Solanum Elaeagnifolium

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Data sheets on quarantine pests Fiches informatives sur les organismes de quarantaine

Solanum elaeagnifolium

Indiana, Kansas, Kentucky, Louisiana, Maryland, Mississippi, Identity Missouri, Nebraska, Nevada, New Mexico, North Carolina, Scientific name: Solanum elaeagnifolium Cavanilles Ohio, Oklahoma, Oregon, South Carolina, Tennessee, Texas, Synonyms: Solanum dealbatum Lindley, Solanum flavidum Utah, Washington) Torrey, Solanum hindsianum Bentham, Solanum leprosum Central America and Caribbean: Guatemala, Honduras, Ortega, Solanum roemerianum Scheele, Solanum saponaceum Puerto Rico Hooker fil in Curtis, Solanum texense Engelman & A. Gray, South America: Argentina, Chile, Paraguay, Uruguay Solanum uniflorum Meyer ex Nees Oceania: Australia (all states). Taxonomic position: Solanaceae Common names: Silver-leaf nightshade, white horse-nettle, History of introduction and spread tomato weed, silverleaf nettle, bitterleaf nightshade, bitter apple, silverleaf bitter apple, bull nettle, prairie berry (English); S. elaeagnifolium is native to north-east Mexico and south-west morelle jaune (French); ölweidenblättriger, nachtschatten USA where it is a weed (Robinson et al., 1978). It is also (German); meloncillo del campo, quillo-quillo, revienta caballo, considered native to Argentina, the nature of the insect tomatillo, trompillo (Spanish); Tähtikoiso (Finnish); паслёи herbivorous fauna suggesting that this distribution is secondary. линейнолистный (Russian); bitterappel, bloubos, satansbos, It has been introduced to other parts of North America including silwerblaarbitterappel (Afrikaans); chouka assafra, chouika, California and Florida and is now widespread in all but the chouk jmel, hassika matechat jmel, zririga (in Morocco) Great Lakes and New England regions (USDA-NRCS, 2005). Notes on taxonomy and nomenclature: The name Solanum Invasions of the weed have also occurred in Australia, southern elaeagnifolium is universally accepted, though the species India, South America, southern Africa and around the displays considerable morphological variation, especially in Mediterranean Basin. Further spread is very likely. It was the Americas, confusing its taxonomic status. Morton (1976) newly recorded in southern Taiwan and the Penghu Islands in proposed that the Argentine form was a separate subspecies, but 2002 (Hsu & Tseng, 2003). It is reported but unconfirmed in Symon (1981) concluded that this form also occurs in North Turkey. America and is thus a natural variant of the same species. Introduction to Morocco is believed to have resulted from the Several varieties and forms have been described, though clonal import of contaminated crop seeds in 1958 (Tanji et al., 1984), reproduction permits the coexistence of different variants, and it now infests 50 000 ha in the Tadla region and it is spreading suggesting that classification at the varietal level should be to other regions such as El-Kelâa des Sraghna and Marrakech. avoided unless genetic differences are confirmed (Stoltsz, In South Africa, it is thought to have been imported as a 1994; Heap & Carter, 1999) contaminant of pig fodder around 1905 (Wassermann et al., EPPO code: SOLEL 1988), and/or hay during the 1940s or 1950s, being recorded as Phytosanitary categorization: EPPO A2 List no. 342 a problem in 1952 and declared a weed in 1966. Similarly, infestations in South Australia are linked to imports of contaminated hay from North America during the 1914 Geographical distribution drought, although the weed was first recorded in New South EPPO region: Algeria, Croatia, Cyprus, Egypt, France, Greece, Wales in 1901 and then in Victoria in 1909 (Heap et al., 1997). Israel, Italy, Republic of Macedonia, Morocco, Serbia and Later infestations in Western Australia appeared from Montenegro, Spain, Syria, Tunisia contaminated Sudan grass (Sorghum sudanense) introduced Asia: India (Karnataka, Tamil Nadu), Israel, Taiwan from eastern Australia (Heap & Carter, 1999). In the USA, Africa: Algeria, Egypt, Lesotho, Morocco, South Africa, where the plant is native to some south-western States, contam- Tunisia, Zimbabwe inated ballast and bedding used in railway cattle wagons led to North America: Mexico, USA (Alabama, Arizona, Arkansas, the introduction of the weed into California in 1890 (Goeden, California, Colorado, Florida, Georgia, Hawaii, Idaho, Illinois, 1971).

