Highlights - Central Africa
Healthy banana planting materials in Burundi
In Burundi, the improved variety FHIA-17 is gradually replacing the most common dessert bananas “Kamaramasenge” and “Gros Michel”, widely cultivated in the rural areas increasingly being affected by Xanthomonas wilt, but its availability is constrained by lack of healthy planting material.
For easier access for farmers and to ensure a regular source of healthy suckers, NGOs in Burundi are adopting the concept of tissue culture mother gardens for subsequent macropropagation and false decapitation. Such gardens are managed by NGOs and agricultural extension agents to bridge the gap between the farmers and the private suppliers of tissue culture plantlets by disseminating healthy banana planting material from properly managed plots and thereby preventing the spread of pests and diseases. This model increased the demand for tissue culture plantlets in major banana producing areas in the country.
Climate change strategies in Efoulan, Cameroon
Timber trees play an important role in aboveground carbon stocks and appropriate cocoa farm management including fruit and timber trees can increase carbon stocks and farm income. Efoulan is one of the poorest municipalities of southern Cameroon, but it is an ecologically and economically valuable forest region under serious threat of deforestation and forest degradation from the actions of local people through the establishment of food and cash crops (cocoa and oil palm) plantations and from logging.
The Reducing Emissions from All Land Uses (REALU) aims to greatly increase the effectiveness of the Reducing Emission from Deforestation and Forest Degradation (REDD+) mechanism by developing methods and tools that include all transitions in land cover affecting carbon storage. More attention is focused on the interactions between forest carbon stocks, other carbon stocks affected by land use, the major drivers of land use and forest change, and the livelihoods of the hundreds of millions of people in the forest margins in the humid tropics. REALU’s activities in Efoulan area were based on the need to account for all sources of emissions to fulfill the targets for mitigation and emission reduction.
Controlling banana bunchy top in Cameroon
Banana bunchy top disease (BBTD) is one of the most serious threats to plantain and banana production. The global disease is caused by banana bunchy top virus (BBTV genus Babuvirus, family Nanoviridae) and has been reported in 14 African countries. Plants infected early in their growth do not produce fruit, resulting in total yield loss.
IITA in collaboration with national and international partners has been conducting research―largely in West and Central Africa where nearly 90% of the world’s plantain are produced―to understand the virus and vector diversity, disease epidemiology, plant-virus-vector interactions, and factors affecting vector abundance for the purpose of developing economically and ecologically-based options for the sustainable management of BBTD.
In an ongoing experiment in an infected area in southern Cameroon, we have so far followed the development of the disease and the population of the aphid vector of the causal agent for more than two years using 16 Musa genotypes. Symptom expression of BBTD varies widely among the genotypes without any specific patterns related to their genomic composition.
Findings show experimental evidence of the susceptibility to BBTD and aphids in local and hybrid plantain and cooking banana used in West and Central Africa and provide a basis for the selection of Musa genotypes in which BBTD disease develops slowly. These genotypes can be combined with other management measures, such as the use of disease-free planting material as well as vector control for sustainable BBTD management in sub-Saharan Africa.
Processing for quality cassava flour in DR Congo
Cassava is the most important food crop in the Democratic Republic of Congo (DRC). Within two days after harvest, the perishable cassava tubers are traditionally processed to more storable products, particularly chips, fermented paste, and chikwangue. Generally, cassava tubers are manually processed,hHowever, most marketed chips in DRC are of low quality due to poor drying conditions leading to fungal colonization. The chips are almost exclusively sold in local and rural markets as the low quality prevents supermarkets from stocking the products.
Through an IITA-led project on Cassava Rehabilitation in Response to the Outbreak of Cassava Mosaic Disease in the DR Congo, high yielding and disease-resistant varieties were introduced and disseminated in targeted areas. In its second phase, the project initiated the diversification of cassava uses, and introduced improved cassava processing technologies, mainly chippers, graters, presses, and concrete fermentation tanks.
With the introduction of cassava chippers for micro-chip production, the quality of cassava chips and flour improved dramatically. The possibility of processing large quantities of roots by using machines encouraged both rural processors and small entrepreneurs to produce high quality chips and flour.
ISFM boosts productivity of cassava-based systems in DRC
Cassava is cultivated in diverse agro-ecosystems in DRC. Mixed cropping systems where cassava and common beans are among the main food crops are cultivated in the highlands; cassava mono-cropping is done in marginal fields; some practice cassava - legume intercropping, and others slash-and -burn agriculture where cassava is grown for one or two years, followed two to four years fallow.
Most farmers have no access to improved varieties, and have limited opportunities to improve soil fertility. The utilization of improved varieties resistant to pests and diseases in combination with appropriate rates of NPK fertilizer was observed to result in a 30 - 160% increase in cassava root yields in East DR Congo and a visible increase in stem yields, important for planting material production. In West DR Congo, cassava yields doubled from 12 to 25 t/ha with moderate rates of NPK fertilizer, and reached over 40 t/ha-1 with higher rates of fertilizer application.
Fertilizer response and the effect of combining inorganic and organic nutrient resources were also evaluated in cassava systems. The most common fertilizer, NPK 17:17:17, was applied in West DR Congo with or without green manure made from Tithonia sp. or Chromolaena sp., and the effects on storage root yield were evaluated in two locations with differing soil fertility status.
In East DR Congo, the use of improved germplasm did not result in yield increases without the simultaneous implementation of other Integrated soil fertility management (ISFM) components such as modifying the crop arrangement.
Soybean affected cassava yields negatively because of its high biomass production and long maturity period; modifications are needed to integrate a soybean intercrop into the system.
Due to the high variability in soil fertility status, the varying landscape features, and the variation in access to inputs for cassava-producing households, local adaptation is required to ensure that the investments made in cassava production result in the highest returns on investment, in line with the resources (e.g., cash, land, labor) that these households have.