Browsing by Author "Ddamulira, Gabriel"

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    Agronomic suitability for oil palm growing in Uganda
    (Journal of Agricultural Science, 2024-03-15) Ddamulira, Gabriel; Asiimwe, Alex; Masika, Fred; Amugoli, Moses; Ddumba, Gerald; Maphosa, Mcebisi
    The ever-increasing demand for vegetable oils with its products in Uganda, calls for new areas to be put under oil palm cultivation. A study was conducted to investigate the agronomic suitability of oil palm cultivation in six areas located within a 30 km radius off-shore, on the island and more than 30 km radius off-shore on the mainland. The experiment was superimposed on 45 × 45 m plots in oil palm adaptive trial plantations established in 2008 in Bugiri, Mayuge, Buvuma, Mukono, Kibaale and Masaka districts. The experiment was laid out in a randomized complete block design with three replications. Data on number of oil palm bunches, bunch weight and yield was collected while climatic data (rainfall, temperature, relative humidity and radiation) was acquired from meteorological stations near the experimental locations. Rainfall data analyzed and dry season duration suggested that Mayuge, Masaka, Mukono, Buvuma and Kibaale were moderately favorable for oil palm growing, while temperature and radiation data indicated that all study locations were suitable for oil palm growing. Furthermore, based on relative humidity, Buvuma, Mayuge and Bugiri were suitable for oil palm cultivation but Kibaale, Masaka and Mukono were moderately suitable. Oil palm yield varied significantly (P < 0.05) across locations. The yield was much greater in Mukono (17.7 t/ha/yr) followed by Buvuma (13.8 t/ha/yr) and Kibaale (12.9 t/ha/yr) then Mayuge (10.7 t/ha/yr), Bugiri (10.2 t/ha/yr), and Masaka (10.3 t/ha/yr). The significantly high yield of oil palm observed in Mukono was attributed to the high rainfall received in this location. Based on research findings, Mukono, Masaka, Bugiri, Buvuma, Kibaale and areas within the 30 km radius of Lake Victoria are agronomically suitable for oil palm cultivation.
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    High-throughput sequencing analysis reveals Moroccan Watermelon Mosaic Virus and Tobacco Streak Virus isolates infecting pumpkins in Uganda
    (CABI Agriculture and Bioscience, 2025-08-01) Masika, Fred Bwayo; Tugume, Arthur K.; Kesawat, Mahipal S.; Shimelis, Hussein; Ddamulira, Gabriel; Athman, Shahasi Y.; Ipulet, Perpetua; Alicai, Titus
    Pumpkin (Cucurbita pepo L.) is a globally cultivated, economically significant cucurbit species, yet viral diseases pose a major threat to its yield and quality, especially in key production areas such as Uganda. To investigate and document viruses affecting pumpkins in Uganda, we assessed the sub-regional severity of virus-like diseases and identified pumpkin-infecting viruses using RNA sequencing. A total of 75 pumpkin leaf samples displaying typical viral symptoms were collected from 66 fields across Uganda. These samples were then pooled into five bulk groups, each consisting of 15 different plant leaves. Our analysis identified two viruses and detected six viruses, which were, however, not confirmed by another method. The two identified viruses were Moroccan Watermelon Mosaic Virus (MWMV) and Tobacco Streak Virus (TSV). This is the first report of MWMV and TSV infecting pumpkins in Uganda. The virus-like disease symptoms exhibited variations in sub-regional severity and incidence. These findings highlight the current viral diversity in pumpkins in Uganda, providing critical information for developing integrated disease management strategies to enhance crop yield and productivity.
