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Plantwise Technical Factsheet

common reed (Phragmites australis)

Host plants / species affected
Beta vulgaris var. saccharifera (sugarbeet)
Brassica napus var. napus (rape)
Gossypium (cotton)
Oryza sativa (rice)
Saccharum officinarum (sugarcane)
Solanum tuberosum (potato)
Triticum aestivum (wheat)
Zea mays (maize)
Description
P. australis is a robust erect perennial grass, aquatic or subaquatic, growing to 4 m high (occasionally 6 m), strongly tufted, with an extensive rhizome system. Stolons may also be present. Stems rigid, many-noded; internodes hollow. Leaves alternate, up to 70 cm long, with a ligule of hairs (resembling short eyelashes) up to 1.5 mm long; leaf blade flat, up to 60 cm long and 8-60 mm wide, tapering to a spiny point, rigid, glabrous or sometimes covered with a whitish bloom; leaf sheaths loose and overlapping. Inflorescence a feathery, drooping panicle 15-50 cm long, often tan-brown to purplish; many-flowered; branches slender, ascending; spikelets several-flowered, 10-18 mm long, with florets exceeded by rachilla hairs; first glume 2.5-5 mm long; second glume 5.7 mm long; lemmas thin, 3-nerved, densely and softly hairy; nerves ending in slender teeth, the middle tooth extending into a straight awn; seed slender, dark brown.
Prevention and control
Introduction

Effective management programmes for Phragmites are usually based on burning, the use of plastic mulch, discing, chemical control, cutting, grazing, dredging, and draining or the manipulation of the water table and salinity (Marks et al., 1994).

Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:
- PAN pesticide database (www.pesticideinfo.org)
- Your national pesticide guide

Biological Control

The few natural enemies (Rhizedra lutosa and Archanara geminipuncta) that have been recorded for this weed have not been thoroughly evaluated for host specificity. Some attention has been paid to the possibilities of inundative control of Phragmites reeds using insects in Australia, although the approach does not appear to have been widely used there (Wapshere, 1990).

Grass carp (Ctenopharyngodon idella) will eat the young shoots of developing Phragmites reeds, but they are not generally preferred species (Nikanorov and Polyakova, 1980). However, in fallow rice paddies in Japan, Tsuchiya (1979) reported that grass carp weighing 0.5-2 kg grazed areas of 4-30 m² in fallow paddies, controlling P. australis, as well as Typha latifolia and Isachne globosa.

Cultural Control

Cutting is a standard control measure, but tends to produce highly variable results. For example, Kay (1995) used a hand-held weed trimmer equipped with a saw blade to clear reed vegetation to within 15 cm of the hydrosoil surface at marsh study sites in North Carolina, USA, providing nearly 2 years effective control. However, in UK drainage channel systems, frequent winter mowing promoted the growth of P. australis and adversely affected drainage efficiency (Milsom et al., 1994).

Cutting or other harvesting methods are often considered to be the least-damaging of available control methods for the environment (Ditlhogo et al., 1992). Kampichler et al. (1994) found no consistent deleterious effects of regular harvesting on the herbivorous arthropod population of reeds growing in Lake Neusiedler, Austria. Multivariate analysis of plant growth and arthropod incidence data showed a generally variable response of the fauna to cutting, due to the heterogeneity of the reed stands.

Autumn ploughing 25-27 cm deep for rhizome exposure and desiccation followed by reploughing in spring is effective against the common reed in Russian rice crops. Fragmented rhizomes soon die under a layer of water and this method is reported to be very effective if carried out every year (Agarkov and Gruzdev, 1980).

In Dutch reed stands, Mook and van der Toorn (1982) found that damage to just-emerging shoots in April or early May by burning (wet- and dry-burned plots) or early ground-frost (dry-burned and dry-mown plots) retarded growth of leaves and shoots for about 1-2 weeks, but the relative growth rate and maximal levels reached were not significantly lower than in undamaged areas. Heavy damage by late ground-frost (dry-burned plot) or by the stem-boring larvae of Archanara geminipuncta (wet-undisturbed plot) lowered the maximal shoot biomass by about 25-35%. Heavy infestation by the rhizome-boring larvae of Rhizedra lutosa (dry-undisturbed and dry-mown plots during later years) gave losses in yield of about 45-60%.

Winter harvesting and burning influence the geometric (stem diameter and relative wall thickness) and the mechanical properties (modulus of elasticity and breaking stress) of reed culms (Ostendorp, 1995), weakening the plants and making them more susceptible to other control measures.

Integrated Control

Integrated control may be used in eradication programmes aimed at weed growths of Phragmites reeds. For example, in Egypt, Ahmed (1990) reported that a regime consisting of 2 applications of dalapon combined with burning 10 weeks after the second application, followed by ploughing in conjunction with the removal of dead rhizomes with the ploughed soil, and finally flooding, gave near-complete control of a dense stand of P. australis in a dry pond of 3000 m². Less than 5% of the initial plant cover had regenerated 10 months after herbicide application.

Cane growers in South Queensland (Australia) have advocated an integrated programme for reed control using deep ploughing followed by rotary hoeing, which can destroy most of the root system of P. australis, but is unlikely to provide complete eradication. Two applications of dalapon gave rapid, short-term control, whereas two applications of glyphosate showed slower, but longer-term control (Izatt, 1979).
Related treatment support
 
External factsheets
IRRI Factsheets, International Rice Research Institute (IRRI), English language
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