Persicaria maculosa S.F. Gray
Synonyms - Polygonum persicaria, Polygonum ruderale.
Other names:Lady's thumb.
Summary:A prostrate, annual vine with square stems whose ends are semi-erect. It has dense, reddish flower heads in spring and stem clasping, oval leaves that usually have a dark blotch in the middle.
Two. Oval, 6 to 12 mm long overall with a short merging petiole. Tip round pointed. Edges smooth to slightly undulating. Base tapered. Hairless. Stem red. The hypocotyl is usually short and there is no epicotyl.
First Leaves:The early leaves are oval, develop singly and are 15 to 20 mm long with a short merging petiole. They have a distinct reddish colour and carry a few hairs, mainly on the margin. Tip pointed. Edges slightly undulating with a few hairs. Base tapered. Surface smooth, usually with red marking on the upper surface. Prominent central vein.
Leaves:Do not form a rosette.
Stipules - Membranous sheath at the base of the leaf or petiole.
Petiole - Short or merging on the lower stem leaves and none on the upper leaves.
Blade - Elliptical, red or dark blotch in the middle of the leaf, 50 to 100 mm. Often a few simple hairs on the upper surface and a few simple and glandular hairs on the lower surface and slightly hairy on the margins. Tip pointed. Edges smooth. Base tapered.
Sheath - A membranous sheath is present at the base of the leaf.
Stem leaves - Shorter than the lower leaves and stalkless otherwise similar.
Stems: Low lying initially then bending upwards and erect. Branched, solid, and circular in cross section with shallow longitudinal grooves, up to 800 mm long, Usually reddish. Hairless or scattered star hairs occur along their length.
Flower head:The flowers are axillary and terminal, forming loose to dense spikes up to 35 mm in length.
Flowers: Red, pink, white or greenish in colour, 1-1.5 mm in diameter.
Sepals - 5 petal like sepals.
Petals - 5 petal like sepals.
Fruit:A reddish seed coat encloses the seed but this often falls off after ripening.
Seeds:Triangular pyramid shape, 1.5-3 mm long x 1.5-3 mm wide by 1.5-3 mm thick. Tip pointed. Edges smooth. Flattish. Base squarish with a stalk remnant. Surface smooth and shiny. Sometimes enclosed in a reddish seed coat.
Key Characters:Membranous sheath at the base of the leaf or petiole. Dark blotch in the middle of the leaf.
Annual. Germination occurs in autumn and spring. In New Zealand germination is in spring and early summer (Popay et al, 1995).
Physiology:Competes for N, P, K, Ca and Mg (Casquero et al, 1993).
It is a day neutral plant but flowers more rapidly under short day length conditions (Nakatani and Kusanagi, 1991).
It prefers high N and Ca situations (Borowiec and Kutyna,1990)
Flowering times:Spring in WA.
Spring and early summer in New Zealand.
Seed Biology and Germination:Buried seed dormancy is greater than 3 years (Vleeshouwers et al, 1993)
It has a seasonal dormancy pattern that is determined by temperature (Bouwmeester and Karssen, 1992).
Population Dynamics and Dispersal:
Spread by seed. The main spread is probably as a contaminant in agricultural produce and seed grains such as canola.
Zwerger (1990) gives seed production in spring wheat.
About 8% of the seed bank germinates each year and the seed bank size falls by about 40% each year under cultivated crop conditions with no seed input (Barralis et al, 1988).
Most die within 4 weeks in cattle manure or silage (Schokker, 1988).
Seed production ranged from 880 to 4010 seeds/plant, representing an av. of 2898 seeds/plant during the whole vegetative period (Kostyal, 1985).
Origin and History:Europe.
Introduced over a large area in WA in contaminated canola seed in 1996, but was present in horticultural situations some years before that.
Distribution:NSW, TAS, VIC, WA.
Found in a few isolated areas in the North, North-East, North-West and South of Tasmania.
Courtesy Australia's Virtual Herbarium.
Habitats:Mainly in damp situations but also in free draining soils.
Grows vigorously on a free draining krasnozem soil in Tasmania.
In Poland it occurs on the podsolic, brown, rendzina and chernozem soils (Fijalkowski et al, 1990).
Sultan and Bazzaz (1993) have shown there are various ecotypes suited to a range of conditions.
Used as a medicinal plant in Europe (Koz'-yakov, 1991).
Detrimental:It grows as a weed in both annual and perennial crops and can be strongly competitive.
Weed of cereals, horticulture, canola and orchards.
Alternative host for faba bean (Ditylenchus) nematodes (Augustin and Sikora, 1989).
