Crop Protection Online > Pests - Weed biology<br> <sub>Agro-region: Denmark</sub> - Centaurea cyanus L.

Crop Protection Online

26.4 2024

Weed biology
_{Agro-region: Denmark}

Centaurea cyanus L.

Can be mistaken for

Characteristics

Cotyledon
Oval with entire leaf margins. Stalked. Smooth surface. Length approx. 10-15 mm.

True leaves
Lancet-shaped, leaf margins slightly sinuate with small, dark tips. Stalked. Densely hairy surface. Length approx. 22-30 mm.

Mature plant
Cornflower is a large plant with a 40-80 cm high, erect stem. Leaves and stems are tomentosely hairy. The species is in particular known by its large, blue flower heads. The diameter of the flower head is approx. 30-40 mm. Seed production: Up to approx. 1,500 seeds per plant.

Seed
Pitcher-shaped with oval cross section. A tuftlike accumulation of reddish brown hairs is seen at the top. A tilted stigma is found near the base. Thousand grain weight approx. 4.5 g.

Biology

Propagation and dispersal
Only through seeds.

Habit
Winter annual.

Importance

The species is occasionally found in autumn-sown crops throughout Denmark, but its distribution is declining. In the crops in which the plant is found it can cause quite heavy losses, even at relatively small densities.

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Taxonomy

Compositae.

Names in different languages

Danish :	Kornblomst
German :	Kornblume
English :	Cornflower
Latin :	Centaurea cyanus L.
Norwegian :	Kornblom
Swedish :	Blåklint

Seedling

Early stage

Flower head

Mature plant

Seeds

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Weed biology Agro-region: Denmark