Potato was introduced in Nepal in late seventieth century but it was recognised as one of the major food crops only in 1950s. Consequently, potato development programme was started in 1960. In the beginning the main priority was introduction, multiplication and distribution of newer high yielding varieties to increase productivity. National potato Development Programme wa established in 1972 to address various issues of potato research and development. However, these programmes were geared up only after 1978 with technical and financial support of Swiss Development Cooperation and International Potato Centre. As a result, area covered by potato and its production was increased notably since 1980s. However, improvement in productivity is marginal due to various technical constraints and lack of cold storage, road, and organised marketing systems . Current productivity for potato is estimated at 8.65 t/ha. Due to lack of robust seed production programme, bacterial wilt (Pseudomonas solanacearum) was disseminated to many potato growing areas. Viruses were considered as one of the major potential threat to production in terai areas. Therefore, tissue culture and true potato seed (TPS) technologies were started during the 1980s. The works on TPS is still under progress, while the tissue culture technology has been effective to multiply and produce healthy pre-basic seed potatoes of different varieties.

Potato was introduced in Nepal in late seventieth century but it was recognised as one of the major food crops only in 1950s. Consequently, potato development programme was started in 1960. In the beginning the main priority was introduction, multiplication and distribution of newer high yielding varieties to increase productivity. National potato Development Programme wa established in 1972 to address various issues of potato research and development. However, these programmes were geared up only after 1978 with technical and financial support of Swiss Development Cooperation and International Potato Centre. As a result, area covered by potato and its production was increased notably since 1980s. However, improvement in productivity is marginal due to various technical constraints and lack of cold storage, road, and organised marketing systems . Current productivity for potato is estimated at 8.65 t/ha. Due to lack of robust seed production programme, bacterial wilt (Pseudomonas solanacearum) was disseminated to many potato growing areas. Viruses were considered as one of the major potential threat to production in terai areas. Therefore, tissue culture and true potato seed (TPS) technologies were started during the 1980s. The works on TPS is still under progress, while the tissue culture technology has been effective to multiply and produce healthy pre-basic seed potatoes of different varieties.

The acreage of potato in Nepal is about 4% of the total cultivated land and the average productivity is 8.6 tlha which is quite low by international standards. Several factors may affect yield including a number of diseases. Bacterial wilt caused by Pseudomonas solanacearum E.F. Smith is one of the major diseases of potato, which is becoming a serious constraint to potato production particularly in the hills. The disease has been reported to be spread through seed potatoes in many potential potato growing areas of the hills, foothills and valleys of eastern, central and western development regions of the country. Either ignorance or innocence of technicians and/or growers on the nature of the pathogen and its mode of dissemination has resulted in gradual spread of the disease to new areas. Various authors have estimated losses in yield ranging from 5 to 100% due to bacterial wilt or brown rot. Besides potato, the pathogen has been reported to infect important vegetable crops like tomato, eggplant and chili causing significant losses in production. The races of the bacterium occurring in Nepal have been identified as race 3 (Biovar 2) and race 1 (Biovar 3). So far, potato varieties resistant to brown rot are not available attempts have been made to manage the disease through integrated approaches such as crop rotation, planting of clean seed, soil amendment and field sanitation along with the participation of the farmer community.

The acreage of potato in Nepal is about 4% of the total cultivated land and the average productivity is 8.6 tlha which is quite low by international standards. Several factors may affect yield including a number of diseases. Bacterial wilt caused by Pseudomonas solanacearum E.F. Smith is one of the major diseases of potato, which is becoming a serious constraint to potato production particularly in the hills. The disease has been reported to be spread through seed potatoes in many potential potato growing areas of the hills, foothills and valleys of eastern, central and western development regions of the country. Either ignorance or innocence of technicians and/or growers on the nature of the pathogen and its mode of dissemination has resulted in gradual spread of the disease to new areas. Various authors have estimated losses in yield ranging from 5 to 100% due to bacterial wilt or brown rot. Besides potato, the pathogen has been reported to infect important vegetable crops like tomato, eggplant and chili causing significant losses in production. The races of the bacterium occurring in Nepal have been identified as race 3 (Biovar 2) and race 1 (Biovar 3). So far, potato varieties resistant to brown rot are not available attempts have been made to manage the disease through integrated approaches such as crop rotation, planting of clean seed, soil amendment and field sanitation along with the participation of the farmer community.

