Agropyron repens

Scientific Name Agropyron repens
Common Names English: Quackgrass; German: Quecke; French: Chiendent officinal
Description A. repens is an aggressive perennial grass, which reproduces by seed and spreads by a shallow mass of long, slender, branching rhizomes. The plants are very resistant to drought and frost.

Descriptions

Characteristic Features

The rhizomes are usually yellowish-white, sharp-pointed, somewhat fleshy and up to 3 m (9.84 ft) long. The auricles clasp the stem, which helps to immediately distinguish it from most other grass weeds. Another characteristic feature is the long and narrow spike.

Young Plant

The first leaf is very long and wide without hairs on the lower surface.

Stems

Erect, 30 to 120 cm (11.81 - 47.24 inch), round, more or less curved at the base.

Leaves

The leaf blades are soft and relatively flat, slightly soft-hairy, dull and mostly dark green, sometimes glaucous, 6 - 30 cm (2.36 - 11.81 inch) long and 3 - 15 mm (0.12 - 0.59 inch) wide. The youngest leaf is rolled, the ligule membranous and short, truncate. Auricles occur at the junction of the sheath and blade. Sheaths are without hair.

Propagatio Organs

Flowers

The inflorescence is a dense to rather lax spike, like a wheat spike but more slender. Spikelets are compressed, usually with 4 to 8 flowers set in two rows attached to the broad side of the spindle. Glumes are 5 - 15 mm (0.197 - 0.59 inch) long, lanceolate and mostly awn-pointed, lemmas aristate, 6 - 11 mm (0.23 - 0.43 inch) with an awn from less than 1 mm (0.039 inch) up to about 10 mm (0.39 inch).

Flowering Period

Summer, rarely through autumn.

Fruit

Flat, with furrow; hairy at the apex.

Seeds

Germination occurs all year around, from up to 5 cm (1.97 inch) soil depth. The seedlings begin to develop rhizomes when they have 4 to 6 true leaves. The rhizome tips are sharp-pointed and can penetrate hard soils, roots, and tubers. New plants can grow from rhizome fragments, e.g. after discing an infested field.

Viability Of Seeds

The seed can remain viable up to 4 years under field conditions.

Propagation

A. repens reproduces mainly vegetatively from rhizomes but also sexually by seed. New rhizomes grow primarily in summer (up to 3 m (9.84 ft) per year). Tillage operations that cut existing rhizomes into smaller pieces may increase the quckgrass infestation since from every segment a new plant may emerge. Low temperatures and long day conditions in summer induce rhizome growth, new tillers develop in spring and fall. The plants commonly produce 40 - 60 seeds per stem, also immature seed (dough stage) can germinate. Low light intensities induce shoot growth.

Occurrence

Habitat

A. repens grows in all moderate climate zones of all continents.

Soil

The weed flourishes on many types of soils, mineral as well as organic soils. A. repens is most competitive on fertile soils, which are rich in nitrogen with a good water supply and is less successful on very acid or very dry, shallow soils. A high N-content in the soil favors rhizome growth and bud production.

Additional Crop Information

Found in all arable crops and grassland of moderate climates, but mainly in European cereal production.

Agricultural Importance

Quackgrass reduces productivity of crops, rangeland and pasture. It is also a nuisance in lawns, ornamentals and home gardens and reduces growth and germination of neighboring plants by release of allelochemicals. A contamination of seed grain crops reduces the value of the harvest. Reduction of tillage intensity favors quackgrass.

Control

Integrated Crop Management

Tillage is most successful in dry soils that facilitate dessication of the rhizomes. In the spring, tillage should be repeated when plants regrow to approximately 5 cm (1.97 inch) in height. If soils are too wet for tillage, mowing, close grazing has improved control and prevents seed production. Heavy pasturing or mowing before tilling may enhance control.

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