Cocoyam, a generic term for both Xanthosoma and Colocasia, is a traditional staple root crop in many developing countries in Africa, Asia and the Pacific. Despite its nutritional qualities and its importance to the livelihoods of many smallholder farmers, this crop has received little attention in research. To tap into it potential, RTB has recently commissioned a study to help develop an action plan aimed at addressing key needs in cocoyam research in West and Central Africa.

“Cocoyam is not only very important for the livelihood of poor farmers, it also serves as a food security crop for these farmers across many countries in West and Central Africa, particularly in Nigeria, Ghana and Cameroon,” says Joseph Onyeka, the author of the study, a senior plant pathologist and the coordinator of Farming Systems Research Programme (FSRP) at the National Root Crops Research Institute (NRCRI), Umudike, Nigeria. “Farmers depend on cocoyam as a major staple food during critical periods such as conflict, famine and natural disasters,” Onyeka continues, mentioning the recent case of the Democratic Republic of Congo, where farmers resorted to cocoyam in order to mitigate food insecurity after many banana plantations were lost to the devastating Xanthomonas wilt disease (BXW).

In West and Central Africa cocoyam is often associated with low income and socio-economic status, and its production system is largely an informal activity. As a result, cocoyam is usually considered a “poor man’s crop”, or a “woman’s crop”, as most producers are female. In Ghana, a woman who does not have a cocoyam farm might as well be qualified as a non-farmer, Onyeka discovered. Following an old eastern Nigeria tradition, female farmers normally have cocoyam farms that sons-in-law are expected to help with. Women are the custodians of cocoyam farming in most African countries, thus improving cocoyam production should have a direct impact on the most economically vulnerable groups.

A typical local market of cocoyams in Nigeria (Kikuno/IITA)


 “Cocoyam has better nutritional qualities than other root and tuber crops such as cassava and yam, with higher protein, vitamin and mineral content. A versatile staple, cocoyam can also be used as weaning food, while the leaves can be cooked as vegetable. However, these benefits, along with the wide adaptability of the crop and its role in the economy and livelihood of millions of rural poor, have been under-estimated, under-reported, and therefore poorly appreciated,” explains Onyeka. “Those who depend heavily on the crop for survival – the most vulnerable groups – have neither the resources nor the voice to influence its future. It is the responsibility of scientists and policymakers to change this situation through strategic interventions.”

Tapping the potential of cocoyam as a food and cash crop implies identifying and addressing many constraints, including two important diseases that affect cocoyam production in West and Central Africa: Cocoyam root rot disease (CRRD) and Taro leaf blight (TLB). These diseases impacts move beyond one season of damage because cocoyam’s vegetative mode of propagation supports transmission of diseases from one generation to the next. The recycling of infected planting materials from farmers’ fields leads to reduced yield and build-up of diseases. A recent outbreak of TLB in many countries of West and Central Africa has drastically reduced the productivity of C. esculenta spp in the region. Both CRRD and TLB are of great concern to cocoyam farmers in the region because of their potential to cause total crop failure, thereby posing a great threat to food security. In addition to constituting a threat to income and food security, both diseases have the potential of depleting the diversity in the already narrow genetic base of these crops due to the high susceptibility of most farmers’ cultivars.

Cocoyam leaves for sale in Cameroon (Asiedu/IITA)


FAO has declared that to feed an additional 2.3 billion people by 2050, there should be a 70% increase in agriculture production on existing farm land, Onyeka points out. This is not the case in western Africa, where increasing cocoyam production is done by farming more land rather than increasing crop yields. At the same time the current yield of cocoyam in WCA is far below its potential yield, Onyeka discovered in his study.

To address these different constraints to productivity, he suggests a series of interventions, including:

  • Evaluation of the current status of TLB and CRRD and their associated pathogens in various agro-ecological zones of West and Central Africa (WCA)
  • Conservation and characterization of the genetic diversity of C. esculenta and Xanthosoma spp in WCA
  • Improving genetic base of C. esculenta and Xanthosoma spp in WCA through germplasm exchange
  • Initiation of first stages of breeding for disease resistance in C. esculenta and Xanthosoma spp
  • Establishment of a regional network of cocoyam researchers in WCA

Partnering will indeed be necessary for comprehensive and successful interventions. “A regional network could be linked with existing networks in other parts of the world such as the International Network for Edible Aroids (INEA)”, Onyeka suggests.

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By Véronique Durroux-Malpartida