Solanum elaeagnifolium 237

Morphology

Plant type S. elaeagnifolium is a seed- or vegetatively-propagated (therophyte, chamaephyte, hemicryptophyte or geophyte), broadleaved herbaceous and woody perennial.

Description S. elaeagnifolium is multistemmed, up to 1 m tall, the aerial growth normally dying back during winter, with an extensive root system spreading to over 2 m deep (Fig. 1). The term ‘rhizome’ cannot be used in the case of this plant as fragments Fig. 2 S. elaeagnifolium seedling. Surroundings of Kairouan, Tunisia, May on any part of the roots can regenerate. 2006. Photo: Sarah Brunel. Stems are cylindrical, sparingly branched, with a few scattered reddish prickles, herbaceous except at the base. Leaves are dark green to pale greyish green, petiolate, lanceolate, obtuse or acute at the tip, rounded or truncate at the base, with entire or wavy margin, 2.5Ð10 (max 16) cm long and 1Ð2.5 (max 4) cm wide, petiole 0.5Ð2 cm long, sometimes slightly lobed or with undulate margins (Figs 2 & 3). Leaves, stems and calyx are densely pubescent, giving the plant its typical silver-green appearance. Foliage is covered with star-shaped hairs. Yellow- to brown-coloured prickles usually occur on the stems and also the main veins of the leaves. The inflorescence is a solitary cyme of 1–7 flowers, with long peduncules (5Ð20 mm). The calyx measures 5Ð7 mm, with 2Ð 4 linear lobes. The corolla is 25Ð35 mm large and is orbicular, generally bright blue to purple but sometimes white with yellow anthers of 7Ð9 mm (Fig. 4). The fruit is an irregularly dehiscent berry, initially spherical, green (with white patches) and fleshy, drying and becoming yellow to orange (10Ð15 mm in diameter) at maturity (Fig. 5). Fig. 3 S. elaeagnifolium invading a potato field. Surroundings of Kairouan, A single plant generally produces 40Ð60 fruits, each containing Tunisia, May 2006. Photo: Sarah Brunel.

Fig. 1 Extensive root system of S. elaeagnifolium. Berre l’Etang, Bouches-du- Fig. 4 S. elaeagnifolium inﬂorescence in a wheat ﬁeld. Surroundings of Rhône, France, April 2005. Photo: Christelle Chevrat. Kairouan, Tunisia, May 2006. Photo: Sarah Brunel.

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Similarity to other species In the EPPO region, S. elaeagnifolium is very distinct from other native or introduced Solanum spp. Elsewhere in the world, it has been confused with S. coactiliferum, S. esuriale and S. karsensis in Australia (Heap et al., 1997; Heap & Carter, 1999), S. carolinense in Texas, USA (Gorrell et al., 1981), and S. panduriforme in South Africa where hybrids have also been identiﬁed (Wassermann et al., 1988). However, variation within introduced populations is considered to be the result of multiple introductions rather than hybridization with native Solanum species (Stoltsz, 1994; Heap et al., 1997). (See Notes on taxonomy and nomenclature, above.)

