© Hermann Geissel 2004 - Leaving Certificate Agricultural Science - http://www.agscience.ie
Problem Weeds in Cereals
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Reproduced here by kind permission.
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A brief glossary has been added.
Contents:
Loose Silky-bent
Annual Meadow-grass
Black-grass
Wild-oat
Common Chickweed
Scented Mayweed
Common Hemp-nettle
Red Dead-nettle
Knotgrass
Ivy-leaved Speedwell
Field Pansy
Goose-grass (Robin-run-the-hedge, Bedstraw, Cleavers)
GLOSSARY
Name:
Loose Silky-bent; Apera spica-venti
Family:
Habitat:
Occurs especially on sandy and
loamy soils rich in nutrients and low
in lime
Germination period:
Predominantly in the autumn but also
in the spring
Flowering period:
Characteristics:
20-100 cm in height
Ligules 3-10cm, deeply fringed
Leaf base without auricles
Youngest leaf rolled
Leaves non-hairy
Name:
Annual Meadow-grass; Poa annua
Family:
Habitat:
Prefers compact sandy loam or pure
loam and clay soils well provided with
nutrients
Germination period:
Almost throughout the year
Flowering period:
Almost throughout the year
Characteristics:
Up to 30 cm in height
Ligules 2-5 mm long, collar-shaped, thinly membranous
Leaf base without auricles
First leaf folded
Leaves non-hairy
Lamina along the middle vein with two lengthwise grooves
Leaf with boat-shaped tip.
Name:
Black-grass; Alopecurus myosuroides
Family:
Habitat:
Occurs generally on sandy or pure
loams rich in nutrients
Loam and clay indicator plant
Germination period:
Flowering period:
Characteristics:
20-80 cm in height
Long ligule, generally irregularly dentate
Leaf base without auricles
First leaf rolled
Leaves non-hairy
Name:
Family:
Habitat:
Prefers newly-turned, damp loam and clay soils rich in nutrients
Germination period:
Predominantly in spring but also in the autumn
Flowering period:
Characteristics:
Up to 150cm in height
Ligules up to 6mm long, membranous
Leaf base without auricles
Youngest leaf rolled
Leaf sheath and margins ciliate towards the leaf base, otherwise non-hairy
Name:
Common Chickweed; Stellaria media
Family:
Habitat:
Widespread
Encountered especially on humus
containing sandy to loamy soils
very rich in nutrients
Nitrogen indicator plant
Germination period:
Flowering period:
Almost throughout the year
Characteristics:
5-30cm in height
Generally prostrate and bolster forming
Foliage leaves opposite in pairs and pointed to egg-shaped
Stem with single line of hair down each internode.
Name:
Scented Mayweed; Matricaria chamomilla
Family:
Habitat:
On sandy or pure loam and clay soils, rich in nutrients, varying in
humus content and generally low in
lime
Loam indicator plant
Germination period:
Flowering period:
Characteristics:
Leaves deeply and finely pinnate
Stem bare, generally branching
Name:
Common Hemp-nettle; Galeopsis tetrahit
Family:
Habitat:
On humus-containing, preferably
stony to sandy loams rich in
nutrients
Germination period:
Flowering period:
Characteristics:
Up to 50 (80) cm in height
Foliage leaves longish to eggshaped, pointed at the tip, margin toothed, stalked
Stem erect, often branching, smooth,
round and distinctly thickened at
the nodes
Name:
Red Dead-nettle; Lamium purpureum
Family:
Habitat:
On newly-turned sandy or pure loam
soils rich in nutrients
Nitrogen indicator plant
Germination period:
Throughout the year but mainly in autumn
Flowering period:
March to September (winter flowering plant)
Characteristics:
Up to 25cm in height
Foliage leaves crosswise opposite, stalked, covered with soft hairs,
distinctly veined
Stem with square cross-section
Name:
Knotgrass; Polygonum aviculare
Family:
Habitat:
Predominantly on humus-containing
sandy and loamy soils rich in
nutrients
Nitrogen indicator plant
Germination period:
Flowering period:
Characteristics:
Up to 50cm in height
Generally prostrate, richly branched, bolster-forming
Longish foliage leaves with very short petioles, enveloped at the
base of the stalk by a thin, transparent, non-ciliate, slit membrane (leaf sheath of stipule)
Name:
Ivy-leaved speedwell; Veronica hederifolia
Family:
Habitat:
Humus-containing, sandy-stony or pure loam soils rich in nutrients
Loam indicator plant
Germination period:
Mainly in autumn but also in spring
Flowering period:
Characteristics:
Up to 30 cm in height
Leaves heart to ivy shaped, mostly 3-lobed (sometimes up to 7 lobes),
ciliate, stalked
Stems prostrate and strongly branched at the base, with scattered hairs
Name:
Field pansy; Viola arvensis (V. tricolor, subspecies arvensis)
Family:
Habitat:
Sandy or loamy soils varying in humus content and rich in nutrients
Germination period:
Throughout the year but with peaks in the autumn and spring
Flowering period:
Almost throughout the year but mainly from May to October
Characteristics:
Up to 30cm in height
Foliage leaves sinuate to notched, with slightly wavy margins
Leaves narrowing towards the stalk
Small stipules at the base of the stalk
Name:
Goose-grass (Robin-run-the-hedge, Bedstraw, Cleavers); Galium aparine
Family:
Habitat:
On sandy or pure loam and clay soils rich in nutrients and humuscontaining
Loam and nitrogen indicator plant
Germination period:
Flowering period:
Characteristics:
Up to 120cm in height
Spreading climber
Leaves longish and pointed and arranged 4-8 in whorls, covered at
the edge and on the underside with curved prickles
Stem also covered with prickles and square in cross-section
Auricles:
Small ear-like appendages at the base of the leaf (e.g. Sorrel)
Bolster:
A thick pad like a pillow
Ciliate:
With fine hairs around the edge (e.g. young Beech leaf)
Dentate:
Internode:
The space on a stem between two neighbouring nodes
Lamina:
Ligule:
A small, thin projection from the top of the leaf-sheath in grasses
Lobed leaf:
A leaf that is divided, but not into separate leaflets (e.g. Ivy, Sycamore leaf)
Membranous:
Thin, dry and semi-transparent
Node:
The point in a stem where a leaf is attached
Petiole:
Pinnate leaf:
A leaf with leaflets arranged in pairs on opposite sides of a common stalk
Prostrate:
Lying close to the surface of the ground
Sinuate:
Having a deep wavy outline (e.g. mature Beech leaf)
Stipule:
A leaf-like appendage usually at the base of the petiole
Whorl:
A ring of leafs around a stem (at the same node)
© Hermann Geissel 2004 - Leaving Certificate Agricultural Science - http://www.agscience.ie