Charlock

Sinapis arvensis L.

Synonyms - Brassica sinapistrum, Brassica kaber.

Family: Brassicaceae.

Names:

Sinapis is from the Greek sinapi meaning mustard.
Arvensis is from the Latin arvum meaning cultivated field and refers to the plants association with cultivation.
Charlock

Other names:

Wild Mustard.

Summary:

An erect, annual plant with lobed and toothed leaves and sweet smelling yellow, 4-petalled flowers in spring forming erect, beaked pods about 50 mm long with obvious veins.

Description:

Cotyledons:

Two. 8 to 15 mm long x 10 to 20 mm wide. Tip indented. Sides convex. Base tapered. Surface hairless. Petiole longer than the blade,10 to 25 mm long, and is hairless. The seedling has a long hypocotyl and a reddish purple epicotyl.

First Leaves:

Grow singly, 20-70 mm long, round tipped with a short petiole, and are hairy. The first leaf is not lobe or shallowly lobed at the base, but second and subsequent leaves usually have lobes which are completely separated. The lobes are usually toothed. The degree of leaf hairiness is variable.

Leaves:

Forms a rosette 150 to 350 mm in diameter.
Petiole - On basal leaves only.
Blade - Bright green, up to 200 mm long, lobed and coarsely toothed, usually with the end lobe, rounded and larger than the others, usually smooth and shiny but may be rough with scattered bristly hairs.
Stem leaves - Alternate. Lower stem leaves, which reach 300 mm in length, are stalked and usually lobed at the base. The upper stem leaves are much shorter, triangular, pointed tipped have short or no petioles, and are lance shaped, obviously veined, with toothed edges and without basal lobes. Scattered hairs are usually present on the upper and lower surface.

Stems:

Stout, erect, 300-1400 mm tall, solid with a pithy core, fluted or circular in cross section with shallow grooves, dark longitudinal striations, branch at the base and along their length. Stems usually darken on drying. Scattered, bristly hairs. The degree of hairiness is very variable.

Flower head:

Flowers in racemes on the ends of stems.

Flowers:

Bright yellow, 12-25 mm in diameter with a sweet aroma.
Ovary -
Sepals - Spreading.
Petals - 4, bright yellow. 9-12 mm long
Stamens -
Anthers -

Fruit:

Erect, cylindrical pod, 20-60 mm long x 2-4 mm diameter, 2 celled, 3-5 nerves on each cell, with 3-12 seeds per cell, slightly constricted between the seeds or wrinkled, smooth or slightly hairy, held away from the stem on a thick, 3-7 mm long stalk. The top third is a broad, cone shaped beak, 10-15 mm long which has 0-2 seeds in its base. Valves 3 nerved. Opens when ripe to release seed.

Seeds:

Spherical, 1-2 mm diameter, red-brown to black.

Roots:

Taproot.

Key Characters:

Cotyledons conduplicate.
Sepals spreading
Petals yellow.
Pods at least 3 times as long as broad, sub cylindrical, diverging from the axis, beak long and usually thick, dehiscent, seeds in 1 row.
Valves 3-7 nerved.
Adapted from J.M. Black.

Biology:

Life cycle:

Annual. Seed germination occurs mainly in the autumn to winter and it rapidly produces rosette of leaves, crowding companion plants. The flower stem emerges in spring and produces flowers and pods. Pods split when ripe to release the seed. It dies in summer.

Physiology:

Reproduction:

By seed.

Flowering times:

October in western NSW.
August to December in SA.

Seed Biology and Germination:

Vegetative Propagules:

None.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread by seed mainly as a contaminant of grain and agricultural produce.

Origin and History:

Southern Europe. Northern Africa. Asia.

Distribution:

NSW, QLD, SA, TAS, VIC, WA.
Widely distributed in the South of Tasmania, but much more localised and restricted in distribution in the Northern half.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Mediterranean.

Soil:

More abundant on heavy than on light soils. Also on red soils.

Plant Associations:

Significance:

Beneficial:

Leaves used as a salad or cooked vegetable in Europe and Scandinavia.
May be eaten by stock when young.

Detrimental:

Weed of crops, cultivation, roadsides and disturbed areas.
Important in cereals and most winter crops due to its strong competitive habit and its ability to overgrow and swamp crops.
May taint milk and meat.

Toxicity:

Seeds poisonous to cattle and pigs when fed as a contaminant of grain.

Symptoms:

Gastro enteritis.

Treatment:

Don't feed contaminated grain.

Legislation:

Management and Control:

Normal grazing usually provides reasonable control. Spray Grazing with 2,4-D amine or Tigrex® is cheap and reasonably effective in pasture or bushland areas.

