July 2010. A ProMED-mail post on an outbreak of taro leaf blight in Cameroon produced a lot of comment from members.
The experiences of the Pacific after the outbreak of the disease in Samoa in 1993 are relevant. At first, spraying was advocated, as well as cultural practises, such as cutting off diseased leaves, but neither worked well. Fungicides were too expensive except for the wealthiest farmers, and leaf pruning proved futile in the high Samoan rainfall. The only chance of overcoming the problem was to breed for resistance. This was done in Samoa and also in Papua New Guinea, but it took a few years to get donor support for the project. TaroGen began in 1998.
Today, the disease is no longer a threat to taro production. Recently (September 2010) Samoa has started to export taro to New Zealand once again, challenging the supremacy of Fiji, which took over the trade after the disease struck in Samoa.
Cameroons would do well to study the events that occurred in Samoa after the outbreak, which have been documented in several papers. The country might also wish to note some of the comments from PestNet members that are provided below.
There was surprise that donor support could be not obtained; there was also a mention of the crops that farmers grew in Samoa to substitute for the loss of taro. Furthermore, there are pathogen-indexed plants available in tissue culture from the SPC, and the only issue to be resolved is that of IP. Presumably, any varieties sent to Cameroons would be done under the standard MTA formulated in conjunction with the International Treaty on Genetic Resources for Food and Agriculture.
Later (November 2010), there was a report in allAfrica.com that the National Root Croops Research Institute, Umuahia, Abia State, Nigeria was to intensify research into taro leaf blight: allafrica.com/stories/201012131161.html. It mentioned that Togo and Ghana were also affected, and that Cameroons had written to Nigeria.
In response Pestnet members suggested to write to the African countries to offer assistance. Perhaps MAF/USP SAmoa could take the leaf, assisted by SPC CePACT. SPC could provide assistance through assistance to Nigeria and other countries via the FAO (Secretariat of the International Plant Protection Convention) and the IAPC (Inter-African Phytosanitary Council).
There was also a suggestion to use the methods of the Dominican Republic to bring the disease under control. In this case, production was moved to an area with less rainfall, drip irrigation was used, and resistant taros introduced.
An EU-funded project to create a global taro network is soon to begin, and it is likely that assistance will be offerend under that project as some of the affected countries (Ghana and Nigeria) are members. As the project is coordinated by SPC, help from the pacific region can be facilitated that way.
Later, information and comments relating to taro leaf blight:
(January 2011), it was asked whether cocoyam was Xanthosoma or Colocasia; in fact, it is both. They are nurse crops for cocoa.
(February 2011), an article in AlertNet (http://www.trust.org/alertnet/news/cameroon-creates-national-climate-change-observatory) about the creation of the National Observatory on Climate Change by Cameroon’s government. This will monitor the effects of climate change on the country’s people, agriculture and ecosystems, guiding work on climate action. The outbreak of taro leaf blight is thought to be caused by changes in the weather pattern, or perhaps worsened by it.
(February 2011), another article on the situation in Cameroon (panos.org.uk/features/cameroons-changing-weather-linked-to-crop-disease/) on a website, Panos London Illuminating Voices. The article is entitled: Cameroon’s changing weather linked to crop disease. The article says that scientists have linked dust which has fallen on the leaves with the disease. There was also a suggestion that the outbreak is linked to climate change.
[Editor] The idea that dust blown to Cameroon brought the disease is understandable. However, the spores last only a few hours, and are unlikely to have come with dust; more likely they came with wind and rain from neighbouring countries.