Cassava is among the high priority commodity crops on NARO's research agenda. The crop was introduced to Uganda through what is Tanzania by Arab traders between 1862 and 1875. Its cultivation greatly increased between 1931 and 1933 and subsequently became a cheap source of food. It ranks second among the major food crops, regarded as the most important cheap source of staple food and cash crop. Its flexibility in the farming and food systems, ability to do well in marginally stressed environments and apparent resistance/tolerance to pests and diseases, particularly locusts encouraged its rapid spread and adoption. It is presently grown throughout the country. A total of 3.5 million metric tonnes of the crop were produced from 450,000 hectares of land grown until 1990 when mosaic epidemic devastated the crop.

The major constraints that affect cassava production include (a) the use of inferior low yielding varieties; (b) lack of good quality planting material; (c) pests such as cassava mealybug (CM), green spider mite (CGM), (d) diseases, including the current pandemic of cassava mosaic viruses (CMV), cassava bacterial blight (CBB) and anthracnose (CAD), (e) labour bottlenecks and poor cultural practices (f) cyanogenic glucosides which hinder cassava utilisation (g) bulkiness and perishability affecting commercialisation of the crop, (h) poor methods of utilisation.

Goal and Objectives of the Cassava Programme
The Uganda Cassava Development Programme (UCDP) is mandated to carry out research and development activities on cassava improvement in the country. It conducts multidisciplinary research at Namulonge Agricultural and Animal Production Research Institute (NAARI) and other experimental substations located in different ecological regions of the country where the crop is important. The overall goal of the programme is to supply adequate food and raw materials, stimulate production for export in order to raise income and improve quality of rural life while conserving the natural resource base.

Specifically, research objectives are to:-
a) Understand farmer's cassava production and utilisation practices, identify constraints/needs and adjust research priorities and objectives appropriately,
b) Collect and preserve local cassava germplasm and use them in breeding more
adapted, farmer/consumers acceptable varieties resistant to major pests and
c) Develop appropriate, integrated and ecologically sustainable methods for the control of major pests and diseases
d) Develop improved agronomic and post harvest practices acceptable to resource poor farmers and continuously provide in-service and higher degree training facilitate attendance at conferences and workshops by programme staff respectively, in order to form a well co-ordinated inter-disciplinary team which ensures sustainable national capacity.

The specific development objectives are to
a) Carry out accelerated on-farm trials, collaboratively identify improved, appropriate varieties and other technologies acceptable to farmers.
b) Assist extension staff, NGOs etc to multiply and distribute suitable sufficient planting material of varieties to many farmers over the shortest possible time.
c) Continuously to understand the socio-economics, adoption and impacts of root crop technologies
d) Train extension staff, opinion leaders and farmers on improved production/utilization practices.

Support by various stakeholders

Financial support for the programme comes from the Uganda Government and, the International Development Research Centre (IDRC), Canada, USAID - PL 480 (food Security, Washington, International Department for Agriculture Development (DFID), U.K.

The Programme recognised the strategic important role of collaborators in agricultural technology development and transfer and accordingly, strengthened collaboration with many national research systems, international organizations, and, overseas institutions. The programme has developed close linkages with IITA and its Regional Centre for Eastern and Southern Africa (ESARC) by deriving technical and material backstopping.

The Programme is a member of the Eastern Africa Root Crops Research Network
(EARRNET), Cassava Biotechnology Network (CBN), International Bemisia Working Group (IBG) and the Intercenter Whitefly Initiative and many other relevant organisations. The team collaborates very effectively with the post-harvest and soils research team at Kawanda Agricultural Research Institute, (KARI), the Food Research Institute (FORSI), Makerere University and Agricultural University, Wageningen.

Similarly, the programme has solicited support and co-operation from non-governmental organizations, notably CARE (U) International, Lutheran World Federation, ACORD, Agricultural Development Programme (ADP), Farming Systems Support Programme (FSSP), Eastern and Southern African Root Crops Research Network (ESSARN) to mention but a few.

The close linkage between the Programme, policy makers, extension staff, NGOs and farmers has made enormous contribution in development and dissemination of
improved and sustainable cassava technologies. This approach will continue to be
employed in introducing, identifying, evaluating, disseminating and validating improved cassava technologies within the medium to high altitudes and semi-arid areas in Uganda where the potential of cassava in bridging the food gap is immense.