The importance of biovar 2 of Pseudomonas solanacearum (syn. Burkholderia solanacearum ; syn. Ralstonia solanacearum) in cool temperate climates has been recently emphasised by outbreaks of potato brown rot disease in some European countries. Dissemination of the pathogen in latently infected potato tubers and in contaminated irrigation water and overwintering in aquatic roots of the weed host Solanum dulcamara have been implicated.  Evidence from the literature suggests that in cool climates the organism is unlikely to persist long term in soil in the absence of a susceptible host. Effective control strategies rely on the enforcement of quarantine legislation at both national and European Community levels. This requires knowledge of the biology of the pathogen in cool environments, methods for accurate monitoring of its survival and distribution at and around disease outbreak sites and application of effective measures for pathogen exclusion, containment and eventual eradication. This paper reviews current knowledge on the above.

The importance of biovar 2 of Pseudomonas solanacearum (syn. Burkholderia solanacearum ; syn. Ralstonia solanacearum) in cool temperate climates has been recently emphasised by outbreaks of potato brown rot disease in some European countries. Dissemination of the pathogen in latently infected potato tubers and in contaminated irrigation water and overwintering in aquatic roots of the weed host Solanum dulcamara have been implicated.  Evidence from the literature suggests that in cool climates the organism is unlikely to persist long term in soil in the absence of a susceptible host. Effective control strategies rely on the enforcement of quarantine legislation at both national and European Community levels. This requires knowledge of the biology of the pathogen in cool environments, methods for accurate monitoring of its survival and distribution at and around disease outbreak sites and application of effective measures for pathogen exclusion, containment and eventual eradication. This paper reviews current knowledge on the above.

Screening of potato genotypes against bacterial wilt caused by Pseudomonassolanacearum has been started at the Horticulture Farm, Kirtipur, in 1975 and continued there until1979. Later the work was re-initiated at the Nucleus Seed Potato Production Centre, Nigale, Sindhupalchok in 1987 and has continued till now. At both locations, screening was done in plots naturally infested with the pathogen. The disease reaction was evaluated by observing presence or absence of disease symptoms . Till1995, 112 potato genotypes received from various sources were tested against the pathogen. Of them 87 genotypes were tested only once and 31 genotypes were tested twice or more times.  Of 87 genotypes tested only once in different years, 32 genotypes were found free from the disease. Some Wisconsin lines such as MS and BR clones were found free from the disease in all tests. Potato genotypes free from the disease in two or more tests were BR-63.65, MS-35.24, MS-35 .25, MS-35.22, MS-36.3, MS-63.5 and MS-70.23. In this paper, limitations in the testing methods and conditions leading to inconsistency in the results are discussed.

Screening of potato genotypes against bacterial wilt caused by Pseudomonassolanacearum has been started at the Horticulture Farm, Kirtipur, in 1975 and continued there until1979. Later the work was re-initiated at the Nucleus Seed Potato Production Centre, Nigale, Sindhupalchok in 1987 and has continued till now. At both locations, screening was done in plots naturally infested with the pathogen. The disease reaction was evaluated by observing presence or absence of disease symptoms . Till1995, 112 potato genotypes received from various sources were tested against the pathogen. Of them 87 genotypes were tested only once and 31 genotypes were tested twice or more times.  Of 87 genotypes tested only once in different years, 32 genotypes were found free from the disease. Some Wisconsin lines such as MS and BR clones were found free from the disease in all tests. Potato genotypes free from the disease in two or more tests were BR-63.65, MS-35.24, MS-35 .25, MS-35.22, MS-36.3, MS-63.5 and MS-70.23. In this paper, limitations in the testing methods and conditions leading to inconsistency in the results are discussed.

