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

Crop Protection Online

1.12 2024

Weed biology
_{Agro-region: Denmark}

Polygonum persicaria L.

Can be mistaken for

Polygonum lapathifolium L., of which the surface of true leaves is very hairy.

Characteristics

Cotyledons
Almost oval with entire leaf margins. Stalked. The surface is often sparsely hairy. Length approx. 7-10 mm.

True leaves
Oval to lancet-shaped with entire leaf margins. Unstalked. Almost smooth surface. Length approx. 18-40 mm.

Mature plant
Redshank is a medium-sized (30-50 cm), erect plant. It is especially known by the black spots in the middle of the true leaves and by the spikelike inflorescences. The diameter of the flower is approx. 2 mm. Seed production: Up to approx. 800 seeds per plant.

Seed
Two types. The main type like Pale Persicaria, but plumper. The other type is somewhat triangular with rounded edges. The surface of both types is almost smooth, often showing remnants of the perianth. Thousand grain weight approx. 2.7 g.

Biology

Propagation and dispersal
Only through seeds.

Habit
Summer annual.

Importance

The species is found most frequently in spring-sown crops throughout Denmark, but can also be found in autumn-sown crops. It thrives in waterlogged soil and can cause large yield losses, even in competitive crops such as cereals and Oil-seed Rape.

For treatment options, consult 'Herbicides Across'.
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Taxonomy

Polygonaceae.

Names in different languages

Danish :	Pileurt, fersken
German :	Floh-Knöterich
English :	Redshank
Latin :	Polygonum persicaria L.
Norwegian :	Hønsegras
Swedish :	Åkerpilört

Seedling

Early stage

Flower

Mature plant

Seeds

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Weed biology Agro-region: Denmark