Major weed of
Beans in Spain (Casquero, 1993), Cereals in Europe,
Crops in New Zealand (Nicholson et al, 1994), Scotland (Simpson Carnegie, 1989), Canada (Freyman et al, 1989) and Northern Ireland (Easson et al,1995),
Cucumbers in the USA (Al-Khatib et al, 1995), Lucerne in Czechoslovakia (Surovcik,1990),
Maize in Germany (Bernhardt et al,1991)and France (Dessaint and Caussanel, 1994), Pears in Germany (Bastian, 1987),
Potatoes in Europe,
Root crops in Poland (Honchol, 1990),
Serradella in Germany (Sieberhein and Stracke, 1988),
Sugar beet in Italy (Proctor, 1993) and Germany (Bernhardt et al, 1991),
Soybeans in England (Berti and Zanin, 1994),
Sunflowers in Yugoslavia (Konstantinovic et al, 1986), Italy (Covarelli, 1986),
Tomatoes in Italy (Pimpini et al, 1986).
Toxicity:It has 7.1% tannins (Smolarz, 1991).
Extracts reduce black bean aphid and its predators (Barczak, 1994).
Legislation:Noxious weed of WA.
Management and Control:DPX-L 5300 (methyl 2-[3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-3-methylureidosulphonyl]benzoate) gave poor control (Kreidi, 1988).
Basagran provided good control in grain legumes (Klaasen et al, 1988).
15 g Granstar/ha gave effective control of Polygonum persicaria in winter wheat (Szalai and Csonka, 1988).
0.75 kg flurochloridone/ha pre-em. in combination with trifluralin provided good control in sunflowers (Beraud and Hutter, 1986).
New isoxazoledicarboxylic acid herbicides are showing good activity (Grossmann and Walter, 1995).
Clomazone has given good results in Cucumbers (Al-Khatib et al, 1995) and pre em in soybeans (Glasgow, 1989).
Triflusulfuron-methyl did not provide control with single applications (Salembier, 1993) but has given good results with multiple applications in sugar beet (Simoneit, 1992).
Harmony (thifensulfuron-methyl) has given good control in maize (Muller, 1992) and pastures in New Zealand (Sanders et al, 1995).
Tribenuron, bromoxynil + ioxynil (1:1 w/w ratio), dichlorprop, dichlorprop + MCPA (534:133 w/w ratio) and bromoxynil + ioxynil + dichlorprop + MCPA (23:38:184:235 w/w ratio) provided good control (Rasmussen, 1993)
Glyphosate 700 g a.i./ha is used in Denmark (Madsen and Jensen, 1995)
Dimethenamid followed by atrazine or dicamba provides good control in Maize (Rahman et al, 1992).
ICIA0051 (2-(2-chloro-4-mesylbenzoyl) cyclohexane-1,3-dione) has given good control (Beraud et al, 1991).
DAS + 1 kg of 2,4-D 25 DAS gave effective control in direct sown rice (Fatemi, 1990)
0.075 kg phenmedipham + 0.1 kg ethofumesate + 0.35 kg metamitron/ha post-em were effective in beets in Belgium (Sysmans et al, 1991).
The presence of surface structures such as trichomes on Polygonum persicaria increase solution retention and salt injury by Ammonium nitrate 20% solutions which is useful in cole and onion crops. (Bitterlich and Upadhyaya, 1990).
Diuron and linuron failed to control Polygonum persicaria but simazine 1 kg a.i./ha provided control in apples and pears (Demeyere et al, 1988).
Bromoxynil + MCPA gave good control in winter wheat (Naoy and Sarpe, 1987)
Bromoxynil provided good control of triazine resistant populations (Wiese et al, 1986).
Solarization provided 78% control (Braun et al, 1988).
In plantations in NZ, >2.2 kg a.i./ha simazine was required for control (Gilchrist, 1988)
Oxyfluorfen provided good control in onions (Zandstra and Wallace, 1988; Gazdag-Torma and Mandoki, 1986).
Consistent use of simazine or atrazine in hops in Poland lead to spread of Polygonum persicaria (Ciota, 1984).
DPX-A7881 [methyl 2-[(4-ethoxy-6-methylamino-1,3,5-triazin-2-yl)carbamoylsulphanoyl]benzoate] gave control in Spring oilseed rape in Canada (Parsons, 1987).
Cyanazine and pendimethalin mixtures in peas gave good control (Reid, 1987).
Devrinol (4kg prod/ha) gave good control in strawberries in Yugoslavia (Jankovic, 1987)
Populations resistant to atrazine occur in New Zealand (RahMan and Patterson, 1987; Rahman, 1990) and the Netherlands (Oorschot, 1989).
Biological Control:Related plants:
Hairy Knotweed (Persicaria subsessilis)
Water Pepper (Persicaria hydropiper) is a native plant that looks very similar but doesn't have the red blotch on the leaves.
Plants of similar appearance:Redshank is distinguished from other members of the dock family by its reddish colour and red stems.
References: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). P199. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P52-53. 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). #952.1.
Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P1113. Diagrams. Photos.
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