Bacterial wilt, caused by Pseudomonas solanacearum E.F. Smith, is the second most limiting phytopathological factor to potato production in the world. Resistant germplasm is available for temperate potato growing regions where Race 3 of the pathogen is prevalent. New tools of molecular biology have led to more precise analysis of the race spectrum of P. solanacearum, demonstrating that race 3 is homogenous throughout the world and that it can therefore have only one point of origin from where it probably spread through the seed potato trade. If the use of resistant germplasm is combined with agronomic measures and use of clean seed, successful potato production is, as a rule, possible, and race 3 can even be eliminated, as already demonstrated in some regions. Resistant commercial germplasm currently available has derived its resistance from the diploid cultivated Andean potato species Solanum phureja. New genetic material with resistance derived from wild species is showing promise in field tests. Wild species can be successfully utilized in a relatively brief period of time if major crossing and selection work is carried out at the diploid level. Non resistant European and possibly Indian tuberosum germplasm, well adapted to heat conditions, is often not affected by BW in the field because adaptation plays a major role in the expression of resistance. To grow potatoes under conditions of P. solanacearum infestation is a more or less successful co-existence with the disease. This co-existence is aided by crop rotation, inter-cropping, specific cultural practices, or flooding if potatoes are cultivated after wetland rice.

Bacterial wilt, caused by Pseudomonas solanacearum E.F. Smith, is the second most limiting phytopathological factor to potato production in the world. Resistant germplasm is available for temperate potato growing regions where Race 3 of the pathogen is prevalent. New tools of molecular biology have led to more precise analysis of the race spectrum of P. solanacearum, demonstrating that race 3 is homogenous throughout the world and that it can therefore have only one point of origin from where it probably spread through the seed potato trade. If the use of resistant germplasm is combined with agronomic measures and use of clean seed, successful potato production is, as a rule, possible, and race 3 can even be eliminated, as already demonstrated in some regions. Resistant commercial germplasm currently available has derived its resistance from the diploid cultivated Andean potato species Solanum phureja. New genetic material with resistance derived from wild species is showing promise in field tests. Wild species can be successfully utilized in a relatively brief period of time if major crossing and selection work is carried out at the diploid level. Non resistant European and possibly Indian tuberosum germplasm, well adapted to heat conditions, is often not affected by BW in the field because adaptation plays a major role in the expression of resistance. To grow potatoes under conditions of P. solanacearum infestation is a more or less successful co-existence with the disease. This co-existence is aided by crop rotation, inter-cropping, specific cultural practices, or flooding if potatoes are cultivated after wetland rice.

Agricultural weed and rotational crop spp., common to the high hill potato produc ion areas  in  Nepal, were  tested  to  determine  their  potential  as  hosts of  race 3 of Pseudomonas solanacearum, the causal agent of bacterial wilt or brown rot of potato. Tests were conducted under screenhouse and glasshouse conditions in Nepal and the UK respectively and a survey was conducted in Nepal to explore the incidence of natural infection. Artificial inoculation was performed by drenching cut roots of potted seedlings with a suspension of a potato isolate of biovar 2 of the bacterium.  Brassica juncea (mustard cv. Fine White), Portulaca oleraceae, Drymaria cordata and Cerastium glomeratum were susceptible to infection when artificially inoculated with the bacterium. Surface sterilised roots of these   plants contained an estimated 1ct to 108  colony­ forming units (cfu) per g of fresh root. One of 12 mustard seedling developed typical wilt symptoms, whereas other infected spp. remained symptomless. In C. glomeratum, infection tend .to localise in roots two months after inoculation whereas, it spread systemically into the stems of the other infected spp. Systemic root infection was also detected in Solanum xanthophyllum after one month but not after two months. Other spp., such as Polygonum capitata and Galinsoga paNiflora, although not infected systemically maintained high rhizosphere populations of the pathogen. Whereas P. so/anacearum declined to an undetectable level in unplanted soil within one month of inoculation, the bacterium could be recovered from the rhizosphere of all test plants for up to two months. Under natural conditions in bacterial wilt affected potato fields, infected plants of G. paNiflora, G. ciliata and P. capitata were identified although the frequency of infection was often low.