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    Relative abundance, geographical distribution, and utilization of the edible wild black plum (Vitex doniana) in Uganda
    (Springer Nature, 2025-08-04) Caku, Jimmy; Kesawat, Mahipal S.; Ddamulira, Gabriel; Masika, Fred Bwayo
    Wild edible plants play a crucial role in food security, biodiversity conservation, and sustaining rural livelihoods. Vitex doniana, though widely distributed, remains an underutilized species with significant ecological, economic, and medicinal value. Despite its adaptability across diverse ecosystems, its population in Uganda faces increasing threats from human activities. In addition, the lack of comprehensive data on its abundance and distribution hampers conservation efforts, posing a risk to the plant’s genetic diversity. Ecological and ethnobotanical surveys were conducted in Uganda, Koboko district, to assess the abundance, utilization, and distribution of V. doniana. A total of six line transects and 18 quadrats (three alternating quadrats (50 m × 100 m) with 25 m spacing between quadrats per line transect) were used for data collection. A pre-tested questionnaire was used to collect data on the utilisation of V. doniana from 144 respondents. Data were analysed using descriptive statistics and Chi-square tests in SPSS. Results indicated a higher relative abundance of young regenerating trees (74.0%) than mature trees (26.0%). The distribution of V. doniana across different land-use types showed a statistically significant variation (χ² = 7.17, df = 2, p = 0.028). The local community utilizes the tree for fruit harvesting, firewood, charcoal production, and construction purposes. To ensure the sustainable use of V. doniana, community by-laws, awareness, controlled harvesting, and agroforestry practices should be embraced.
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    Seasonal dynamics of Elaeidobius Kamerunicus in allopatric populations: comparative analysis from indigenous mainland and introduced oil palm ecosystems in Uganda’s lake Victoria islands
    (Taylor & Francis, 2026-02-04) Masika, Fred Bwayo; Otuba, Amugoli Moses; Kesawat, Mahipal Singh; Asiimwe, Alex; Baguma, Bidget; Alicai, Titus; Manohar, Swati; Ddamulira, Gabriel
    Oil palm (Elaeis guineensis L.), native to Africa but widely cultivated in Southeast Asia, is increasingly grown in Uganda, and pollination efficiency is critical for fruit set and oil yield. The study assessed the population and sexual diversity of the primary pollinator, Elaeidobius kamerunicus FAUST, in introduced hybrid plantations in Kalangala and natural stands in Bundibugyo. Pollinator weevils were sampled across both wet and dry seasons in 2022 and 2023, and data were analyzed using ANOVA and correlation tests in Minitab 17. Results revealed significant variation between sites, with higher populations in Kalangala (7,503 ± 8.682) compared to Bundibugyo (5,164 ± 5.829). Furthermore, females (6,636 ± 4.646) outnumbered males (6,032 ± 5.028), with a slightly higher concentration of females in the middle section of male inflorescences. Seasonal differences were evident, as the wet season supported slightly higher weevil populations relative to the dry season. Correlation analysis indicated a weak negative relationship between weevil abundance and weather variables, suggesting that cooler conditions suppress population growth. Overall, Uganda provides favorable conditions for pollinator weevil multiplication, particularly under moist climatic regimes, while extensive cold conditions limit population expansion. These findings highlight the importance of pollinator dynamics in sustaining oil palm productivity in diverse agroecological regions.
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    Trading tomatoes and onions in Uganda’s watersheds: actors, dynamics, and opportunities
    (Canadian Center of Science and Education, 2026-01-15) Masika, Fred Bwayo; Ddamulira, Gabriel; Obongo, Isaac; Aropet, Stella Adumo; Asiimwe, Alex; Kiryowa, Moses; Logose, Maureen; Amugoli, Otuba Moses; Naluyimba, Rehema; Ramathan, Idd
    Horticulture accounts for more than half of Uganda’s agricultural output, yet crops such as tomatoes and onions remain only marginally profitable despite the country’s favorable climate. To assess the state of their marketing, a study was conducted across five watershed irrigation schemes of Ngenge, Tochi, Wadelai, Mubuku II, and Doho. Researchers interviewed 56 key informants and 174 market vendors using questionnaires that explored market actors, their roles and interconnections, seasonal trade dynamics, pricing, supply and demand, gross margins, and both opportunities and constraints. Data were analyzed using Microsoft Excel and SPSS. The findings showed that nearly half of the markets (46%) were underdeveloped, with women and youth making up the majority of vendors (78%). Farmers were the main suppliers, but often overlapped with other market roles. Seasonal fluctuations affected tomato and onion availability, with oblong tomato varieties being most popular. Key challenges included poor storage facilities, high market fees, and price volatility. However, strong local demand, access to export channels, and opportunities for off-season production highlight promising avenues for improving the profitability and sustainability of tomato and onion marketing in Uganda.