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   Ligustrum robustum (tree, shrub)  français     
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         Management Information

    Physical: Small plants may be hand pulled; older individuals need to be dug out. Plants should be pulled as soon as they are large enough to grasp but before they produce seeds. Seedlings are best pulled after a rain when the soil is loose. Larger stems, up to 6cm (2.5 in), can be removed using a Weed Wrench or similar uprooting tools. The entire root must be removed since broken fragments may resprout. Alternatively, mowing or cutting will control, but not eradicate privet. It is appropriate for small populations or environmentally sensitive areas. Stems should be cut at least once per growing season as close to ground level as possible (PIER, 2003; SE-EPPC, 2003).

    Chemical: There are three forms of applying chemical treatment to privet: (i) the foliar spray method can be used for expansive areas of privet where risk to non-target species is minimal. Air temperature should be above 18°C to ensure absorption of herbicide. Apply a 2% solution of glyphosate and water plus a 0.5% non-ionic surfactant to thoroughly wet all leaves; use a low spray pressure and coarse spray pattern to reduce spray-drift as glyphosate is non-selective. Alternatively, apply a 2% solution of triclopyr and water plus a 0.5% non-ionic surfactant, to thoroughly wet all leaves; use a low pressure and coarse spray pattern to reduce spray-drift damage to non-target species. Triclopyr can be used without damage to grasses. Metsulfuron is also effective when sprayed on wet foliage (at the rate of 5 grams per 10 liters of water). (ii) the cut stump method can be used to treat individual bushes or in environmentally sensitive areas. Horizontally cut privet stems at (or near) ground level. Immediately apply a 25% solution of glyphosate (or triclopyr) and water to the cut stump making sure to cover the entire surface, and (iii) the basal bark method involves applying a mix of 25% triclopyr and 75% horticultural oil to the basal parts of the shrub to a height of 30-38cm (12-15 in). Stems of less than 1.25cm in diameter are susceptible to this method (larger stems should be notched or frilled). Thorough wetting is necessary; spray until run-off is noticeable at the ground line (SE-EPPC, 2003; PIER, 2003).

    Biological: The Réunion Island Regional Council (in collaboration with CABI Bioscience) began a research into the possibility of biological control of L. robustum. They indentified several species including a moth (Epiplema albida), Dermorhytis ornatissima, D. lewis and one Hyphasis species; further testing of E. albida is planned for 2005 (CABI Bioscience, 2002; PIER, 2003; Sakalsooriya et al. 2002; 2003; Shaw, R., pers. comm., 2004). français     

         Location Specific Management Information
    Integrated management: Conservation Mangaement Areas have been established in Mauritius to protect native fauna from displacement by more competitive alien weed species (such as L. robustum and the strawberry guava, Psidium cattleianum). Since 1951 sixteen Nature Reserves have been set up to preserve native ecosystems. The reserves cover 2.5 % of the island and range from 1.5 ha to 3,611 ha in size (the Perrier Nature Reserve and Macchabee-Bel Ombre Nature Reserve, respectively). In 1994 under the Wildlife and National Parks Act, 1993 the Macchabee-Bel Ombre and Combo nature reserves were combined to form the 6,754 ha Black River Gorges National Park (Mungroo and Tezzo, 1996). Nine intensively managed vegetation plots, known as Conservation Management Areas (CMAs), have been established. CMAs cover a total of 44 ha and range from 1.5 ha to 19 ha in size, the largest of which is located within the National Park. The CMAs are fenced (a low stone wall to keep out deer and pigs) and weeds are manually uprooted four times a year. Control of alien invasive plant species in the CMAs has proved promising. Endangered plants have been found growing in these areas and regeneration of endemic plants is occuring, providing a better habitat for endemic endangered birds such as the pink pigeon and the echo parakeet (Mungroo and Tezoo, 1996). Manually uprooting weeds is labour intensive and cannot be applied to large areas.In 1996, a a biodiversity assessment of a 6 ha plot (within the 25 ha fenced Brise Fer CMA) was implemented by the Mauritian Wildlife Foundation (MWF) and the Government of Mauritius. Trials on the chemical control of exotic weeds were initiated (Mungroo and Tezzo, 1996). Results from chemical control trials in the Brise Fer CMA (undertaken during six weeks in 1993) were unpromising: L. robustum and P. cattleianum (strawberry guava) were cut with rangers knife at about waist height and herbicide was applied to the stump by small brush at a concentration of 10% (one part Garlon to 9 parts water). More recent trials with Garlon (at the manufacturers concentration) on stumps about 20 cm from the ground has proven to be more effective in controlling the exotic weeds. As Garlon is expensive trials with other herbicides are currently underway (Mungroo and Tezzo, 1996).
    Reunion (La Reunion)
    Conservation of the primary forest of Réunion depends on the setting up of an education programme to increase public awareness of the affect of introduced plants on island ecosystems. Local land managers need to be taught the latest control techniques. Réunion has recently set up a quarantine facility. L. robustum produces much less fruit in its native range in Sri Lanka than it does on Réunion, suggesting a lack of natural predators might be facilitating its spread into the native forests on the Mascarene islands. Biological control has not been used against any members of the Oleaceae family (of which L. robustum is a member) previously. On behalf of the Regional Council of Réunion (and with funding from the EU) the following organisations collaborated in a research effort to investigate the possibility of biological control of L. robustum between 1997 and 2001: CABI (Switzerland), CABI (UK), the Institute of Biological Control (China), the University of Réunion (France), the Postgraduate Institute of Agriculture (Sri Lanka) and the University of St. Andrews (UK) . In 1998 they identified several insects antagonistic to L. robustum in Sri Lanka: several chrysomelid beetles, defoliating Lepidoptern (of the families Geometridae, Pyralidae, Epiplemidae and Noctuidae) and an inflorescence feeding pentatomid. Fungi belonging mainly to the Dothideales, including Mycosphaerella and Guignardia, were found living hemibiotrophically on leaf tissue (and causing premature senescence). The research concluded that few insects or pathogens were identified as suitable biological control agents for L. robustum but the most promising included a moth (Epiplema albida) and a European Thedgonia species. According to a recent project update final testing for the use of the moth as a biological control agent may occur in 2005. The Thedgonia species has since been reported to have introduced onto the island accidentally (probably on another ornamental privet) and its impact has been targeted for assessment (Lavergne, C., pers. comm., in CABI Bioscience, 1998; CABI Bioscience, 2002; Shaw, R., pers. comm., 2004).