Agricultural weed and rotational crop spp., common to the high hill potato produc ion areas  in  Nepal, were  tested  to  determine  their  potential  as  hosts of  race 3 of Pseudomonas solanacearum, the causal agent of bacterial wilt or brown rot of potato. Tests were conducted under screenhouse and glasshouse conditions in Nepal and the UK respectively and a survey was conducted in Nepal to explore the incidence of natural infection. Artificial inoculation was performed by drenching cut roots of potted seedlings with a suspension of a potato isolate of biovar 2 of the bacterium.  Brassica juncea (mustard cv. Fine White), Portulaca oleraceae, Drymaria cordata and Cerastium glomeratum were susceptible to infection when artificially inoculated with the bacterium. Surface sterilised roots of these   plants contained an estimated 1ct to 108  colony­ forming units (cfu) per g of fresh root. One of 12 mustard seedling developed typical wilt symptoms, whereas other infected spp. remained symptomless. In C. glomeratum, infection tend .to localise in roots two months after inoculation whereas, it spread systemically into the stems of the other infected spp. Systemic root infection was also detected in Solanum xanthophyllum after one month but not after two months. Other spp., such as Polygonum capitata and Galinsoga paNiflora, although not infected systemically maintained high rhizosphere populations of the pathogen. Whereas P. so/anacearum declined to an undetectable level in unplanted soil within one month of inoculation, the bacterium could be recovered from the rhizosphere of all test plants for up to two months. Under natural conditions in bacterial wilt affected potato fields, infected plants of G. paNiflora, G. ciliata and P. capitata were identified although the frequency of infection was often low.

A crop rotation experiment was conducted at Pseudomonas solanacearum race 3 infested sites at Sabet (1750 m above sea level) and Ghandruk (2000 m asl) villages in western Nepal. The tested crop rotations were modified from a traditional 18-month period with rotation crops of land potato; barley; finger millet. Mustard, barley, finger millet and cold-toleraot upland rice were used as rotation crops, whereas soil amendment with urea (576 kg ha-1 , lime (2 t ha·\ and roguing of wilted plants were tested as integrated management treatments to control bacterial wilt (BW) of potato.  Bacterial wilt  incidence in the initial potato crop was 18% and 25% at Sabet and Ghandruk respectively and after a short rotation (6-month) involving mustard as a break crop wilt incidence was higher (57% and 97%) than the traditional cropping pattern after 18 months (2% and 12%) for the two sites. The traditional rotation of 18 months with potato-barley-finger millet alone or in combination with soil amendments of urea or lime, and roguing or an 18 months bare-fallow did not eliminate the soil borne bacterium at Sabet, however at Ghandruk urea and roguing had a significant effect on reducing bacterial wilt incidence. No disease at all was observed following a rotation of 30 month with potato-barley-finger millet-upland rice and the results were consistent at both locations.  Testing for latent infection by P. solanacearum on progeny tubers from non-wilted plots of any treatment was conducted to determine whether soil borne populations of P. solanacearum could be eliminated. Tubers harvested from non-wilted plots of all 18- month rotation treatments produced either brown rot during storage or bacterial wilt upon subsequent planting showing that the plants were latently infected. Tubers from the 30-month rotation treatment neither developed brown rot symptoms in storage nor BW on subsequent planting. Results show that 2112 years crop rotation can eliminate the bacterium from an infested soil under natural conditions in the hills of Nepal.

