|June 2006. The dangers of Jatropha curcas as a problematic weed in many parts of the world were noted. Now it is being promoted for biodiesel. In India, there is a plan to raise it in over 84,000 ha. Information about its potential harm can be seen at: http://ecoport.org/ep?SearchType=earticleView&earticleId=877&page=-2
What are the alternatives in India? One possibility is a near relative, Karanj (Pongamia pinnata). A discussion on its merits can be found at: http://ecoport.org/ep?SearchType=earticleView&earticleId=845&page=-2. Utilization of weeds for biodiesel is a good concept, but large scale plantation of any weed, particularly any weed with well-known invasive properties is not.
A request has also been made to import seeds into St Lucia with the intention of establishing a biofuel operation. The plant is not present in St. Lucia.
Information on the risk of Jatropha can be found at the PIER website (and included here is a risk assessment prepared for Australia. In Western Australia it is listed as a quarantine weed. www.hear.org/Pier/species/jatropha_curcas.htm.
In a later posting, two articles showing how badly Jatropha is performing in India. Insects and diseases are causing damage.
A Weed Risk Assement form was sent to PestNet by the CABI Southeast & East Asia Senior Scientist, and it was suggested that if members were planning to import the species, then they should use it to make an assessmen of its invasiveness. A response was received from Zambia, who considered that it had the potentail to become naturalised and invasavie under local conditions.
Oct 2008. More questions were asked about Jatropha; again they revolved about it being invasive. These are summaries from several countries.
Samoa also asked about the weed status of this plant after a case study (no reference) suggested that it was not “self-propagating”. There was confusion as J gossypifolia has been banned in Western Australia because it is invasive.
In reply, it was said that the first comment is clearly false, For a species to be self propagating it should be able to produce viable seed, or be able to propagate vegetatively. Jatropha curcas is clearly capable of both and as it is the seed that is harvested any claims that the plant is not self propagating is clearly the result of a poorly informed mind. This species is often used to create living hedges by placing branches into shallow trenches which then strike creating dense woody hedges, or living fences. These can then, if not routinely maintained, get out of control and become dense thick infestations.
The second comment is true, Both Jatropha gossypifolia and J curcas are prohibited species in Western Australia. J curcas has also been eradicated from the Northern Territory only recently because of concern for its invasive potential.
In Burma, Shan State, Jurcas is used as hedges to fence animals, and there are many thousands of kilometres of the plant, but as far one member was aware it had not become a problem. It sets seeds but these do not germinate to form thickets. There have been reports of poisonng in Burma, but the link to the news no longer exists: www.pestnet.org/Summaries/Pests/PestsEntities/Weeds/Jatrophaisitharmfultochildren/tabid/3056/Default. But it is also widely known as a traditional medicine in parts of Burma, so the true situation with regards poisoning remains unknown.
Jatropha curacas has naturalised as a weed in a number of Pacific island countries (Fiji, PNG, Tonga, Samoa, Vanuatu – the photos are from Santo, Vanuatu). It is listed in the Global Compendium of Weeds by RP Randall (2002) as “Weed, Quarantine Weed, Noxiuous Weed, Naturalised, Introduced, Environmental Weed, Cultivation”. Further details are in www.hear.org/pier. Also, see evidence of escape from living fences in Tonga in: James C Space, Tim Flynn (2001) Report to the Kingdom of Tonga on Invasive Plant Species of Environmental Concern. USDA Forest Service, Pacific Southwest Research Station, Institute of Pacific Islands Forestry, Honolulu, Hawai???i, USA.
Jatropha gossypifolia is a serious invasive weed in drier areas in New Caledonia, and less so in southern PNG and eastern Australia.
In Laos, Jatropha is being promoted because the oil from it can be easily utilzed by diesel engines, which is not true for cassava. In Laos, it is almost all mountains. So putting cassava on a hill is simply not something that can be done.
Farmers do actively manage it in fences, and it fhas not become a weed, but very important for livestock. There are a lot of companies wanting to expand the production of this plant across the country, which has met with a lot of criticism, and rightfully so. However, if production could be increased by constructioning more hedgerows, that would be useful as it contributes to better soil conservation and livestock management. In India, cattle have been put into Jatropha plantations with poor results:
Dead Jatropha plants collected in one place
The case against using Japtropha in India as a biofuel, can be found at:
And there are other references in the links to the PestNet list below (see particularly:
But in Kerala, Jatropha is used as a living fence, and the plant as a traditional medicine.
In Bangladesh, Jatropha is a common hedge plant in the Bengal Basin. People use its twigs as a toothbrush in the morning, chewing and softening the wood for brushing the teeth, spitting out the juice and hard parts. There was no knowledge of poisoning reported. It is an important living hedge, protecting crops from grazing animals and it can be a very useful energy source. It is being actively promoted.
In Malaysia, there is evidence that the plant is not invasive, and there has not been any evidence for its toxicity. The major challenges, however, are the inconvenience and intensive labor requirements (and thus high costs) due to the manual handling of fruits during harvest and the dehusking (machines on test now) for seeds. The concern is more with the agronomic and economic viability of the crop as a biofuel.
See also PestNet>Summaries>Crops>Plantation crops>Jatropha>Is it harmful to children?
In summary, It appears that Jatropha has many potential uses, and if managed properly is unlikely to be a risk either to the environment or to human beings. But a proper risk assessment is needed where it is not already present. Where it is present, and where it is being used for commercial purposes and even where it is not, making people aware of its potential danger would seem to be a sensible thing to do.