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Project Record

Objectives:

To increase the returns from sweet potato by decreasing both the indirect and the direct ways in which sweet potato virus disease (SPVD) and other pests constrain the productivity of sweet potato in East Africa.

Background:

In Africa, sweet potato is grown particularly by poorly-educated, resource- poor farmers, especially women, usually mostly for family consumption but also for cash: the crop is an important means of poverty alleviation. The crop is particularly important in East Africa (Uganda has the largest production in Africa; Tanzania has the second largest area of production but only the seventh largest production due to poor yields). The crop can grow in relatively marginal soils and its ability to yield quickly with the onset of rains, even intermittent ones, is invaluable in times of food insecurity. It is important in disaster relief in areas of East Africa (Tanzania and Kenya) where cassava mosaic disease has destroyed crops of cassava and resistant varieties have not yet been established. Sweet potato virus disease (SPVD) is the most damaging disease of sweet potato in Africa. Affected plants have no worthwhile yield. The disease is particularly common in western and southern Uganda and the western Lake Zone of Tanzania, where the project is focussed. Here, crops with 50% or more affected plants are commonly encountered and average incidences exceed 30%, leading to chronically poor yields and devastating losses to some individuals. The project will provide sweet potato farmers with proven means of increasing the productivity of the crop through integrated control of its main disease (SPVD) and other pests. Because the control measures will involve little or no cost (resistant varieties, phytosanitation) apart perhaps from some additional labour, the methods will favour resource-poor farmers. Poverty in communities is almost always compounded by and maintained by poor nutrition. Sweet potato is a highly nutritious food, especially when both the leaves and the storage roots are consumed. The high vitamin A content of orange-fleshed sweet potato varieties is particularly important in child development and for nursing mothers, in the extreme, preventing blindness and in fighting off common childhood diseases. It may also ameliorate malaria and delay the development of HIV AIDS. The exotic orange-fleshed varieties are susceptible to SPVD so phytosanitation is required to enable their widespread use. The project will take an integrated crop management (ICM), farmer field school (FFS) approach. This experiential method, encouraged by the protocols, manuals and materials developed by the project, will empower farmers through its range of easily accessible information on the causes and control of the disease and pests. The hands-on approach of farmer field schools aims to overcome any literacy barriers. The protocol (ICM FFS) requires extensionists, once trained, to facilitate farmers' experimentation, discovery and understanding, thereby empowering farmers more generally.

Intended Outputs:

SPVD-resistant sweet potato varieties required by farmers and other stakeholders identified through farmer participatory research (FPR).

Phytosanitary (eg: clean planting material, isolation, roguing) methods of controlling SPVD adapted and validated through FPR groups in a) Uganda and b)Tanzania by March 2004.

Protocols, manuals and materials for training farmers in the control of SPVD and other pests developed and validated by March 2005.

A farmer participatory breeding programme for sweet potato initiated in the environs of Lake Victoria in Uganda by March 2003 and having completed 4 cycles of farmer selection by March 2005.

Cadre of trainers in national and regional government and non-government organisations in East Africa skilled in the knowledge of SPVD control.

Progress and Impact:

The project was based at national agricultural research institutes: Namulonge in Uganda and Maruku in Tanzania. The project collaborated closely with farmer groups, 7 in both countries, providing training for facilitators on-station and farmers through project staff, project-trained facilitators and exchange visits amongst the groups. This training process included knowledge of the causes of sweet potato virus disease (SPVD), how to control it by cultural methods and the use and development of resistant varieties. The training also provided a test-bed whereby the project developed and validated training tools and materials.

The project conducted participatory varietal selection (PVS) with farmer groups in both countries testing 9 and 11 cultivars in Uganda and Tanzania respectively. These cultivars included high-yielding SPVD-resistant and high vitamin A orange-fleshed ones. Farmers generally considered all were useful and it was clear from results that what did well in one location and one season did not necessarily do well in other situations. There were trends, however, e.g., Naspot 1 yielded highly in most places and most situations; Naspot varieties were all generally very SPVD-resistant but some were Alternaria susceptible and SPK004 was the most SPVD-resistant of the orange-fleshed cultivars. Farmers seemed keen to receive a 'basket' of varieties so they can select. SPVD resistance was confirmed as an effective means of control. The project also identified more orange-fleshed local varieties as a contribution to the VITA A project.

The project also tested a range of cultural control measures. Farmers generally selected planting material from plants with a healthy appearance. This measure was therefore not tested but the message to do so was reinforced in training. The main cultural control tested was roguing, and this was demonstrably effective to the farmers, decreasing virus spread, increasing yield and improving the health of planting material. Isolation by distance and by a crop barrier were tested. Whilst both were successfully tested, isolation by distance was unsatisfactory because of land shortages and vulnerability of isolated crops, and the sorghum barrier seemed to reduce the yield of the protected sweet potato.

Working with three farmer groups in Uganda and three farmer groups in Tanzania, the project has made farmers aware of how new varieties develop by growing seedlings of superior families and then selecting them, with national programme breeders, through up to 3 clonal generations in communal participatory breeding (PB) trials. Farmers have also taken material to their own gardens to experiment. Farmers retain a small number of clones which appear to be high-yielding, resistant to SPVD and Alternaria and are now being monitored closely by farmers for other necessary quality attributes.

One general constraint highlighted by the close collaboration with farmers was the importance of drought resistance in sweet potato. Drought destroyed several PVS and cultural control trials and was identified as a major reason why farmers did not continue growing the released varieties. It also severely affected the PB trials and one outcome of this is that the surviving selected accessions are likely to be drought resistant as well as disease resistant. Interestingly, unavailability of land in swamps to maintain planting was also a major constraint identified in a survey of SPVD done in Rwanda. There, SPVD was a major problem in one province.

In both Uganda and Tanzania, poster and leaflets explaining in different languages how to control SPVD were developed and used in training programmes for extensionists; a section on SPVD control was also included in a general Farmer Field School Technical Manual. Extensive training was provided to extensionists in Tanzania, especially through a collaboration developed with the Norwegian People's Aid. Planting material of superior varieties was

Project Conclusions:

The project has sustained the livelihoods of poor farmers in East Africa through a variety of measures. The project has worked directly with small-scale farmers, mostly women and including refugees, HIV-AIDS affected families and farmers in refugee-affected areas. Planting material of superior varieties has also been provided to such groups. The project has validated through a participatory approach the provision to farmers of a basket of superior disease-resistant varieties backed up by selecting healthy planting material and roguing young crops. The collaboration with farmers also identified that isolation by distance or crop barriers, whilst effective in reducing spread, was difficult to utilise in practice by small-scale farmers with limited access to land. PB has been developed for sweet potato in Africa for the first time. The protocol enabled farmers to make an effective contribution; although more work needs to be done, it appears that some high-yielding disease resistant and drought tolerant accessions have been identified. Training tools and materials have been developed, improved and used to train farmers and extensionists in Uganda and Tanzania to enable information to be disseminated further. Involvement with NPA has allowed increased impact to be leveraged.

Publications:

BYAMUKAMA, E., MPEMBE, I, KAYONGO, J, ADOLPH, B. and GIBSON, R. (2004) Establishing impact of participatory research in the adoption of new technologies in sweetpotato research in Uganda. Presentation at: International Society for Tropical Root Crops - Africa Branch 9th Triennial Symposium, 31 October-5 November 2004, Mombasa, Kenya.

Associated References:

R7492, B0111, R6115