Biology and ecology

General S. elaeagnifolium is a perennial geophyte with roots, summer- growing, dying back in late autumn, and surviving off its rootstocks during the winter. It has four different growth forms: from seeds (as a therophyte) germinating from spring through summer; from buds above soil level giving new shoots in spring (chamaephyte); from buds at Fig. 5 Fruit of S. elaeagnifolium. Surroundings of Kairouan, Tunisia, May the soil surface (hemicryptophyte); from buds buried in the soil, 2006. Photo: Sarah Brunel. which regenerate from its roots (horizontal or vertical), from which new shoots arise (geophyte). It mainly reproduces vegetatively, from buds on underground fragments. Fragments as small as 0.5 cm long and as deep as 20 cm deep can regenerate. Sections of taproot may maintain their viability for up to 15 months (Molnar & McKenzie, 1976). Ten-day-old seedlings are able to regenerate. Sprouting is enhanced by the removal of the aerial parts of the parent plants or by cultivation. This aggressive vegetative growth from deep rootstocks makes S. elaeagnifolium very difficult to control, both mechanically and chemically. Reproduction by seed is secondary, though seeds are highly viable and last at least 10 years in soil. High levels of dormancy and infrequent germination can lead to the establishment of extensive viable seed banks. Studies indicate that 10% of seed is still viable after passing through the digestive tract of sheep (Washington State Noxious Weed Control Board, 2006). Seeds require fluctuating temperatures to germinate. Boyd & Murray (1982) obtained a maximum Fig. 6 S. elaeagnifolium invading an olive orchard. Surroundings of germination rate of 57% when they germinated seeds at 20°C Kairouan, Tunisia, May 2006. Photo: Sarah Brunel. for 16 h and at 30°C for 8 h; light and darkness had no effect. They also found that a pH of 6 or 7 was optimal for germination. Other work indicates that immersing seeds in running water for relatively long periods may improve germination rates 60 –120 seeds, smooth, flat, greenish-brown, 2Ð3 mm in diameter, (Rutherford, 1978). Factors controlling seed germination are closely resembling those of tomatoes. poorly understood, however, the reproductive biology of Invasions of croplands and pastures by S. elaeagnifolium are S. elaeagnifolium is comprehensively reviewed by Heap & Carter most conspicuous during midsummer when the plants are (1999), Parsons (1981) and Richardson & McKenzie (1981). flowering (Fig. 6). In such infestations, the plants are easily The life cycle of the plant is composed of 5 phases: vegetative identified by the abundance of blue or purple flowers and the regeneration and germination during spring; vegetative develop- orange-yellow mature berries that appear later in the season. ment, the duration of which depends on the biotope; flowering

Solanum elaeagnifolium 239

vegetation are not normally invaded, this is facilitated by trampling caused by livestock.

Environmental requirements S. elaeagnifolium tolerates Mediterranean, steppe and mild climates with relatively high summer temperatures and low annual rainfall (Parsons, 1981; Heap et al., 1997). It has been suggested that cool summers and high annual rainfall are factors that could prevent invasion in certain areas (Heap & Carter, 1999) and this is consistent with the distribution of the weed in Australia and South Africa. However, in Europe, its northern potential limit may be more dependent on winter temperatures. Established plants are sensitive