A crop rotation experiment was conducted at Pseudomonas solanacearum race 3 infested sites at Sabet (1750 m above sea level) and Ghandruk (2000 m asl) villages in western Nepal. The tested crop rotations were modified from a traditional 18-month period with rotation crops of land potato; barley; finger millet. Mustard, barley, finger millet and cold-toleraot upland rice were used as rotation crops, whereas soil amendment with urea (576 kg ha-1 , lime (2 t ha·\ and roguing of wilted plants were tested as integrated management treatments to control bacterial wilt (BW) of potato.  Bacterial wilt  incidence in the initial potato crop was 18% and 25% at Sabet and Ghandruk respectively and after a short rotation (6-month) involving mustard as a break crop wilt incidence was higher (57% and 97%) than the traditional cropping pattern after 18 months (2% and 12%) for the two sites. The traditional rotation of 18 months with potato-barley-finger millet alone or in combination with soil amendments of urea or lime, and roguing or an 18 months bare-fallow did not eliminate the soil borne bacterium at Sabet, however at Ghandruk urea and roguing had a significant effect on reducing bacterial wilt incidence. No disease at all was observed following a rotation of 30 month with potato-barley-finger millet-upland rice and the results were consistent at both locations.  Testing for latent infection by P. solanacearum on progeny tubers from non-wilted plots of any treatment was conducted to determine whether soil borne populations of P. solanacearum could be eliminated. Tubers harvested from non-wilted plots of all 18- month rotation treatments produced either brown rot during storage or bacterial wilt upon subsequent planting showing that the plants were latently infected. Tubers from the 30-month rotation treatment neither developed brown rot symptoms in storage nor BW on subsequent planting. Results show that 2112 years crop rotation can eliminate the bacterium from an infested soil under natural conditions in the hills of Nepal.

Bacterial wilt (Pseudomonas solanacearum) is one of the most destructive diseases of potato in the high hills. This disease is difficult to manage due to a lack of resistant varieties and the conducive environment in the high hills for long term survival of the pathogen in soil. Lack of awareness of the disease and its management amongst the farmers has further complicated the problem. An effort has been made by Lumle Agricultural Research Centre to manage the disease in traditional upland potato growing areas of the Western hills with community participatory approach. Key components comprise elimination of infected planting material from the villages, seed multiplication in isolated disease free areas, adoption of three-year rotation with non­ host crops, eradication of volunteer potato plants and farmers' education on crop hygiene and disease management. These were implemented through farmer committees. Experiences show that the approach adopted was technically feasible to manage the disease if the regulations envisaged were followed by all community members. As the reintroduction of the disease due to inter-village exchange of potatoes is the biggest threat to the programme, a strong and effective bacterial wilt awareness campaign in a wider area is urgently needed. Alternative income generating activities such as off-season vegetable production and upland rice cultivation encouraged community cooperation on the programme. Some problems encountered in implementing the programme, potential solutions and areas for further investigation are discussed in the paper.

Bacterial wilt (Pseudomonas solanacearum) is one of the most destructive diseases of potato in the high hills. This disease is difficult to manage due to a lack of resistant varieties and the conducive environment in the high hills for long term survival of the pathogen in soil. Lack of awareness of the disease and its management amongst the farmers has further complicated the problem. An effort has been made by Lumle Agricultural Research Centre to manage the disease in traditional upland potato growing areas of the Western hills with community participatory approach. Key components comprise elimination of infected planting material from the villages, seed multiplication in isolated disease free areas, adoption of three-year rotation with non­ host crops, eradication of volunteer potato plants and farmers' education on crop hygiene and disease management. These were implemented through farmer committees. Experiences show that the approach adopted was technically feasible to manage the disease if the regulations envisaged were followed by all community members. As the reintroduction of the disease due to inter-village exchange of potatoes is the biggest threat to the programme, a strong and effective bacterial wilt awareness campaign in a wider area is urgently needed. Alternative income generating activities such as off-season vegetable production and upland rice cultivation encouraged community cooperation on the programme. Some problems encountered in implementing the programme, potential solutions and areas for further investigation are discussed in the paper.

