Prosopis spp. (tree, shrub)
Preventative measures: A Risk assessment of Prosopis spp. for Australia was prepared by Pacific Island Ecosystems at Risk (PIER) using the Australian risk assessment system (Pheloung, 1995). The result is a score of 20 and a recommendation of: reject the plant for import (Australia) or species likely to be a pest (Pacific).
Eradication of Prosopis has proven to be extremely difficult or impossible. Better management of Prosopis, different land use strategies and the exploitation of Prosopis as a resource may reduce its invasiveness in some regions as well as improving local economies (Pasiecznik 2002). Examples of better management include: 1) Stand conversion and improvement- Weedy stands thinned to 100-400 trees per hectare, in stages. Broad strips cleared and cut stumps are removed manually/mechanically, treated by stripping the bark or treated with used motor oil/triclopyr and diesel mixture. Animals may re-enter immediately as these chemicals have little mammalian toxicity. Selected trees in the remaining rows are pruned to single stems at final spacings of 5 by 5 metres to 10 by 10 metres. The cost of the operation should be at least covered by the charcoal, wood chips and small timber obtained from operation; 2) Pruning appears to be the single most important technique in improving tree and understorey yields. Weedy shrubs are turned into valuable, productive trees by removal of side branches. Regularly pruned trees are found to have smaller root systems, use soil water more efficiently and compete less with neighbouring crops and grasses. Stands can be improved by introducing thornless or high yielding varieties or by grafting or interplanting; 3) Prevention- Prosopis seedlings rarely establishing under mature trees or in tall grass. Re-invasion can be minimised by maintaining a high-pruned tree canopy and improved understorey management. A reduction in stocking rates, for example, can encourage good grass cover, preventing Prosopis seedling establishment. Destroying seed, by the collection and use of pods for stall feeding or processing, reduces re-invasion. A change of livestock from cattle to sheep or pigs (which kill most to all of seeds ingested) also limits Prosopis spread
The Best Practice Manual Mesquite Control and management options for mesquite (Prosopis spp.) in Australia aims to provide the most current information on mesquite in Australia. The control and management options presented in this manual are the combined results of years of trials carried out by many dedicated researchers, landholders, herbicide companies, government officers, landcare groups and others. As mesquite species respond differently to control methods, the most effective method or combination of methods will vary depending on the size, density and species of mesquite present. The manual includes a 'mesquite control tool box'. Included also are a number of case studies to demonstrate best practice.
Location Specific Management Information
Small eradication programmes (based on herbicide use and mechanical removal) have been implemented in Argentina in order to try and eradicate Prosopis. Some are effective for a short time but the Prosopis generally returns. Nevertheless, governments continue to implement new programmes, now aiming to control rather than eradicate invasions, using the same techniques (Pasiecznik 2002a).
Most mature seed bearing trees across Australia have been killed within the past decade. To eradicate this species, however, monitoring and treatment will be required at treated sites for up to fifty years to control seedlings. A “Weeds of National Significance” strategic plan was produced in 2000 to address these issues, with the aim of confining and eventually eradicating all mesquite spp and hybrids from Australia. The plan outlined four main aims: (i) to coordinate mesquite management at a national level, (ii) to confine all core infestations and subject them to long-term management, leading to ultimate eradication, (iii) to isolate and eradicate all scattered infestations and (iv) to prevent mesquite spp from spreading. Although control methods generally do not discriminate between Prosopis species the strategy recognises that the potential distribution of the various species differs and some species may be easier to control (for example, P. pallida is more susceptible to fire and mechanical control). ‘Core infestation areas’ highlighted in the strategy ‘Mardie Station’ (Western Australia), the Hughenden area and ‘Comongin’ (Queensland) and Broken Hill/Milparinka (New South Wales).
Some forty other Prosopis species could be introduced around Australia. Eight species are considered to be potential pests. The Australian Quarantine and Inspection Service (AQIS) currently prohibit the importation of 8 Prosopis species, whilst also maintaining a general prohibition on the genus entering Australia.
Tall dense infestations may require mechanical control, followed by fire and foliar
spraying of seedlings. Isolated multi-stemmed plants may require foliar sprays
and they are generally more difficult to treat. Isolated single-stemmed plants (P. pallida) can be treated using basal bark or cut-stump techniques.
Prosopis species have declared status in 5 states and 1 territory (Queensland, Western Australia, New South Wales, South Australia, Victoria, Northern Territory).
Seed-feeding beetles, Algarobius bottimeri and A. prosopis are presently established in low densities but currently only remove a small fraction of the seeds. Evippe sp. (a leaf-tying moth) and Prosopidopsylla flava (a sap-sucking psyllid) show promise. In lab tests both Evippe and P. flava performed equally well on Australian mesquites. Recently the moth caused large-scale defoliation at Mardie Station, WA (Agriculture & Resource Management Council of Australia & New Zealand, 2000).
P. juliflora has become an aggressive weed in several states. Ecologists have become alarmed by the invasion of grasslands, protected forests and nature reserves. The invasion of irrigation channels and arable land has affected the agricultural community, landowners and large, commercial farms. In Gujarat, Rajasthan, Haryana and Tamil Nadu eradication programmes have begun.
On the other hand, P. juliflora is almost unsurpassable as a fuel in India. Many rural people completely rely on it to cook their meals. Prosopis, sustains rural areas as it is often the only source of fuel, small roundwood and dry season fodder, and provides the only income for many families. It is so important to impoverished groups of society, including the landless, small farmers and artisans, that it has been called the tree of the poor. Increasing Prosopis knowledge among these groups will enable and empower them to manage this important resource, improving local economies and encouraging Prosopis management in the regions where it is most widely used (ie: in rural areas) (Pasiecznik 2002b).
