African Cassava Whitefly,Bemisia tabaci,Resistance in African and South American Cassava Genotypes

The whitefly,Bemisia tabaci,is a major pest of cassava,particularly in Africa where it is responsible both for the transmission of plant viruses and,increasingly,for direct damage due to feeding by high populations.To date,there have been no practical solutions to combat this emerging problem,due to the inability of the subsistence farmers that grow cassava to afford expensive inputs such as insecticides.A programme of research was carried out linking institutes in Africa,the UK and South America,to identify possible resistance sources in cassava to the whitefly,Bemisia tabaci.The South American genotype MEcu 72 and several Ugandan cassava landraces including Ofumba Chai,Nabwire 1 and Mercury showed good levels of resistance to B.tabaci.Field and screen-house experiments showed that all of the improved,high-yielding cassava mosaic disease（CMD）resistant cassava genotypes assessed were highly susceptible to B.tabaci and supported high populations of all life stages.These data support the hypothesis that the continuing high populations of cassava B.tabaci in Uganda are due,in part,to the widespread adoption of CMD-resistant cassava varieties during the CMD pandemic.They also show that the whitefly,Aleurotrachelus socialis,resistance present in the South American cassava genotypes could have broader applicability in the Old World.

Trade-offs and synergies of climate change adaptation strategies among smallholder farmers in sub-Saharan Africa:A systematic review

Climate change adaptation strategies provide a cushion for smallholder farmers,especially in subSaharan Africa against the risks posed by climate hazards such as droughts and floods.However,the decision-making process in climate adaptation is complex.To better understand the dynamics of the process,we strive to answer this question:what are the potential trade-offs and synergies related to decision-making and implementation of climate adaptation strategies among smallholder farmers in sub-Saharan Africa region?A systematic literature review methodology was used through the Preferred Reporting Items for Systematic Review and Meta-Analysis(PRISMA)statement with the four-stage inclusion/exclusion criteria to identify the literature from selected databases(Scopus and Google Scholar).The climate adaptation strategies are organized into five broad categories(crop management,risk management,soil/land management,water management,and livestock management strategies).Evidence suggests that potential trade-offs may arise concerning added costs,additional labor requirements,and competition among objectives or available resources.The synergies,on the other hand,arise from implementing two or more adaptation strategies concurrently in respect of increased productivity,resilience,yield stability,sustainability,and environmental protection.Trade-offs and synergies may also differ among the various adaptation strategies with minimum/zero tillage,comparatively,presenting more tradeoffs.The development and promotion of low-cost adaptation strategies and complementary climate adaptation options that minimize the trade-offs and maximize the synergies are suggested.Skills and knowledge on proper implementation of climate change adaptation strategies are encouraged,especially at the local farm level.

Diversity and interaction of common bacterial blight disease-causing bacteria(Xanthomonas spp.) with Phaseolus vulgaris L.

Common bacterial blight(CBB) is associated with common bean(Phaseolus vulgaris L.), an important grain legume for human consumption worldwide. The disease, caused by Xanthomonas spp. is spread mainly through seed. This paper focuses on the diversity of X.axonopodis pv. phaseoli and X. fuscans subsp. fuscans and interactions between related bacteria and the bean host. Review has suggested that the diversity and taxonomic studies of these pathogens are not exhaustive, especially in areas where detailed molecular analysis has not been conducted and previous characterizations were based on phenotypic features and PCR-based techniques. Also, no study has confirmed differential pathogenicity on bean genotypes based on compatible versus incompatible reactions. However, isolates react differently to wild and domesticated bean sources of resistance in common bean genetic backgrounds. A systematic approach will be required to investigate global changes in gene expression among different sources of resistance in a common bean background.The bacterial isolates that cause CBB should be functionally characterized using genotypes containing major quantitative trait loci(QTL) for CBB resistance. These studies will increase understanding of resistance and how it is manipulated by pathogens.

Adoption of technologies that enhance soil carbon sequestration in East Africa. What influence farmers' decision?

The last two decades have seen a rise of interest in the adoption and diffusion of agricultural technologies aimed at improving the sustainability of agricultural lands among smallholder farmers in developing countries.This papers set out to understand factors that influence the adoption of technologies that enhance soil carbon sequestration among smallholder farmers,using secondary data recorded in the World Overview of Conservation Approaches and Technologies(WOCAT)database from 45 to 50 smallholders'farmers in selected places in Kenya and Ethiopia respectively.A Probit model was used to analyse whether socio-economic,institutional,off-farm income,technical know-how,farmers'percep-tions,and land use characteristics influences the adoption of technologies that enhance soil carbon sequestration.The results show that smallholder farmers that positively perceived net benefits of the soil carbon enhancing technologies were more likely to adopt such technologies that enhance soil carbon sequestration in both countries.Access to off-farm income and land ownership with title deeds were also found to be positively associated with adoption.Off-farm income positively influences adoption among farmer with a moderate income(100-500US$per year)but not the rich(>500US$)farmers.Moderate to high level of skills and technical know-how required for implementing and maintaining a technology on the farm had a negative influence on adoption.This shows that interventions,aimed at addressing specific factors such as inadequate skills and knowledge,change in perception among farmers,and off-farm income are likely to have the greatest impact in decisions relating to the adoption of the soil carbon enhancing practices among farmers in East Africa.

Awareness and adoption of land,soil and water conservation practices in the Chinyanja Triangle,Southern Africa

The promotion of land,soil and water conservation measures has been a widespread development in sub-Saharan Africa in a bid to tackle degradation and improve productivity.As a result,several gov-ernments have launched various campaigns on soil,land and water conservation measures.The aim of this study is to determine some of the factors that influence farmers'awareness(knowledge)and adoption of land,soil and water conservation practices.Data for this study was collected from 312 households using a questionnaire survey in the Chinyanja Triangle of Southern Africa.The study sites.were sampled from Tete province of Mozambique,central and southern regions of Malawi and eastern Province of Zambia.We used t-tests to classify adopters and non-adopters of soil,land and water con-servation measures and binomial logit models to identify the factors that infuence farmers'knowledge of conservation measures and adoption of land productivity practices.The results show that the household head's age,education,agricultural advice reception and farmer group membership are critical in raising awareness.While the household head's age,education,agricultural advice reception,farmer group membership,pieces of land owned or used in production and land-to-man ratio influenced adoption decisions.The study,therefore,concludes that in order to improve land productivity in the Chinyanja Triangle,there is a need to consider farmers'heterogeneity in terms of household head's age,level of education,extension services outreach,and socio-economic char acteristics.This suggests that governments'policies in the region should be aimed at improving farmers'level of education,extension delivery that will target the elderly and the youth,land ownership,credit access,and social capital such as group formation.