(1) Technology development , (2) Technology transfer

Technology development
A range of both hard and soft technologies have been developed through a concerted interdisciplinary and inter-institutional approach. Todate, 9 varieties have been officially released; TMS 60142, TMS 30337, TMS 30572, SS4, SS5, TMS 4(2)1425, CE 85, CE 98, 30557 code-named Nase 1, Nase 2, Nase 3, Nase 4, Nase 5, Nase 6, Nase 7, Nase 8, Nase 9 respectively. Further, several clones are in advanced stages of evaluation and wait release. Besides other recommendations have been made across disciplines ranging from phytosanitary control measures to improved production husbandry practices. For example, rouging and selection of clean planting materials, planting in isolation, restricted movement of diseased materials, use of varietal mixtures, spacing 1 m x 1 m, stakelength (25-40 cm), intercropping, rapid multiplication techniques, ratooning and safe use of bitter cassava varieties.

Technology transfer

(1)Multiplication of mosaic resistant varieties, (2) On-farm trials, (3) Capacity building, (4) Contribution of knowledge to science, (5) Global spill-overs, (6) Conferences, workshops and courses.

Multiplication of mosaic resistant varieties

Inorder to accelerate the technology transfer process, a machinery, National Network of cassava workers (NANEC) was put in place in 1991. Through this network, research on cassava has been able to register greater successes including development of new mosaic cassava varieties. An integrated strategy for multiplication and distribution of virus-free stocks of improved varieties was developed and used by NANEC. Todate, more than 250,000 ha of improved resistant varieties have been established. By and large, NANEC through its participatory research approaches in the development and transfer of cassava technologies has been overwhelming successful. This is explicitly illustrated by high yields of new cassava varieties that bridged the yield-gap caused by the devastating CMD epidemic, the rapid adoption and uptake of new cassava varieties, and the large and positive internal rates of return (IRR) derived from the overall cassava project and from separate projects. The IRR has been estimated to be between 100 and 200%

On-farm trials
A number of on-farm trials have been conducted throughout the country. The trials enabled identification of cassava genotypes suitable fort he diverse local and farmers' conditions and strengthened the partnership amongst researchers, extensionists and farmers since each had a role to play in the trials. To-date, more than 580 on-farm trials have been conducted.

Capacity building
Nearly all the programme staff has been trained at Masters' and Ph.D. level. The training of farmers and other stakeholders increased farmers' knowledge on mosaic and its control. Currently, there is greater awareness on CMD spread and control than before. Not only did creation of awareness stop at farm level, it went even to other members of the public. The programme has documented some of its activities on video and this has been put for public viewing over Uganda Television at least four times a year since 1996.

Contribution of knowledge to science

The classical study of molecular biology of UgV, particularly DNA-A, has shown that the virus arose through hybridization between torelated viruses, EACMV and ACMV. This is the first report to show that when two related geminiviruses co infect a host, a recombination is possible. This is of great significance because it suggests that geminiviruses could become even more important as more than one species adapt to similar hosts.

The studies has also shown that ACMV and EACMV co-infected cassava. Plants infected in this way showed more severe symptoms that those infected singly. This is important because it suggests that two related geminiviruses can co-infect one host and cause synagestic effects on symptom severity. It demonstrates that mild strain protection is less likely in geminiviruses unlike in other viruses where cross-protection is the order.

Global spill-overs
The knowledge, technologies and experiences generated in Uganda, puts the programme at a unique position to assist neighboring countries experiencing similar problems. The mosaic epidemic has already destroyed much cassava in western Kenya, entered Tanzania and is spreading rapidly in DRC and Southern Sudan. The programme has already been approached to assist in Kenya. A substantial amount of planting material was mobilized and planted as nucleus multiplication at Alupe Research Station and Kakamega Regional Research Station (Fig. 15). The first series of harvests of these stems have been moved to initiate multiplication of mother gardens in a few districts in western Kenya. Plans are underway to expand these to cover multiplication in all districts and sub-counties within districts. Requests have been received from Tanzania. Discussions have been held with the scientists there and plans to initiate multiplication has been drawn up. A similar thing could be extended to DRC and Southern Sudan once insecurity in those countries stops.