to frost and waterlogging but are tolerant to saline conditions and highly resistant to drought (Wassermann et al., 1988). Full sunlight is most favourable for growth, and shading reduces plant vigour. It requires high temperatures (20Ð34°C) for normal germination and growth. Germination is advanced under favourable moisture conditions, notably heavy rains, and by alternating temperatures. Once established, the plants are highly resistant to drought and are widespread in semiarid areas, but will also thrive under irrigated conditions in these areas. Although summer-growing, the weed is very adaptable climatically and, in Australia, also occurs in winter rainfall areas (Cuthbertson et al., 1976). It is recorded at up to 1200 m altitude (Californian Department for Food and Agriculture, 2006). Fig. 7 An infestation of S. elaeagnifolium on a roadside, probably S. elaeagnifolium can adapt to different soil types. For introduced with the growing media of the ornamental plant. Surroundings of example, in Australia, the heaviest infestations were observed Kairouan, Tunisia, May 2006. Photo: Sarah Brunel. on sandy soils with low organic matter (Heap & Carter, 1999).

Climatic and vegetational categorization from spring to the end of summer and fructification from the S. elaeagnifolium is found in areas with a hot dry summer and end of spring until autumn. a cool wet winter. In its native range, it seems hardy only to Pollination is believed to occur via insects. Individual plants zone 9 (Ð7 to Ð1°C) but as a weed it is hardy to zone 6 (Ð23 to produce up to 200 berries per growing season, approximating to Ð18°C) as, for example, in the USA. It is associated with the 1500Ð7200 seeds per plant. Factors influencing seed ecology, following vegetation zones: Mediterranean sclerophyllous viability and germination are comprehensively reviewed by forests and temperate steppes. Heap & Carter (1999), who report the chromosome number of S. elaeagnifolium as 2n = 24. Uses and benefits Despite its confirmed adverse toxicity to livestock (e.g. Habitat Dollahite & Allen, 1960; Molnar & McKenzie, 1976), South S. elaeagnifolium is mainly a weed of cultivated land, orchards, African cattle and wild antelope browse S. elaeagnifolium managed grasslands and associated man-made habitats such as during spring and early summer with no ill effects (Wassermann natural grasslands, riverbanks/canalsides, rail/roadsides and et al., 1988), and the plant has also been pelleted and wastelands (Fig. 7). It appears to be adapted to a wide range of successfully fed to livestock. The steroidal alkaloid Solasodine habitats and soil conditions, but appears mostly in areas of used in the preparation of contraceptive and corticosteroid relatively low annual rainfall (250Ð600 mm) (Parsons, 1981; drugs has been commercially extracted from S. elaeagnifolium Heap & Carter, 1999). In Australia and South Africa, the largest berries in India (Maiti, 1967) and Argentina, making it the infestations occur in cropping and grazing land, with smaller most promising source among Solanum species investigated infestations found in irrigated pastures, orchards and vineyards, (Heap et al., 1997). Recent studies have identified other roadsides, channel banks and stockyards (Wassermann et al., potential uses for S. elaeagnifolium as plant extracts have 1988; Heap & Carter, 1999). In particular, the weed thrives on shown moluscicidal and nematicidal activity, as well as disturbed land and although undisturbed pastures and natural cancer-inhibiting activity.

