Spiny sowthistle is a winter annual that is actually in the sunflower family and not a true thistle. The leaves form basal and are deeply lobed. They then alternate on stems. The upper leaves are less lobed but have spiny edges. The stems are hollow and contain hair on only the lower portion. Both the leaves and stems contain a milky solution. The stems only branch in the inflorescence. Spiny sowthistle spreads by seed. It flowers from late spring through the summer, depending on the location. The flower is yellow, resembling a dandelion, but forms in a corymbiform cluster. The root of spiny sowthistle is a taproot. Spiny sowthistle is found throughout the United States.
Herbicide Use
Make your post-emergence herbicide application when spiny sowthistle is young and actively growing. For best results, treat prior to bolting.
Distribution
Germination Dates
Zone-3: May
Zone-4: March-April
Zone-5: March-April
Zone-6: February
Zone-7: February
Zone-8: January
Zone-9: January
PBI-Gordon Product Recommendations