Bacterial wilt (Pseudomonas solanacearum) is one of the most problematic diseases of potato in the hills of Nepal. It is spreading through traditional seed flow systems favoured by the present socio-cultural and policy environments. This is compromising food security and the livelihoods of hill people. In 1993, an effort was initiated by Lumle Agricultural Research Centre in partnership with User's Perspective with Agricultural Research and Development (UPWARD), Philippines, to manage the disease in the traditional upland potato growing areas of the Western Hills with community participation. After seven years, the approach is yet to achieve its full success largely due to exogenous factors. This paper describes the policy, socio-cultural, and technical constraints. The paper stresses the importance of bringing all stakeholders together to develop common understanding and a vision of future commitments. The success of the programme depends on restricting the free movement of infected seed potatoes through sanctions and political will; ensuring researchers' accountability; increasing public awareness; empowerment of local committees; and the availability of appropriate technology to supply pathogen free/healthy seed. The approach requires considerable resources, effort and time to maintain momentum. Before scaling up, the approach needs to be modified to reduce the limitations encountered over the past years, and to make it less resource-intensive and more locally-manageable.

Bacterial wilt (Pseudomonas solanacearum) is one of the most problematic diseases of potato in the hills of Nepal. It is spreading through traditional seed flow systems favoured by the present socio-cultural and policy environments. This is compromising food security and the livelihoods of hill people. In 1993, an effort was initiated by Lumle Agricultural Research Centre in partnership with User's Perspective with Agricultural Research and Development (UPWARD), Philippines, to manage the disease in the traditional upland potato growing areas of the Western Hills with community participation. After seven years, the approach is yet to achieve its full success largely due to exogenous factors. This paper describes the policy, socio-cultural, and technical constraints. The paper stresses the importance of bringing all stakeholders together to develop common understanding and a vision of future commitments. The success of the programme depends on restricting the free movement of infected seed potatoes through sanctions and political will; ensuring researchers' accountability; increasing public awareness; empowerment of local committees; and the availability of appropriate technology to supply pathogen free/healthy seed. The approach requires considerable resources, effort and time to maintain momentum. Before scaling up, the approach needs to be modified to reduce the limitations encountered over the past years, and to make it less resource-intensive and more locally-manageable.

Pseudomonas solanacearum has continued to disseminate in newer seed production areas due to lack of strict quarantine systems, seed certification schemes, and lack of farmers awareness about the modes of the disease transmission. Consequently bacterial wilt has remained as one of the major production constraints in the hills causing severe losses both under field and storage conditions.Integrated management practices like use of resistant cultivars, crop rotation, crop sanitation, use of disease-free planting materials and other cultural practices are recommended to control the disease. However,  these technologies are not fully exploited in the infested areas due to lack of effective policy and capabilities. Stakeholders like National Agriculture Research Council and the Department of Agriculture has to play the crucial role in implementing the control measures effectively on a wider scale. Most of the users (client or farmers) of the research result do not know of the modes of the disease dissemination and means of long term survival of the pathogen in soil. The possible role of farmers to manage the disease is also discussed in this paper.

Pseudomonas solanacearum has continued to disseminate in newer seed production areas due to lack of strict quarantine systems, seed certification schemes, and lack of farmers awareness about the modes of the disease transmission. Consequently bacterial wilt has remained as one of the major production constraints in the hills causing severe losses both under field and storage conditions.Integrated management practices like use of resistant cultivars, crop rotation, crop sanitation, use of disease-free planting materials and other cultural practices are recommended to control the disease. However,  these technologies are not fully exploited in the infested areas due to lack of effective policy and capabilities. Stakeholders like National Agriculture Research Council and the Department of Agriculture has to play the crucial role in implementing the control measures effectively on a wider scale. Most of the users (client or farmers) of the research result do not know of the modes of the disease dissemination and means of long term survival of the pathogen in soil. The possible role of farmers to manage the disease is also discussed in this paper.

