Sorrel means reddish brown colour and refers to the colour of the seed heads.
Other names:
Red Sorrel
Sheep Sorrel.
Summary:
Sorrel is a rhizomatous, patch forming slender herb with red-brown seed heads that are 100-500 mm tall mainly from August to December. The acid-tasting leaves are arrow-shaped, 2-5 cm long with a pointed tip and two basal lobes. The tiny reddish tinged flowers are arranged in whorls up the slender flower spikes and each flower has small floral segments only 2 mm long. The male and female flowers are on separate plants, the male flowers with 6 stamens and the female flowers with 3 fringed style tips. The nut-like fruit is enclosed between the enlarged inner 3 floral segments. It has annual tops with a perennial, rhizomatous root system. It is native to Europe and Asia and has become a problem weed of crops, pastures, roadsides and waste places.
Sorrel flowers in autumn, spring and summer and was previously known as Rumex acetosella.
Description:
Cotyledons:
Two. Long, narrow, club shaped, 10-15 mm long by 2-4 mm wide, tip round, top frosty with a short merging or no petiole. Hairless. The seedling has a hypocotyl but no epicotyl.
First Leaves:
Develop singly, oval, 6-20 mm long, top frosty, on a stalk(petiole), 6-15 mm long. Hairless. Tip round to slightly pointed. Membranous sheath at the base of the petiole. The blade of the first leaves tapers into the petiole, but on later leaves basal lobes are formed giving the leaf an arrow shape.
Leaves:
Form a loose, untidy rosette. Acid sour taste. Variable and often arrow shaped. Hairless.
Stipules - (Ochrea) Membranous sheath encircling the stem, translucent, 7-17 mm long, jagged, triangular, silvery white sheath at base of petiole.
Petiole - 40-120 mm long.
Blade - Arrow shaped (Triangular with lobes at base). 15-200 mm long by 5-25 mm wide. Tip pointed. Hairless. Lobes at the base are rarely lobed again.
Stem leaves - Elliptical or arrow shaped. Alternate. Lower leaves 40-70 mm long by 3-5 mm wide and stalked. Upper ones smaller and may have no petiole. Tip pointed. Membranous sheath at base. Hairless.
Stems:
Erect, slender, wiry, 100-600 mm tall, solid, round or polygonal with lengthwise grooves, often with brown/red stripes, branched. Hairless. Flowers on the upper half. Acid taste.
Flower head:
In clusters or rings of 5-8 towards the ends of the stem branches forming loose, leafless, erect, reddish, rarely branched panicles. Clusters are well separated along the many branched stems. Separate male and female plants.
Flowers:
Small, 2-4 mm wide on jointed, 1-2 mm stalks. Green turning red to brown. Single seeded.
Bracts - Membranous, translucent, 2 mm long sheath(ochreola).
Ovary - 3 styles with large, tufted stigmas.
Perianth - 6 almost equal segments, 1 mm long, 3 inner ones enlarged and close over the fruit in the female plant.
Stamens - 6, in the male plant.
Anthers -
Fruit:
Egg shaped, smooth edged achene with 3, oval, network patterned, valves, 0.75-1.75 mm long by 1 mm wide, usually slightly shorter than and attached to the nut. No tubercles. Achene on stalks(pedicels), 2 mm long that hold it away from the stem.
Seeds:
Triangular pyramid, hard nut, netted surface, dark brown, smooth, shiny, 1-2 mm long. 1 seed per flower and fruit. Seed remains enclosed within the fruit.
Roots:
Spreading, creeping, underground rhizome up to 7 mm thick. Root fragments will form new plants. Rhizomes produce shoots every 25-100 mm.
Key Characters:
Perennials.
Leaves hastate, with acute lobes at the base.
Fruiting perianth inconspicuous.
Perianth lobes 6 and all a similar size.
Flowers unisexual, dioecious, in loose panicles, 5-8 per whorl.
Fruit valves shorter than nut.
From J.M. Black, N.T. Burbidge and G. Perry.
Biology:
Life cycle:
Perennial. Seeds germinates and roots form shoots from autumn to spring. Vegetative growth mainly occurs over winter and spring and it flowers from August to December. The top growth normally dies off in summer leaving the dormant, perennial, root system protected by the soil.
Physiology:
Intolerant of shading.
Tolerates drought, frost, snow.
Reproduction:
By seed and rhizomes and rhizome fragments.
Flowering times:
September to December in SA.
August to December in Perth.
Spring and summer in WA.
September to November in SE Australia.
Seed Biology and Germination:
Seeds remain viable in the soil for many years.
Many seeds are dormant.
Seed survives passage through the gut.
Vegetative Propagules:
Rhizomes and rhizome fragments.
Hybrids:
There are several subspecies distinguished by their fruit. Ssp. angiocarpus is the most common.
Allelopathy:
Population Dynamics and Dispersal:
Spread mainly by rhizome fragments being moved by cultivation.
Extension of root system increases the size of patches by up to 2000 mm per year.
Also spread to new areas by seed in stock or as a contaminant of hay or pasture seed.
Some seed traded and planted intentionally.
Origin and History:
Europe. Mediterranean. South west Asia.
Throughout Tasmania.
Distribution:
ACT, NSW, QLD, SA, TAS, VIC, WA.
