Browsing by Author "Tushemereirwe, W. K."

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Banana pests and diseases spread to higher altitudes due to increasing temperature over the last 20 years
(Afr. J. Environ. Sci. Technol., 2017-10-16) Erima, R.; Kubiriba, J.; Komutunga, E.; Nowakunda, K.; Namanya, P.; Seruga, R.; Nabulya, G.; Ahumuza, E.; Tushemereirwe, W. K.
In this study, we established changes in minimum and maximum temperature over the past 20 years, and how these changes are likely to affect the status of key banana pests and black Sigatoka disease in main banana cropping systems. A survey was conducted at elevations of 1200, 1400, 1600 and 1800 m above sea level in 13 sites previously used in 1 9 9 2 / 1993. Mean monthly minimum and maximum temperatures at different elevations were computed between 1991 and 2013 and used to determine the temperature change. Data was collected on weevil damage, nematode populations and black Sigatoka severity. Changes in weevil damage, nematode population densities and black Sigatoka severity were determined. Pearson’s correlation analysis was used to establish relationship between minimum and maximum temperature change, changes in weevil damage, black Sigatoka severity and nematode population densities at different elevations. Results show that minimum temperatures in sites above 1400 masl increased by 1°C over the 20 years. Key banana pests and black Sigatoka disease were observed at elevations where they had not occurred before. Change in black Sigatoka disease, Rhadopholus similis, Helicotylenchus multicinctus and Meloidogyne spp. positively correlated with change in both temperature but change in banana weevil’s damages positively correlated with maximum temperature.
Field spread of banana streak virus (BSV)
(Afr. J. Agric. Res., 2012-07-11) Kubiriba, J.; Tushemereirwe, W. K.; Kenyon, L.; Chancellor, T. C. B.
Musa (banana and plantain) provides a major source of carbohydrates for about 400 million people of whom 20 million are from East Africa. Yet, banana is threatened by number constraints, banana streak virus inclusive. Banana streak virus (BSV) was monitored in Rakai and Ntungamo, Uganda for up to 72 months after planting (MAP) and 29MAP respectively. BSV incidence increase over time was fitted into exponential model and spatial spread analysed by 2DCLASS and 2DCORR. BSV infection was initiated in Rakai 29 months after planting (MAP), but only 6 MAP in Ntungamo. BSV incidence then increased at a rate of 0.10 plants respectively / infected plant / month at a rate 0.23 plants / infected plant / month in Rakai and Ntungamo respectively. In both sites, spatial analysis showed that there were significant aggregated BSV spatial patterns. New infections were more likely to occur within a 10 rows/coloumns from an old infection. Significant edge effects were also detected in Ntungamo, indicating that there was significant spread from the immediate surroundings (infected established field suggesting need for separation of new fields from old infected fields to delay onset of BSV. Roguing should be frequent enough to offset rate of BSV incidence increase. The study shows that BSV is a slow spreading disease; however, there is sufficient time in this perennial cropping system for it to increase to epidemic levels. It is however, possible to check the advance of the BSV epidemic through phytosanitary measures.