Prickly sow-thistle
Weed profile of Prickly sow-thistle (sonchus asper). Discover growth habits, herbicide resistance and impact in UK cereal production.
Young plant
The cotyledons are oval and short stalked. The first true leaves are edged with backward-pointing teeth, and the overall shape that of a rounded diamond. The leaf is a dull blue green colour and the edge may be tinged with purple.
Mature Plant
The branched stem is smooth and hollow. The leaves are a glossy rich green and clasp the stem with rounded bases.
Flower
Flowerheads are pale yellow, 20-25mm across, and form loose clusters. Petals are reddish-grey beneath. The base of the flowerhead is flask -shaped, becoming more pronounced as it grows older.
Height 120cm
Prickly Sow-thistle Fact Sheet
| Key feature | - Leaves are glossy and have sharp prickly edges and rounded bases that clasp the stem - taproot - Mid yellow flowers |
|---|---|
| Number of seeds produced per plant | 5,000 |
| Seed shed | May-October |
| Germination period | March-July and September to November |
| Germination depth | 5 cm |
| Primary dormancy | Low |
| Does it have a secondary dormancy? | Yes |
| Seed longevity | >5 years |
| Factor promoting germination | Light |
| Rate of seed decline with cultivations | High |
| Lifecycle | Plants which germinate in autumn overwinter as rosettes, producing flowers in May/june; plants germinating in spring flower in June. The latter can set seed in 10 weeks. Prickly sow-thistle only reproduces by seed and is distributed by wind |
| Geographical Location | Widespread in England and Wales |
| Soil Type | Nitrogen rich loams or nutrient rich sandy and stoney soils which are not too dry |
| Impact | Increasing found in arable rotations particularly in winter crops. Autumn germinating plants can overwinter as rosettes and flower in May, spring germinating plants flower in June 5% yield loss from 50 plants per m2 |
| Resistance risk | No resistance in the UK but populations resistant to ALS herbicides in France, Norway, USA and Canada |
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