Thresholds:

Eradication strategies:

Buy grain and produce from Charlock free areas.
Manually remove isolated plants.
Prevent seed set. Spray small infested areas with 10 g/ha Eclipse® plus 500mL/ha of Brodal® plus 1% spray oil in winter each year.
Most of the Brassicaceae weeds have dormant seeds that continue to germinate throughout the season and for several years. They often mature and set seed very quickly. Manual removal is effective but must be done at least every 8-10 weeks. Once pods are formed, seed will often mature even if the plant has been uprooted. Soil disturbance often leads to a flush of seedlings.
Many are somewhat unpalatable, so grazing only offers partial control. They often flourish in under-grazed, sunny areas.
In bushland situations, fairly selective control can be achieved with 100 mL spray oil plus 0.1 g Eclipse® or 0.5 g Logran® in 10 L water. 5 mL Brodal® is often added to this mix to provide residual control of seedlings. Spray the plants until just wet from the seedling stage up to pod formation.
Isolated plants should be removed manually and burnt if flowering or seeding and a 10 m buffer area sprayed with 10 mL Brodal® in 10 L water.
500 mL/ha of glyphosate(450g/L) can be used at flowering to reduce the seed set of most species on roadsides without causing significant damage to most native plants.
Wick application with 1 part glyphosate(450g/L) in 2 parts water or overall spraying with 100 mL glyphosate(450g/L) in 10 L water provides reasonable control of most Brassicaceae species though Wild Radish tends to regrow.

Herbicide resistance:

Biological Control:

Related plants:

Flax-leaf Alyssum (Alyssum linifolium)
Wall Cress (Arabidopsis thaliana)

Black Mustard (Brassica nigra)
Broccoli (Brassica oleracea var. italica)
Brussels Sprouts (Brassica oleracea var. gemmifera)
Cabbage (Brassica oleracea var. capitata)
Cauliflower (Brassica oleracea var. botrytis)
Chinese Cabbage (Brassica chinensis)
Indian Mustard (Brassica juncea)
Kale (Brassica oleracea var. acephala)
Kohlrabi (Brassica oleracea var. gongylodes)
Mediterranean Turnip (Brassica tournefortii)
Rape or Canola (Brassica napus var. napus)
Rapeseed (Brassica rapa var. sylvestris)
Savoy cabbage (Brassica oleracea var. sabauda)
Smooth Stemmed Turnip (Brassica barrelieri subsp. oxyrrhina was Brassica oxyrrhina)
Swede (Brassica napus var. napobrassica)
Turnip (Brassica rapa var. rapa)
Twiggy Turnip (Brassica fruticulosa)
Winter Rape (Brassica napus var. biennis)
Brassica elongata

Sea Rocket (Cakile maritima)
White Ball Mustard (Calepina irregularis)
Shepherd's Purse (Capsella bursa-pastoris)
Common Bittercress (Cardamine hirsuta)
Wood Bittercress (Cardamine flexuosa) is not in WA.
Ward's Weed (Carrichtera annua)
Wall Rocket (Diplotaxis muralis)
Sand Rocket (Diplotaxis tenuifolia)
Heliophila pusilla
Oval Purse (Hornungia procumbens was Hymenobolus procumbens)

Argentine Peppercress (Lepidium bonariense) is often found around granite rocks.
Common Peppercress (Lepidium africanum) is common in WA.
Field Cress (Lepidium campestre) has clasping stem leaves.
Garden Cress (Lepidium sativa)
Hoary Cress (Lepidium draba was Cardaria draba)
Lesser Swinecress (Lepidium didymum was Coronopus didymus)
Matted Peppercress (Lepidium pubescens)
Perennial Peppercress (Lepidium latifolium)
Virginian Peppercress (Lepidium virginicum)
(Lepidium oxytrichum)
(Lepidium perfoliatum)

Sweet Alyssum (Lobularia maritima)
Common Stock (Matthiola incana)
Night-scented Stock (Matthiola longipetala)
Muskweed (Myagrum perfoliatum) is not in WA.
Ball mustard (Neslia paniculata)

Cultivated Radish (Raphanus sativus).
Sea Radish (Raphanus maritimus).

Turnip Weed (Rapistrum rugosum)
Watercress (Rorippa nasturtium-aquaticum)
White Mustard (Sinapis alba) has white seed.
Charlock (Sinapis arvensis)

Sisymbrium altissimum is not in WA.
Smooth Mustard (Sisymbrium erysimoides)
London Rocket (Sisymbrium irio)
Hedge Mustard (Sisymbrium officinale)
Indian Hedge Mustard (Sisymbrium orientale)0
Sisymbrium runcinatum
African Turnip Weed (Sisymbrium thellungii) is not in WA.

Succowia balearica is in Kings Park in Perth.

Plants of similar appearance:

Charlock is extremely difficult to separate in the seedling stage from Wild Radish. In general the first leaf of Charlock does not carry lobes at the base, while that of Wild Radish does. This characteristic, however is not definitive. The leaves of Radish are rough, while those of Charlock tend to be smoother and rather shiny. The leaf tip tends to be more rounded. Charlock, unlike Wild Radish, seldom forms a completely flat rosette, the leaves being usually semi-erect. In the mature plant the petal shape and size serves to distinguish the two species; Charlock flowers are always bright yellow while those of Radish are pale yellow, lilac, or white. In Radish the sepals are pressed against the back of the petal, while in Charlock they stand away. Charlock petals are shorter and broader than those of Radish, and are not veined.
Wild Turnip is also very similar. It can be separated in the seedling stage by its leaves, which have 'warts' on the upper surface and are broader in relation to their length, and in the mature stage by the upper stem leaves which are sessile and clasping.
White Mustard (Sinapis alba) has stalked upper leaves.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P136-137. Diagram. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P378. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P332-333. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P216-217.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P120.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P44-45. Diagrams.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1136.2.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P84. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.