Avon wheatbelt, Esperance plains, Jarrah forest, Mallee, Swan coastal plain and Warren regions in WA.
New Zealand, USA
Habitats:
Prefers full sun.
Climate:
Temperate. Mediterranean.
Tends to be more abundant in higher rainfall areas but significant infestations can occur in all cropping areas.
Soil:
More abundant on acidic sandy or loamy soils. Tolerant of low fertility soils.
Weed of crops causing severe yield reductions due to competition.
Interferes with cultivation because the extensive root system blocks tyned machines.
Spread by cultivation.
Weed of crops, pastures, orchards, gardens, vineyards, vegetables, roadsides, wetlands, bushland, streams, granite outcrops and disturbed areas.
High oxalate content makes it unpalatable and occasionally toxic.
Toxicity:
May cause oxalate poisoning in stock. Breeding ewes are the most sensitive.
Legislation:
None.
Management and Control:
Repeated applications of glyphosate, metsulfuron and dicamba can provide very high levels of control.
Ploughing in spring before flowering followed by repeated tyned cultivation or root raking over the summer to bring the rhizomes to the surface, so they dry out and die, provides some control but may cause unacceptable erosion risks on many of the light soils that sorrel prefers. Planting a tall vigorous crop, such as barley or oats, and application of selective herbicides should follow this.
Avoid spreading rhizomes to clean areas when cultivating.
Grazing and cultivation in winter generally makes the infestation worse.
Mowing is ineffective.
Thresholds:
Eradication strategies:
Manual removal is rarely successful and extremely difficult due to the extensive rhizomatous root system and attempts often lead to greater infestations.
Spray top in spring with 400 mL/ha of glyphosate(450g/L).
Apply 800 mL/ha glyphosate(450g/L) plus 40 g/ha Logran® plus 5 g/ha Ally® plus 1 L of Pulse Penetrant® per 400 L of spray mix, 2-3 weeks after the break. Cultivate 5 days later and plant wheat.
OR Apply 1200 mL/ha glyphosate(450g/L) plus 3 g/ha Ally® plus 1 L of Pulse Penetrant® per 400 L of spray mix, 2-3 weeks after the break and cultivate 10 days later and plant oats or barley.
6-8 weeks after planting apply 5 g/ha of Ally® in wheat and barley crops or 750 mL/ha of dicamba amine(200g/L) in oat crops. Tordon®242 is also used in cereal crops.
In following break crops use triazine or urea herbicides to reduce the establishment of sorrel from dormant seed.
In following clover pastures, Spray Graze with 750 mL/ha of 2,4-D amine(500g/L) 6-8 weeks after the break of the season to prevent seedlings establishing. Repeat this annually for at least 5 years.
Avoid cultivating from infested areas to clean areas because this will move root fragments, which are the main form of spread for Sorrel.
In bushland areas, hand spray with a mix of 0.2 g metsulfuron(600g/kg) plus 25 mL Pulse Penetrant® in 10 L water in winter. On small areas, use 0.2g metsulfuron(600g/kg) plus 1 g Oust® plus 25 mL Pulse Penetrant® in 10 L water in winter to control existing plants and provide residual control of seedlings and rhizomes. This mix will kill most broadleaved seedlings. Repeat annually if plants appear. 1 year after the last spray replant to tall growing perennial species.
50 mL glyphosate(450g/L) in 10 L water applied in winter is reasonably effective but tends to leave the area bare.
In bushland areas, hand spray until just wet with a mix of 0.2 g metsulfuron(600g/kg) plus 25 mL Pulse® in 10 L water in winter or spring. On small areas, add 0.5 g Oust® for residual control of seedlings and rhizomes. This mix will kill most broad-leaved seedlings. Repeat annually if plants appear. One year after the last spray, replant to tall growing perennial species.
50 mL glyphosate(450g/L) in 10 L water applied in winter is reasonably effective but rarely achieves eradication.
Mowing and grazing are ineffective. Cultivation in spring and summer provides some control as it desiccates the root system but may also spread the infestation.
Herbicide resistance:
Fairly tolerant to desiccant sprays such as paraquat, diquat, bromoxynil and oxyfluorfen. Fairly tolerant to group C herbicides such as atrazine, simazine and diuron.
Biological Control:
None.
Related plants:
Bladder Dock (Rumex vesicarius)
Broadleaf Dock (Rumex obtusifolius)
Clustered Dock (Rumex conglomeratus)
Curled Dock (Rumex crispus)
Fiddle Dock (Rumex pulcher)
French Sorrel (Rumex acetosa) is a cultivated form of Sorrel.
Mud Dock (Rumex bidens)
Rambling Dock (Rumex sagittatus)
Shiny Dock (Rumex crystallinus)
Swamp Dock (Rumex brownii)
Wiry Dock (Rumex dumosus)
Plants of similar appearance:
Creeping Knotweed (Polygonum prostratum)
Bladder Dock (Acetosa vesicarius)
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P207. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P281. Diagram.
Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P128-129. Photo.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P153, 155. Diagram of seed.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P583.
Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). P54. Photos.
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). P200-201. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P54-55. Diagram.
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). #1072.1.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P115.
Meadly, G.R.W. (1965). Weeds of Western Australia. (Department of Agriculture - Western Australia). P70-73. Diagrams. Photo.
Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P459.