Conferences, workshops and courses
The program successfully organised and conducted a number of conferences, workshops and courses such as the International workshop on cassava mosaic disease in Africa organised jointly with NRI; International seminar on integrated management of pests, weeds and diseases of cassava in Africa-organised jointly with CTA, NRI, NARO; the third international scientific conference of the cassava biotechnology network-organised jointly with CBN, CIAT; national workshop on post-harvest technologies for root crops-organised jointly with IITA; Advanced statistical data analysis course (twice)-organised jointly with EARRNET.

Intercropping and cultural management, (2)Cassava varietal Improvement, (3) Integrated pest management, (4) Cyanide Studies, (5) Socio-Economic Studies

Intercropping and cultural management
1) The effect of ratooning and age on cyanogenic potential in cassava
2) Source-link relationship in dry matter partitioning among cassava genotypes in different agro-ecologies
3) Farmer participatory review of cassava agronomic recommendations
4) Farmer participatory development of soil fertility management strategies in cassava production
5) Integrated solutions to weed managemnet in cassava production

Cassava varietal Improvement
1) Evaluation of germplasm for cyanogenic association
2) Collection, evaluation, characterisation and maintenance of germplasm
3) Regional variety trial
4) Yield trials with advanced selections
5) Studies on genotype x environment interaction and yield stability
6) Introgression of ACMV resistance genes into local elite cassava

Integrated pest management
1) Studies on alternative host plants of B.tabaci and CMVs
2) Studies on CMV transmission by B.tabaci using resistant and susceptible varieties as a sources of virus
3) Studies on immigration and emigration of B.tabaci in cassava fields in relation to epidemic progress
4) Comparative study on whitefly infestation in CMV-infected and CMV free cassava
5) Studies on the resistance of cassava to cassava mosaic disease
6) Effect of varietal diversity on the spread of CMD
7) Equilibrium in cassava and the CMD pathosystem
8) Serological and molecular variability of CMGs
9) Nature and dynamics of CMD epidemic
10) Variability and virulence of CMGs in Uganda
11) Evaluation of local cassava clones for susceptibility virus content and type, reversion/recovery and yield
12) Potency of resistant cassava varieties as sources of cassava
13) Progress of cassava mosaic in different forms of varietal mixtures
14) Effect of stage of infection, virus type and content on reversion
15) The impact of use of CMD resistant varieties on variability of CMG
16) Significance of reversion and recovery in the epidemiology of CMD and sustainability of cassava varieties
17) The effect of ratooning cassava on 'reflux' of CMGs
18)Influence of selection and roguing CMD resistant varieties on the incidence of CMD
19) Screening cassava genotypes for resistance to cassava green spider mite (CGM) and cassava mealybug
19) The Interaction between strains of cassava mosaic geminiviruses and effects on growth and yield
20) Studies on replacement series between susceptible and resistant varieties and compensation for virus damages in a CMD-pathosystem.

Cyanide Studies
1) The effect of ratooning and age cyanogenic potential in cassava
2) Evaluation of the cyanogenic potential of cassava-based food products across selected locations
3) Screening of cassava varieties for preferred post-harvest quality parameters (including low cyanide content)
4) Effect of soil chemical factors and soil types on cyanogenic potential
5) Impact of age and season of harvesting; handling methods on cyanogenic potential
6) Quantification of glucosides and linamarase enzyme in different cassava genotypes

Socio-Economic Studies
1) Adoption study of technologies developed on cassava
2) Cassava variety On-farm testing
3) The economics of technologies developed on cassava
4) Farmer coping strategies with CMD at different CMD epidemic stages
5) Issues on participatory research on cassava in Uganda
6) Cassava stem production and quality materials in the major cassava growing areas of Uganda
7) Sensitization of the farming community on improved methods of cassava production
8) Understanding farmers' practices for utilising cassava technologies in CMD post-epidemic areas in Uganda
9) The role of participatory Integrated pest management (IPM) and community-based technology transfer centres (COBTTEC) in development, and adoption of cassava technologies
10) Assessment of the efficiency and impact of different approaches adopted in the testing and transfer of cassava technologies in Uganda



image image image image image image image