Browsing by Author "Karamura, E."

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    An analysis of the risk from Xanthomonas campestris pv. musacearum to banana cultivation in Eastern, Central and Southern Africa
    (Bioversity International, Montpellier, France, 2008) Smith, J.J.; Jones, D.R.; Karamura, E.; Blomme, G.; Turyagyenda, F.L.
    Xanthomonas wilt, which is commonly known in East Africa as banana Xanthomonas wilt (BXW), banana bacterial wilt or enset wilt, is a devastating disease caused by the bacterium Xanthomonas campestris pv. musacearum. It was first reported in 1968 in Ethiopia, where it remained confined until it was observed in Uganda in 2001. The subsequent spread of the bacterium throughout the Great Lakes region, where banana forms a large proportion of the diet, is posing a serious threat to food security. The authors, scientists from the Central Science Laboratory in the UK and Bioversity International in Uganda, discuss the distribution and epidemiology of the causal agent and the measures farmers can use to protect their plants from contracting this deadly disease. They also analyse the impact of the measures deployed to date and make recommendations to reduce the risk of the disease spreading to other countries.
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    Comparative pathogenicity studies of the Xanthomonas vasicola species on maize, sugarcane and banana
    (African Journal of Plant Science, 2015) Karamura, G.; Smith, Julian; Studholme, David; Kubiriba, Jerome; Karamura, E.
    Previous biochemical and molecular sequence analyses of Xanthomonas campestris pathovar musacearum, the etiological agent of banana Xanthomonas wilt, suggest that it belongs within the species Xanthomonas vasicola (X. vasicola pv. vasculorum and X. vasicola pathovar holcicola. However, the X. vasicola pathovar names were considered invalid according to pathovar naming standards and placed as one X. vasicola species; this was also not helped by the lack of sufficient comparative pathogenicity studies. Hence the proposal to rename X. campestris pathovar musacearum was no longer further supported. This study therefore carried out large scale comparative pathogenicity trial studies on the X. vasicola strains and X. campestris pathovar musacearum on 112 plants for banana and maize, and 84 plants for sugarcane, to establish or support the proper X. vasicola pathovar designations. The study also included nine common plant pathogenic Xanthomonas pathovars and one non-Xanthomonas strain. The six strains of X. campestris pathovar musacearum used in the study caused disease in sugarcane and banana but not on maize. 2 and 4 strains of X. vasicola pathovar vasculorum and X. vasicola pathovar holcicola, respectively were not only pathogenic on maize and sugarcane but each also caused distinct symptoms on maize. X. vasicola pathovar vasculorum caused deformation of the plant while X. vasicola pathovar holcicola caused stunted growth.
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    Factors influencing households participation in the Savings and Credit Cooperative (SACCO) programmes in Uganda
    (African Journal of Agricultural Research, 2013) Mpiira, S.; Kiiza, B.; Katungi, E.; Staver, C.; Tabuti, J. S.; Kyotalimye, M.; Muwumba, P.; Karamura, E.; Tushemereirwe, W. K.
    Uganda Cooperative Alliance established SACCO’s as a response to Governments call to provide affordable financial services to rural poor. Over the year’s membership and share capital grew. This study investigated factors influencing household’s participation in SACCO programmes. Participants were disaggregated into savers and none savers. Degree of participation was estimated, an ordered probit function was used to establish likelihood of participation. Member’s participation increased with growth in incomes, dependants in secondary schools. Earning salary, rent, salaried spouse were less likely to participate. Increase in distance from the household to SACCO reduced household’s participation due to increased transaction costs.
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    Garden Tool Transmission of Xanthomonas campestris pv. musacearum on Banana (Musa spp.) and Enset in Ethiopia
    (Harnessing International, 2008) Addis, T.; Turyagyenda, L.F.; Alemu, T.; Karamura, E.; Blomme, G.
    Xanthomonas wilt caused by Xanthomonas campestris pv. musacearum has been an important constraint to enset (Ensete ventricosum) and banana (Musa spp.) in Ethiopia. It was postulated that Xanthomonas wilt has a similar epidemiology as other banana bacterial wilts, which are known to be transmitted by insect vectors and garden tools. A study to determine the role of garden tools in the transmission of Xanthomonas wilt was carried out on enset in a greenhouse at the Southern Agricultural Research Institute, Awassa, Ethiopia and on ‘Pisang Awak’ (AABB genome) in the field at Amaro, Southern Ethiopia. A contaminated knife was used to infect plants. The treatments in the greenhouse trials comprised of cutting: green leaves; broken green leaves; dry leaves; the pseudostem; and roots. Similar treatments were carried out on the field-grown ‘Pisang Awak’ plants with two additional treatments: desuckering and debudding. Debudding was done by cutting off the male bud with a contaminated machete, while a forked stick was used for control samples. In addition, bacterial ooze was smeared on fresh and dry flower and bract scars at the male part of inflorescences. All plants treated with a contaminated machete: enset and banana when cut in the pseudostem; and all banana plants when debudded got infected. Similarly, cutting green leaves and cutting broken green leaves resulted in a high disease transmission of respectively 67 and 62% in banana and 58 and 54% in enset. Similar high transmission rates (90%) were obtained for desuckering on banana. On the other hand, cutting roots with a contaminated machete resulted in low transmission levels, with 20% in bananas and 25% in enset suggesting that tool infections mainly occur above ground. This calls for rigorous tool disinfection, while desuckering and deleafing in highly infected fields should be avoided. Debudding should be carried out with a forked stick.
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    Rehabilitation of Banana Farms Destroyed by Xanthomonas Wilt in Uganda
    (J. Appl. Biosci, 2008) Turyagyenda, L.F.; Blomme, G.; Ssekiwoko, F.; Karamura, E.; Mpiira, S.; Eden-Green, S.
    The measures that have been recommended for banana wilt management in Uganda include debudding, disinfection of garden tools and destruction of diseased plants. However, the adoption rate for these options has been low and the disease has reached epidemic levels. Destruction and removal of the infected plants followed by a fallow period or planting of a crop that is not a host of Xcm, and subsequent replanting with healthy banana suckers could restore banana plantations in areas affected by wilt. This study was carried out to determine the most effective method of destroying infected plants and an appropriate fallow period to ensure replanted suckers are not reinfected. Trials were carried out at three field sites with 68-76% of mats infected at the beginning of the experiment. Treatments evaluated were: (1) killing plants by injecting a herbicide (2,4-D) into the pseudo-stems; (2) plants manually cut down and their rhizomes dug out; (3) plants cut down at ground level and re-sprouting suckers continuously mechanically removed. The banana plant debris was piled on ridges between the plots. Replanting with healthy banana suckers started one month after clearing the diseased plants, using tissue culture plantlets of cultivar Pisang Awak and Mpologoma. A portion of the field was replanted each month up to eight months after the onset of the trials. An economic viability analysis of the different options of destroying infected plants was carried out. Banana suckers planted after a one-month fallow period had a 25% survival rate, while all suckers planted after seven and eight months of fallowing survived. Generally, more dead plants were recorded with cv. Mpologoma than cv. Pisang Awak. Incidence of re-infection was highest in the plots where re-sprouting suckers were being continuously removed and lowest in plots where plants had been completely uprooted. A fallow period of at least six months is required to restore health to farms after infection by Xanthomonas wilt. Complete uprooting of infected plants and removing plant debris onto ridges is the best option for managing Xanthomonas wilt. However, the economic viability analysis indicated that farmers preferred to use herbicide to kill the plants rather than uprooting which is more laborious and expensive. The use of herbicide is hence recommended followed by a 6 month fallow or crop rotation period.