240 Data sheets on quarantine pests

S. elaeagnifolium competes for moisture and nutrients with Pathways of movements many crops. The most affected crops are Gossypium hirsutum (Cotton), Medicago sativa (lucerne), Sorghum bicolor (common Natural dispersal sorghum), Triticum aestivum (wheat), Zea mays (maize) and to Spread can occur both vegetatively from cut root sections, and a lesser extent Arachis hypogaea (groundnut), Asparagus via seeds. The fruit can float, and can be dispersed over long officinalis (asparagus), Beta vulgaris var. saccharifera (sugar distances along rivers and streams, especially during floods. beet), Citrus spp. (citrus), Cucumis sativus (cucumber), Seeds are also easily and widely dispersed by agricultural Lycopersicon esculentum (tomato), Olea europaea subsp. machinery and tools, vehicles, in bales of hay and alfalfa, and europaea (olive), Prunus persica (peach), Solanum tuberosum in the dung of livestock and wild animals. Although the plants (potato), Sorghum sudanense (Sudan grass) and Vitis vinifera die back in winter, ripe fruit are retained on dead branches and (grapevine). Infestations are more serious in drylands, although may be dispersed by wind. Dried plants may also blow like irrigated croplands are also very prone to invasion, and many tumbleweeds, spreading seed along the way (Boyd et al., other horticultural and orchard crops are affected. 1982). S. elaeagnifolium has a particular pattern of spreading. In Morocco, losses of up to 64% in maize without treatment From the first point of introduction and establishment, the plant (Baye & Bouhache, 2007) and 78% in cotton have been spreads in all directions. This spreading is not continuous but reported. In Australia, wheat losses varied from 12 to 50% occurs in leaps. The space between the neighbouring colonies (Cuthbertson, 1976) according to climatic conditions and weed increases with distance from the centre (Yannitsaros et al., 1974). density, but were highest at dry, sandy sites or during low rainfall years (Heap & Carter, 1999). In the USA, sorghum and cotton yield losses under optimal moisture regimes were Agricultural practices 4Ð10% and 5Ð14%, respectively (Robinson et al., 1978), with Spread is possible by livestock and manure, irrigation water, 75% losses in cotton grown under semiarid conditions. agricultural machinery, rooted nursery plants, contaminated S. elaeagnifolium also displays allelopathic effects, espe- straw or seeds. Vehicles and tools used in agriculture, bulldozers cially in cotton fields (Californian Department for Food and and other earth-moving equipment can also spread the weed by Agriculture, 2006; Bothma, 2002). Both perennial and annual transporting both seeds and sections of root. Soil, sand and pastures are adversely affected, with pasture establishment ornamental plants can be contaminated by fragments of roots or delayed and pasture production reduced. seeds of S. elaeagnifolium (Taleb et al., 2007). As a perennial weed, S. elaeagnifolium is very difficult to control, and often disrupts tillage and harvesting practices. It can block drains and irrigation channels. Severe infestations Movement in trade could even limit the types of crop that could be successfully S. elaeagnifolium has no ornamental value and has only cultivated in the USA (Davis et al., 1945). The presence of occasionally been introduced for its aesthetic characteristics S. elaeagnifolium can lead to less effective land usage, reduced (Chalghaf et al., 2007), thus introductions worldwide appear to monetary returns, and increased production costs arising from have been unintentional. Movements of contaminated fodder control operations. are proposed as the mode of introduction into South Africa and In California, S. elaeagnifolium has been reported as a Australia, where it is suspected that multiple, rather than single, reservoir for Lettuce chlorosis virus (McLain et al., 1998) introductions have occurred. Crop seed, notably grain and which is transmitted by Bemisia tabaci. It is also recorded as a fodder crops that are contaminated by the weed, are another secondary host of several insect pests, the most important being major source of infestation (e.g. in Australia, Morocco, South Leptinotarsa decemlineata (Hare, 1990), Anthonomus eugenii Africa and California). The main crops reported to have (Patrock & Schuster, 1992), Globodera rostochiensis and contained S. elaeagnifolium are maize (Zea mays) and lucerne Globodera pallida. In Tunisia, the plant has been reported as a (Medicago sativa). potential source of Potato virus Y (PVY) propagation (Boukhris- Bouhachem, 2007). The berries of S. elaeagnifolium are toxic to livestock, Impact particularly when mature (Burrows et al., 1981). Symptoms S. elaeagnifolium has a negative impact mainly on crop include excessive salivation, nasal discharge, respiratory production but also on livestock production, on the environment complications, bloating, trembling and diarrhoea (Parsons, and on trade and international relations. 1981). The plant affects horses and causes mortality to sheep (Molnar & McKenzie, 1976) while goats are apparently unaffected (Parsons, 1981; Wassermann et al., 1988). Effects on plants By being a spring species, the life cycle of S. elaeagnifolium Environmental and social impact perfectly coincides with those of spring crops. In autumnal crops, the invasive plant is only present during the second half Although S. elaeagnifolium is primarily associated with of their life cycle. cultivated land, it may also invade adjoining areas (e.g.