A series of training courses funded by the DFID on the management and utilisation of P. juliflora was held in 2001. It passed valuable Prosopis knowledge on to the participants, who included foresters, farmers and NGOs and private business representatives. The information was sourced from experts in Argentina, Mexico and Peru (where people have developed local economies based Prosopis juliflora and its products). The following are some of the policy recommendations that were collated during the conference:
- State Governments should purchase Prosopis pod flour as subsidised livestock fodder in drought as it is cheaper and more nutritious than the alternatives, and its purchase will generate employment, improving rural economies.
- Promote the collection of data on the spread and present use of P. juliflora in all states of India.
- Joint management of roadside trees, with the Forestry Department paying villagers day rates to thin, single and prune, generating employment and training villagers.
- Encourage State Forestry Departments and State Forest Development Corporations (SFDC) to promote and market Prosopis tree products.
- Establish independent funds for credit for commercial processing, as lending institutions appear unwilling to provide credit to Prosopis-based business.
- Promote assured markets for Prosopis products through government intervention, positive ‘press’ and pressure on private enterprise to establish industries for tree product processing.
- Education in the villages, especially of women and illiterates, on the value of Prosopis tree products should become an integral part of all rural extension activities.
- Cheap, simple improved kilns for charcoal production, small scale pod processors, and suitable saw-milling technologies for processing Prosopis wood for furniture making developed.
Small eradication programmes (based on herbicide use and mechanical removal) have been implemented in Pakistan in order to try and eradicate Prosopis. Some are effective for a short time but the Prosopis generally returns. Nevertheless, governments continue to implement new programmes, now aiming to control rather than eradicate invasions, using the same techniques (Pasiecznik 2002a).
In South Africa, where the seed-feeding bruchid beetles Neltumius arizonensis, Algarobius prosopis and A. bottimeri have been introduced from North America (Pasiecznik 2002a).
For over 50 years, small eradication programmes (based on herbicide use and mechanical removal) have been implemented in Sudan in order to try and eradicate Prosopis. Even children have been trained to uproot Prosopis. Control is effective for a short time but the Prosopis generally returns. Nevertheless, governments continue to implement new programmes, now aiming to control rather than eradicate invasions, using the same techniques (Pasiecznik 1999 2002a).
United States (USA)
For over 50 years, a major eradication programme in the USA has been employed to try and eradicate Prosopis with a combination of herbicide use and mechanical removal. Millions of dollars have been spent but still no cost effective solution has been found as the Prosopis generally returns. Nevertheless, governments continue to implement new programmes, now aiming to control rather than eradicate invasions, using the same techniques (Pasiecznik 2002a).
2. Australian Weeds Committee, 2008. Weeds of National Significance. Mesquite
Summary: This site provides information on the strategy for the management of Mesquite (Prosopis). Documents available for download include the strategy, Mesquite control manual, brochures, posters and current and potential distribution maps.
Available from: http://www.weeds.org.au/WoNS/mesquite/ [Accessed 23 October 2008]
4. IUCN/SSC Invasive Species Specialist Group (ISSG)., 2010. A Compilation of Information Sources for Conservation Managers.
Summary: This compilation of information sources can be sorted on keywords for example: Baits & Lures, Non Target Species, Eradication, Monitoring, Risk Assessment, Weeds, Herbicides etc. This compilation is at present in Excel format, this will be web-enabled as a searchable database shortly. This version of the database has been developed by the IUCN SSC ISSG as part of an Overseas Territories Environmental Programme funded project XOT603 in partnership with the Cayman Islands Government - Department of Environment. The compilation is a work under progress, the ISSG will manage, maintain and enhance the database with current and newly published information, reports, journal articles etc.
5. Mwangi, Esther & Brent Swallow., 2008. Prosopis juliflora Invasion and Rural Livelihoods in the Lake Baringo Area of Kenya. Conservation & Society Year : 2008, Volume : 6 Issue : 2 Page : 130-140
Summary: Global concern about deforestation caused by fuelwood shortages prompted the introduction of Prosopis juliflora to many tropical areas in the 1970s and 1980s. P. juliflora is a hardy nitrogen-fixing tree that is now recognised as one of the world's most invasive alien species. The introduction and subsequent invasion of P. juliflora in the Lake Baringo area of Kenya has attracted national media attention and contradictory responses from responsible agencies. This paper presents an assessment of the livelihood effects, costs of control and local perceptions on P. juliflora of rural residents in the Lake Baringo area. Unlike some other parts of the world where it had been introduced, few of the potential benefits of P. juliflora have been captured and very few people realise the net benefits in places where the invasion is most advanced. Strong local support for eradication and replacement appears to be well justified. Sustainable utilisation will require considerable investment and institutional innovation
8. Pasiecznik, N. 2002. Prosopis (Mesquite, Algarrobo): Invasive Weed or Valuable Forest Resource?. Forestry Research Programme HDRA (Henry Doubleday Research Association).
9. Zimmerman H. 2003. Pers. Comm. (email)
Summary: An email describing the two-fold nature of the impact of Prosopis spp. in a global context, as well as highlighting the problem of Prosopis species-specific classification (due to high hybridisation levels in mixed-Prosopis spp. communities).
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