Common Groundsel
Senecio vulgaris
Washington State Classification
Class C — Widespread, County-Selected Control
Common groundsel is a problem weed in cultivated crops, gardens and nurseries.
Quick Reference
Identification
Growth Habit
The plant is usually a winter annual, sometimes biennial, though it may germinate in all seasons. It grows from 4 to 18 inches tall.
Leaves
Leaves are deeply lobed with toothed margins and may be smooth to hairy. They have little, or no, stalks and are alternately arranged on the stem. Basal leaves are usually purplish on the under surface, 1 to 4 inches long and 1/2 to 1-1/2 inches wide.
Flowers
Flowerheads are numerous, with yellow disk flowers, but no ray flowers. The heads are cylindrical, 1/4 to 1/2 inch long, with black-tipped bracts around the base.
Fruit & Seeds
The seeds are slender, ridged, about 1/2 inch long, and tipped with a tuft of silky white hairs.
Impact
Common groundsel is a problem weed in cultivated crops, gardens and nurseries. It is poisonous to cattle and horses and toxic to humans. It contains pyrrolizidine alkaloids, which can cause irreversible liver damage and possibly death.
Ecology & Spread
Habitat
This weed is found in many crops including forages, cereals, mint, berries, and row crops, as well as in ornamentals and vegetable gardens. Please click here to see a county level distribution map of common groundsel in Washington.
Spread Mechanisms
Reproduction
Groundsel produces abundant seeds which spread by floating on the wind with their parachutes of hair. One groundsel plant can produce as many as one million seeds in a season.
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Control Methods
Mechanical
- Common groundsel can be controlled by tillage in the fall and early spring. New plants can still establish in newly cultivated soil from the reservoir of seeds in the soil or from seeds blown in from adjacent areas.
Cultural / Prevention
- Weed infestation can be reduced by cultivation methods such as rototilling or hoeing, where practical. Reduce weed infestation by handpulling weeds. Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.
Biological Control
- Larvae of the cinnabar moth, Tyria jacobaeae, are released extensively in western Oregon and western Washington for biological control of tansy ragwort. It also eats groundsel, but these caterpillars are not capable of significantly reducing a groundsel infestation because they are only present from June through August.