         Management Resources/Links

    1. CABI Bioscience, 1998. Project Summary Report: Biological Control of Wild Privet (Ligustrum robustum) for La Réunion.
            Summary: Initial survey of possible biological control options for L. robustum. (Not presently available online).
    5. Food and Agriculture Organisation of the United Nations (FAO), 1995. Conservation And Sustainable Utilization of Plant Genetic Resources in Indian Ocean Islands, FAO International Technical Conference on Plant Genetic Resources (Sub-Regional Synthesis Report: Annex 1 of the Report of the Sub-Regional Preparatory Meeting for Eastern Africa and Indian Ocean Islands). Food and Agriculture Organisation of the United Nations: Nairobi, Kenya.
            Summary: A detailed overview of the agricultural resources, floral biodiversity, and the plant genetic resources of the five Indian Ocean Island Countries (Madagascar, the Seychelles archipelago, the Federal Islamic Republic of Comoros, the Independent Republic of Mauritius, which includes Rodrigues island, and the French Departement, Réunion island).
    7. IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
            Summary: The IUCN Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been globally evaluated using the IUCN Red List Categories and Criteria. This system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those taxa that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable). The IUCN Red List also includes information on taxa that are categorized as Extinct or Extinct in the Wild; on taxa that cannot be evaluated because of insufficient information (i.e. are Data Deficient); and on taxa that are either close to meeting the threatened thresholds or that would be threatened were it not for an ongoing taxon-specific conservation programme (i.e. are Near Threatened).
    Available from: [Accessed 25 May 2011]
    8. Kueffer, C. and Mauremootoo, J., 2004. Case Studies on the Status of Invasive Woody Plant Species in the Western Indian Ocean. 3. Mauritius (Islands of Mauritius and Rodrigues). Forest Health & Biosecurity Working Papers FBS/4-3E. Forestry Department, Food and Agriculture Organization of the United Nations, Rome, Italy.
    9. Lavergne, C. and Shaw, R. 1999 The Invasive Behaviour and Biological Control of Ligustrum robustum subsp. walkeri on the Mascarene Island of La Reunion. ALIENS. IUCN Publication. pp 13.
    11. Maunder, M., Page, W., Mauremootoo, J., Payendee, R., Mungroo, Y., Maljkovic, A., Vericel, C. and Lyte, B. 2002. The Decline and Conservation Management of the Threatened Endemic Palms of the Mascarene Islands, Oryx 36(1): 56 - 65.
            Summary: The status of threatened palm species in the Mascarene islands.
    12. Mungroo, Y. and Tezzo, K. 1996. Restoration of Highly Degraded and Threatened Native Forest in Mauritius. , Contribution to UNEP/World Bank Africa Forest Policy Forum, Nairobi, Kenya.
    15. Safford, R.J. and Jones, C.G. 1998. Strategies for Land-Bird Conservation on Mauritius, Conservation Biology 12(1): 169 - 176.
            Summary: The benefits of enhancing mainland habitats by establishing exotic plantations (to provide refuges for birds from mammalian predators) is discussed.
    16. Sakalasooriya, M.B., Wijegunasekara H.N.P., Marambe B. and Shaw. R. 2000. Biological Control of Ligustrum robustum in the Island of La Réunion, Tropical Agricultural Research 12: 205 - 216.
            Summary: Identification of natural enemies of L. robustum in its native region.
    17. Sakalasooriya, M.B., Wijegunasekara H.N.P., Marambe B. and Shaw. R. 2001. Screening of Potential Biocontrol Agents for Ligustrum robustum spp. walkeri, for Possible Release in the Island of La Réunion, Tropical Agricultural Research 13:215 - 225.
            Summary: Information on potential biocontrol agents for L. robustum.
    19. Shaw, R., Cock, M.J., Evans, H.C., Gassman, A., Wheeler, S., Djeddour, D., Milne, R. and Sakalasooriya, M.B.. 2000. Biological Control of L. robustum subsp. walkeri on the Island of La Réunion (end year report). CABI-Bioscience: UK.
            Summary: Progress report on the L. robustum biocontrol project.
    20. Shaw, R.H. 2004. Personal communication (email). CABI Bioscience, Silwood Park, Ascot, Berkshire, SL5 7TA, England.
            Summary: A email giving an update of the CABI bioscience biological control project for Réunion Island was recieved.

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ISSG Landcare Research NBII IUCN University of Auckland