The paper explores the social dimension of pest management and argues that understanding users' perspectives and facilitating user participation can contribute to more effective pest management R&D.Pest problems involve not only technical but also social issues since the field impact of pest management innovations is highly dependent on local communities' social structure, collective representation and meaningful social action. Users' perspectives and participation are particularly critical when the characteristics of insect pests or diseases are such that collective decisions and actions are essential for successful management.The paper focuses on rootcrop agriculture to illustrate the application of user participatory approaches to pest management R&D. Empirical cases drawn from UPWARD projects in various Asian countries describe how researchers work with users in undertaking problem diagnosis, action research and local R&D management. The paper ends by summarizing the key lessons learned_ and how these would compare with the experiences of the community-based bacterial wilt management project in Nepal.

The paper explores the social dimension of pest management and argues that understanding users' perspectives and facilitating user participation can contribute to more effective pest management R&D.Pest problems involve not only technical but also social issues since the field impact of pest management innovations is highly dependent on local communities' social structure, collective representation and meaningful social action. Users' perspectives and participation are particularly critical when the characteristics of insect pests or diseases are such that collective decisions and actions are essential for successful management.The paper focuses on rootcrop agriculture to illustrate the application of user participatory approaches to pest management R&D. Empirical cases drawn from UPWARD projects in various Asian countries describe how researchers work with users in undertaking problem diagnosis, action research and local R&D management. The paper ends by summarizing the key lessons learned_ and how these would compare with the experiences of the community-based bacterial wilt management project in Nepal.

The high hills are the traditional source of seed potatoes in Nepal, informally supplying over 90% to farmers in the mid and low hills. Introduction of bacterial wilt (BW) and wart diseases in many traditional seed producing areas has caused spread of the diseases to low altitude areas through the informal seed flow system.  Production of high quality seed potatoes is a challenging task not only due to disease problems but also due to their bulky nature and special storage requirements. This paper discusses the improvement required in seed production and management systems in the high hills giving due consideration to seed plot techniques.  It explores the possibilities of producing seed potatoes in the mid hills using the paddy rice-potato systems as a means to obtain BW-free seed potato in the hills. Additional care is required for viral disease management and seed storage under these mid-hill conditions. Double cropping of potatoes is presented as an additional option for seed management in the mid-hills. The formal seed potato programme in Nepal is unable to meet national demand and informal sources supply the majority of seed potatoes. A case is made for integrating these two systems to ensure sustainable production of P. solanacearum­ free seed potatoes throughout  the hills of Nepal.

The high hills are the traditional source of seed potatoes in Nepal, informally supplying over 90% to farmers in the mid and low hills. Introduction of bacterial wilt (BW) and wart diseases in many traditional seed producing areas has caused spread of the diseases to low altitude areas through the informal seed flow system.  Production of high quality seed potatoes is a challenging task not only due to disease problems but also due to their bulky nature and special storage requirements. This paper discusses the improvement required in seed production and management systems in the high hills giving due consideration to seed plot techniques.  It explores the possibilities of producing seed potatoes in the mid hills using the paddy rice-potato systems as a means to obtain BW-free seed potato in the hills. Additional care is required for viral disease management and seed storage under these mid-hill conditions. Double cropping of potatoes is presented as an additional option for seed management in the mid-hills. The formal seed potato programme in Nepal is unable to meet national demand and informal sources supply the majority of seed potatoes. A case is made for integrating these two systems to ensure sustainable production of P. solanacearum­ free seed potatoes throughout  the hills of Nepal.