Browsing by Author "Turyagyenda, L."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Banana Xanthomonas wilt in Ethiopia: Occurrence and insect vector transmission(African Crop Science Journal, 2008) Ahimelash, D.; Alemu, T.; Addis, T.; Turyagyenda, L.; Blomme, G.Bacterial wilt caused by Xanthomonas vasicola pv. musacearum (Xvm) is an important disease of enset and banana in south and south-western Ethiopia where, the diversity of the insect fauna on banana inflorescences was unknown and the role of insects as vectors of the disease had not been studied. The objectives of this study were to assess the occurrence of bacterial wilt and male bud infection, the diversity of insect families in banana plantations and the presence of the bacteria on insects collected from diseased inflorescences in south and southwestern Ethiopia. Surveys were carried out and insects were collected from three different zones in 2005. The diversity and richness of the insect families was assessed across sites and genotypes and comparisons were made using the Shannon Diversity Index and the Jack knife estimator, respectively. Correlations were made between the abundance and incidence of insects with the incidence of male bud infection on ‘Pisang Awak’ plants. A wide range of insect families were recorded and they varied according to banana genotype and altitude. The Drosophilidae and Apinae families were most frequently recorded across sites and genotypes. The ‘Wendo’ variety (AAA Cavendish group) had the highest diversity and richness of insect families within and across sites. In contrast to the Kembata Tembaro and Bench Maji zones, severe and widespread male bud infection of banana was found in Kaffa, where there was a high diversity of insects on the ‘Pisang Awak’ and ‘Abesha muz’ plants. The incidence of male bud infection on ‘Pisang Awak’ plants was highly correlated with the incidence of insects (R2 = 0.964). The incidence of male bud infection however depends on the floral morphology and altitude. Artificial inoculation with Xvm ooze on fresh male bract and flower scars resulted in infections on ‘Pisang Awak’ and ‘Abesha muz’ plants, but the ‘Dwarf Cavendish’ plants with persistent bracts and flowers remained healthy. Few male bud infections were observed at altitudes above 1,700 masl. Xvm was isolated from Apinae, Lonchaeidae, Muscidae, Tephritidae and Vespidae insect families. Lonchaeidae (Silba spp.) were frequently observed on banana bract and flower scars and could thus be an important insect vector of Xvm in Ethiopia.Item Banana Xanthomonas wilt: a review of the disease, management strategies and future research directions(African Journal of Biotechnology, 2007) Biruma, M.; Pillay, M.; Mwangi, M.; Muchunguzi, P.; Nyine, M.; Turyagyenda, L.; Eden-Green, S.Banana production in Eastern Africa is threatened by the presence of a new devastating bacterial disease caused by Xanthomonas vasicola pv. musacearum (formerly Xanthomonas campestris pv. musacearum). The disease has been identified in Uganda, Eastern Democratic Republic of Congo, Rwanda and Tanzania. Disease symptoms include wilting and yellowing of leaves, excretion of a yellowish bacterial ooze, premature ripening of the bunch, rotting of fruit and internal yellow discoloration of the vascular bundles. Plants are infected either by insects through the inflorescence or by soil-borne bacterial inoculum through the lower parts of the plant. Short- and long-distance transmission of the disease mainly occurs via contaminated tools and insects, though other organisms such as birds may also be involved. Although no banana cultivar with resistance to the disease has been identified as yet, it appears that certain cultivars have mechanisms to ‘escape’ the disease. Management and control of the disease involve methods that reduce the inoculum’s density and spread of the pathogen. Removal of the male bud (de-budding) has proven to be very effective in preventing the disease incidence since the male bud appears to be the primary infection site. The economic impact of banana Xanthomonas wilt is not fully understood but its impact on food security in the region is very significant. While germplasm screening for the disease is ongoing, efforts to genetically engineer resistance in some banana cultivars are also making good progress. This paper presents a review of the disease and management strategies that have been successful in curtailing its spread.Item Identification of drought related and drought responsive genes in cassava(Biosciences for eastern and central Africa, 2010) Turyagyenda, L.; Kizito, B.E.; Morag, Ferguson; Jagger, Harvey; Osiru, D.Conventional cassava breeding has yielded a lot of progress for many traits including pest and disease resistance and high yields but little progress has been made with respect to drought tolerance. It is believed that molecular breeding offers a possibility of efficiency and precision in introgression of drought tolerant genes. Several studies show that several genes respond to drought stress and some of them have been used to improve stress tolerance of plants through gene transformation. Unfortunately such studies have not been carried out in cassava. This research is aimed at identifying genes responsive to drought stress in cassava using Real-Time PCR. Identification of drought tolerance genes will help in understanding the mechanisms of drought tolerance in cassava and may be useful in developmental of drought tolerant crops through genetic transformation. The research has only just started by first observing response of 53 cassava genotypes under water stress conditions.Item Participatory selection and development of drought tolerant cassava varieties for farmers in marginal areas(RUFORUM., 2010) Osiru, D.S.O.; Balyejusa-Kizito, E.; Bisikwa, J.; Baguma, Y.; Turyagyenda, L.Most breeding experiments suffer from the disadvantage that the major stakeholders are not involved in the selection and development of the varieties. This scenario leads to poor adoption and diffusion of the resulting technologies. Participatory plant breeding reduces the chances of developing varieties which, for reasons unknown or overlooked by the breeder, are not acceptable to farmers. Farmers’ participation in research and decision making in variety selection enhances adoption. Through participatory variety selection (PVS), farmers also gain skills, information and knowledge about improved varieties. Most previous research in cassava have not involved farmers in the development of the technologies. This research will involve farmers in the participatory selection of farmer preferred cultivars for breeding to improve their Water Use Efficiency (WUE) in drought prone environments of Uganda.