© 2007 OEPP/EPPO, Bulletin OEPP/EPPO Bulletin 37, 236–245 Solanum elaeagnifolium 241 roadsides, river- and canal-sides). It may replace natural provided that dense stands be achieved and maintained. vegetation in areas of overgrazed rangeland and in heavily Although intensive browsing by cattle is reported to reduce fruit trampled areas around waterholes. However, the environmental set (Wassermann et al., 1988), the removal of all cattle from impacts are limited in comparison to the impacts on cultivated infested pasture is recommended as selective grazing increases lands. the dominance of the unpalatable S. elaeagnifolium. Agricultural land infested with S. elaeagnifolium loses The use of seed free from S. elaeagnifolium and deep plough- considerable rental and resale value. In Morocco, the value of ing at the beginning of summer are recommended as preventa- infested fields decreased by 25% (Gmira et al., 1998). In the tive measures. USA, farms have been abandoned because of infestation (Parsons, 1981). Mechanical control In winter crops, regular tillage during the preceding summer Summary of invasiveness weakens S. elaeagnifolium because of its lack of growth in S. elaeagnifolium has been introduced from North America to winter. In summer crops (e.g. cotton, sorghum), dense crops Africa, Asia, Australia, Europe and South America where it is may suppress the weed and regular tillage or clearing prevent an important weed of croplands and pastures, mostly in fruit set (Davis et al., 1945). Small infestations may be cultivated land, disturbed areas and overgrazed areas with low hand-pulled, but this should be repeated several times during rainfall. The invasiveness is aggravated by high seed production the growing season. The plant has sharp spines and gloves and an extensive root system that promotes vegetative should be worn for hand-pulling. multiplication and renders conventional control methods very Eradication action has been undertaken in the south of difficult. Other negative effects include hindering commercial France (Agence Méditerranéenne de l’Environnement, 2006). cropping activities, harbouring agricultural pests, being toxic The entire root system of the plant was taken out, and contam- to livestock and reducing land values. The plant is officially inated ground in the surroundings of the plant buried in a hole declared as a noxious weed in several countries. three metres deep. In cases of mechanical control, all parts of the plant, including the roots, have to be collected and destroyed. Considering the viability of seeds, monitoring of the Control treated area should last for at least 10 years. Control methods in Morocco are reviewed by Ameur et al., Cultural control 2007. S. elaeagnifolium is very difficult to control and it is essential to keep it out of uncontaminated areas. Any isolated plants and Chemical control small patches should be treated as soon as they appear (Parsons, 1981). In endangered areas, regular inspections during midsummer Experience in South Africa (Wassermann et al., 1988) and when plants are flowering and vigilance during harvesting are Australia (Parsons, 1981; Heap et al., 1997) has shown that recommended (Heap et al., 1997). Grain and fodder crops S. elaeagnifolium is generally very difficult to control with harvested in contaminated areas should be inspected for herbicides, including soil sterilants and nonselective chemicals. contamination. It is also recommended to check hay for None were considered effective and affordable for large S. elaeagnifolium berries before feeding it to cattle. This will infestations. Spot-spraying treatments with picloram proved prevent livestock poisoning and the introduction of seeds into effective in Australia and Greece, whereas glyphosate was uninfested areas (Californian Department for Food and unreliable and others less effective (Eleftherohorinos et al., Agriculture, 2006). In Australia, movements of livestock, 1993; Heap et al., 1997). Herbicides were considered to be mainly sheep, account for most new infestations and stock from more effective when applied during optimal moisture conditions infested areas should be quarantined for 14 days to allow all and during the ‘green berry’ stage of the weed (Stubblefield & seed to pass through the digestive tract and thus prevent further Sosebee, 1986). spread (Heap et al., 1997). Unauthorized vehicles should also Many experiments have been conducted in Morocco. be kept out of infested properties, and vehicles and machinery Zaki et al. (1995) showed a significant density and biomass should be thoroughly checked for berries and root fragments reduction of S. elaeagnifolium with the application of glyphosate and cleaned on leaving infested areas. The development of added with ammonium sulphate at the flowering and fructification S. elaeagnifolium is reduced in irrigated crops and where dense stages, followed by mowing 2, 3 or 4 weeks after treatment. The crop stands can be maintained (e.g. with lucerne). It is also combination of glyphosate and mechanical control allowed a controlled by intensive cropping in wheat-sorghum-wheat rotations reduction of density (> 92%), biomass (> 94%) and fruit and by sowing Eragrostis curvula in pastures. Viljoen & production (100%) of S. elaeagnifolium. Wassermann (2004) studied the suppression of S. elaeagnifolium Baye et al. (2007) found that systemic herbicides such as by three pasture species under dryland conditions in a field trial. glyphosate, sulfosate and amitrole have shown to be very They showed that Medicago sativa and particularly Digitaria effective and are principally recommended for nonselective eriantha have the potential to suppress S. elaeagnifolium treatments in orchards (olive, citrus, fruit trees) and fields

