Integrated Pest Management
Annual Sowthistle
Sonchus oleraceus
Annual sowthistle (Forest and Kim Starr, Starr Environmental, Bugwood.org)
Annual sowthistle flowers and seeds (Chris Evans, University of Illinois, Bugwood.org)
Description
- plant with upright growth between 1 and 4 feet in height
- hollow stems branch toward the sky and produce elongated Hershey kiss-shaped heads that open to yellow, dandelion-like flowers
- flowers mature to globe-shaped fluffy white seed heads
- each brown seed is carried in the wind by a tuft of white fluff
- leaves are green to bluish-green in color, toothed and have prickly margins
Location
- commonly grows in planting beds
Life Cycle
- annual with germination from spring to fall; peak germination occurs in late spring
- seedlings form a rosette 6 weeks post germination and produce flowers 9 weeks post germination
- flower heads continue to bloom from mid-summer to mid-fall; flowers open for 2 days and seed production occurs 1 week after blooms open
IPM Recommendations
- Hand-pull plants in planting beds prior to seed maturation.
- Shallow tillage or hoeing will control young plants in planting beds.
- Apply a mulch layer 3 inches deep on planting beds to reduce seed germination.
- Apply an appropriate post-emergent herbicide directly to target weeds.