Prickly Sowthistle

About the weed

It is an upright annual dicotyledon growing to 120cm. Flowers are pale yellow in loose clusters.

Key features

Plant: The glossy leaves are a rich green and have sharp prickly edges and rounded bases which clasp the stem.

Leaves: The petals are red grey underneath.

Biology

Prickly sow-thistle is less common on arable land than it once was. It occurs mainly in vegetable crops, but can be found in cereals and increasingly in other winter crops. Plants which germinate in autumn overwinter as rosettes, producing flowers in May; 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.

Symptoms & Diagnosis

Life cycle

Seed longevity: >5 years

Germination depth: 5 cm

Seed weight: 0.25 mg

Seeds/head: 100

Seeds/plant: 5000

Treatment

Management

In row crops, hoeing can be used for control where herbicides are not available. In winter cereals, use fallows to reduce seed production. Prickly sow-thistle does not persist in grassy rotations.