The parasitic angiosperms, Striga hermonthica and S. gesnerioides, obligate root parasites endemic in sub-Saharan Africa, constitute severe constraints to cereal and legume production in West and Central Africa. Over the years, a range of effective component technologies has been identified for Striga control in Africa. The potential of these technologies has been demonstrated under researcher-managed conditions. To promote farmer testing of the technologies, community workshops were conducted in 42 rural communities in Kaduna State, northern Nigeria. These revealed that agriculture was the main source of livelihood for most households. The three most important crops, maize, sorghum and pearl millet are attacked by S. hermonthica, regarded as the major constraint to crop production, often causing 70–100% crop loss. Farmers recognised two types of Striga damage (underground and aboveground), with greater damage being caused by underground Striga. Farmers attributed increasing incidence and severity of Striga damage to lack of capital, poor soil fertility, infestation of previously uninfested land by Striga seeds, and continuous cropping of host crops. The most widely used among the 15 existing Striga control techniques identified by the farmers were hoe weeding and hand pulling, application of inorganic fertilizer and manure, crop rotations, fallowing, and early planting. In assessing possible control measures farmers considered increased crop yield, reduced Striga reproduction and Striga emergence, greater crop vigour, and increased soil fertility as positive attributes. Negative attributes comprised increased labour requirement, higher costs, increased risk of crop damage or yield reduction, and lower quantity and quality of produce. Overall, a legume-cereal rotation was the most highly rated control option for S. hermonthica management evaluated by the farmers. The implications of these results are examined with respect to farmers' adoption and adaptation of Striga control options beyond the experimental plots.

REFERENCE1 Dalton TJ and Guei RG, Productivity gains from rice genetic enhancements in West Africa: countries and ecologies. World Dev 31:359-374 (2003).

Le manioc est une des tubercules les importantes parmi celles cultivées pour l'alimentation en Afrique de l'ouest et du centre. L'article s'intéresse aux déterminants de la demande de manioc et aux perspectives pour cette culture dans le nord du Nigeria en estimant l'élasticité de la demande de manioc et d'autres racines et tubercules. Le modèle « Système de demande pratiquement idéal » (AIDS) a été utilisé pour estimer les paramètres. Les résultats montrent que la demande de manioc est inélastique par rapport aux prix. L'élasticité par rapport aux dépenses est positive bien que faible. Ceci témoigne de l'évolution du manioc, de bien inférieur à celui de première nécessité. Grâce à ses qualités de conservation, le gari, la forme transformée du manioc, est devenue très populaire. Ce produit qui constitue une excellente source d'énergie alimentaire ne devrait donc pas être seulement considéré comme une culture de subsistance ou la nourriture du pauvre.European Journal of Development Research (2009) 21, 435–447. doi:10.1057/ejdr.2009.15; published online 23 April 2009

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The study focuses on evaluating factors that farmers consider relevant in adopting cassava production in five semi-arid zone of West African countries. The study is based on primary data randomly collected as part of collaborative study of cassava in semiarid zones of Africa (COSCASSA) village level survey from five West African countries namely: Nigeria, Ghana, Chad, Niger and Burkina Faso. This study models effects of farm, farmer and technology specific factors on the decision of semi arid farmers to adopt cassava into their farming system. By way of threshold decision models-Probit and Logit models, the estimation of each country and the pooled data adoption models reveal different adoption models for the countries considered. For each country, different variables appeared as major adoption shifters. Comparatively, the adoption models for Nigeria and whole region appear to have the highest significance variables, being seven in number. This is followed by Chad (6), Ghana (4), and Burkina Faso and Niger with three each. For the variables considered, distance to nearby urban market appears a major adoption shifter in all the country, except for Niger. This is closely followed by contact with extension, variety, pest/disease resistance and livestock feeds, which appear significant in four of the countries. Membership of cooperative societies appears as the least adoption predictor, which is only significant in Chad republic. The study therefore recognizes the importance of varietial characteristics and farmers' characteristics in acceptance of cassava as a major root tuber crop in the semi arid region of West Africa.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.