© 2007 OEPP/EPPO, Bulletin OEPP/EPPO Bulletin 37, 236–245 242 Data sheets on quarantine pests at postharvest (cereals, sugar beet, market gardening). These Phytosanitary measures could include that plants for planting require special application conditions and are recommended with growing medium attached originating from countries above all in cases of severe infestation. Phenoxy herbicides, where the pest is present should be grown in a growing medium imazapyr and bromacil are used for weed control on roadsides, free from the pest or should come from a pest-free area or pest- whether forested or nonforested and possibly on unused plots. free place of production for S. elaeagnifolium. Bromacil can be used in citrus orchards that are at least four Soil/growing medium (with organic matter) as a commodity years old, but only in heavily infested areas in view of its high originating from countries where the pest is present should be cost. collected in a pest-free place of production or pest-free area for S. elaeagnifolium. Seeds of Gossypium spp., Hordeum indicum, Medicago Biological control sativa, Nicotiana tabacum, Sesamum indicum, Sorghum S. elaeagnifolium supports a diverse insect herbivorous fauna in bicolor, Triticum spp., or Zea mays from countries where the its area of origin (Goeden, 1971), some of which have been pest occurs should be cleaned or should come from a pest-free tried as biological control agents notably in South Africa area or pest-free place of production for S. elaeagnifolium. (Olckers & Zimmermann, 1991) and Australia (Wapshere, Consignments of grain (Hordeum spp., Sesamum indicum, 1988). Two leaf-feeding beetles, Leptinotarsa texana and Sorghum bicolor, Triticum spp, Zea mays) from countries where Leptinotarsa defecta, are established in South Africa following the pest occurs should be cleaned, or should come from a pest- release in 1992, though only L. texana causes considerable free area or pest-free place of production for S. elaeagnifolium. damage, by reducing growth and fruit production (Hoffmann Cleaning or disinfection of imported machinery or vehicles et al., 1998; Olckers et al., 1999). Morocco has more recently from countries where the pest occurs is recommended. Public- expressed an interest in importing these biological control ity to enhance public awareness on pest risks is a recommended agents (Klein, 2001). Sforza and Jones (2007) state that measure as S. elaeagnifolium can be a contaminant on foot- biological and impact studies of Leptinotarsa spp. in Europe wear. Use of clean containers and packaging material is also should be conducted. The native leaf-galling nematode recommended. Ditylenchus phyllobius has been used with some success in the USA (Northam & Orr, 1982). It has become established in India, probably after having been introduced with the plant. References It was considered as a biological control agent in South Africa, Agence Méditerranéenne de l’Environnement (2006) Opération but was not released due to doubts about its host specificity d’éradication de la morelle jaune sur la commune de Châteauneuf- (Olckers & Zimmermann, 1991). A foliar nematode, Orrina les-Martigues, Languedoc-Roussillon (FR). http://www.ame-lr.org/plantes- phyllobia, which causes leaf and stem galling has also been envahissantes/solanum_cr.pdf [accessed on 7 November 2006] studied (Roche, 1991). Nevertheless, biological control can Ameur A, Baye Y, Bouhache M & Taleb A (2007) Revue des moyens de lutte contre la morelle jaune (Solanum elaeagnifolium Cav.) au Maroc. only be considered as one component of an integrated Bulletin OEPP/EPPO Bulletin 37, 137Ð144. management plan, to be used in conjunction with specific Baye Y, Ameur A, Bouhache M & Taleb A (2007) Stratégie de lutte management practices. chimique contre la morelle jaune (Solanum elaeagnifolium Cav.) au Maroc. Bulletin OEPP/EPPO Bulletin 37, 145Ð152. Baye Y & Bouhache M (2007) Etude de la compétition entre la morelle Regulatory status jaune (Solanum elaeagnifolium Cav.) et le maïs de printemps (Zea mays S. elaeagnifolium has accidentally been introduced into several L.) Bulletin OEPP/EPPO Bulletin 37, 129Ð131. Bothma A (2002) Alleopathic potential of silverleaf nightshade (Solanum countries via contaminated fodder crops. Consignments of elaeagnifolium Cav.) MSc (Agric) Horticulture. University of Pretoria, seeds, containers and packing material, plants for planting with Pretoria (ZA). http://upetd.up.ac.za/thesis/available/etd-10072005Ð121704 soil, soil as a consignment, soil as a contaminant, and livestock [accessed on 7 November 2006] also present a high phytosanitary risk for the countries that Boukhris-Bouhachem S, Hullé M, Rouzé-Jouan J, Glais L & Kerlan C import these products from infested countries. S. elaeagnifolium (2007) Solanum elaeagnifolium, a potential source of Potato virus Y is declared invasive in several countries, including Morocco (PVY) propagation. Bulletin OEPP/EPPO Bulletin 37, 125Ð131. Boyd JW & Murray DS (1982) Growth and development of silverleaf where it is considered as the country’s most noxious weed nightshade (Solanum elaeagnifolium). Weed Science 30, 238Ð243. (Taleb, 2006) and is under official control. In Belarus, Russia Burrows GE, Tyrl RJ & Edwards WC (1981) Toxic plants of Oklahoma Ð and Ukraine where it is a quarantine pest, grain consignments thornapples and nightshades. Journal of the Oklahoma Veterinary and are required to be free from its seeds. This plant is also included Medical Association 23, 106Ð109. in lists of plants controlled under noxious weed legislation in California Department for Food and Agriculture (2006) California Australia, South Africa and approximately 20 states of the USA (US). http://www.cdfa.ca.gov/phpps/ipc/weedinfo/solanum-carolinense. (USDA-NRCS, 2005). Moreover, the sale of contaminated htm [accessed on 23 April 2007] Chalghaf E, Aissa M, Mellassi H & Mekki M (2007) Maîtrise de la propa- agricultural products with Solanum elaeagnifolium is prohibited gation de la morelle jaune (Solanum elaeagnifolium Cav.) dans le in South Africa (Wassermann et al., 1988). gouvernorat de Kairouan (Tunisie). 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