Browsing by Author "Mulugeta, Tewodros"

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    Application of Integrated Geophysical Techniques for Mapping Ground Water Resource at the Tisabalima Sub Basin, Eastern Amhara Regional State, Ethiopia.
    (Addis Ababa University, 2017-07-03) Mulugeta, Tewodros; Haile, Tigistu (Professor)
    This work which focuses on geophysical study at Tisabalima sub basin has the aim of identifying the groundwater potential zone of the sub basin and locate potential sites for the drilling of test and production boreholes. During this study, Electrical Sounding and Magnetic data were collected, processed and interpreted using additional inputs from geological and borehole data. The electrical survey results have mapped the geeoelctrical/geological units and possible water bearing horizons in the area and these have enabled the selection of drilling sites for each traverse lines that showed the area to have high groundwater potential dominated by a confined aquifer. The area is identified as having alluvial deposits of sand, gravel and clay with a maximum thickness of 205 m. The magnetic results showed that the area is highly affected by regional tectonic settings such as NE-SW and E-W trending faults that could be the main controlling factors for the source of groundwater occurrences and as a discharge zone in the area. The electrical and magnetic results are seen to correspond very well especially in mapping vertical (near vertical) discontinuities like faults and weak zones in the area.
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    The Effects of aLow Toxicity Pesticide on Potato Late Blight, Tomato Leafminer, Potato Tuber Moth and its Major Parasitoid in Potato and Tomato Intercrops
    (Addis Ababa University, 2017-04) Mulugeta, Tewodros; Mulatu, Bayeh (PhD)
    Potato late blight caused by the oomycete Phytophthora infestans (Mont.) de Bary is the most important potato disease worldwide. It causes losses of several billion dollars annually and it is a global threat to potato growers. The pathogen is also equally important in tomato. Even though various resistant cultivars are being released, potato late blight is mainly controlled with intensive application of fungicides. In Ethiopia the pathogen is distributed throughout the potato producing areas. The main rainy season is quite favorable for the growth and development of the disease and loss could reach 100%. Tomato is the second most affected crop by late blight in the country. The potato tuber moth (PTM), Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is one of the most important potato pests worldwide. Tuber damage in storage facilities is the major problem related to PTM infestation. Even though foliar damage is the source of infestation for the damage in stores, it usually causes insignificant yield losses. In Ethiopia field tuber infestation could reach 42%. In addition to potato PTM attacks tomato, eggplant, tobacco and wild solanum species. Tuta absoluta (Meyrick), commonly called tomato leafminer, is a devastating pest of tomatoes. Up to 100% losses have been reported in tomato crops. Even in a condition where control measures have been taken, losses could still exceed 5%. In Ethiopia the pest has been causing severe damage in tomato since 2011. Control of both PTM and tomato leafminer has been mainly with the use of synthetic insecticides. Due to the non-judicious and continuous use of fungicides/pesticides, insects and pathogens are developing resistance, the environment is polluted and non-target organisms are damaged. Furthermore, lack of knowledge in chemical use and low use of personal protective devices during application, mainly in developing countries, is imposing health problem to poor farmers. xix Therefore due to the harmful impacts of pesticides/fungicides use to the environment and human health there is a need to search for a safe alternative to manage pests and pathogens. Phosphite has been identified as a potential alternative to pesticides/fungicides in controlling some herbivorous insects, fungal diseases and oomycetes. The present study investigated the effect of phosphite against PTM, tomato leafminer and potato late blight. Field trails were conducted for three consecutive years to investigate the efficiency of potassium phosphite, a low toxic inorganic salt with direct and indirect toxicity on oomycetes, and its combinations with the Ridomil fungicide against potato and tomato late blight. Two potato, Belete and Jalene, and one tomato, Melka shola, cultivars with different susceptibility to late blight were used. We demonstrated that phosphite combined with reduced dose of fungicides led to an effective suppression of potato foliar blight same as the full recommended dose of the recommended fungicide. In the moderate resistant potato cultivar Belete phosphite alone had adequate foliar protection against foliar late blight. In tomato, phosphite alone was as effective as the recommended dose of fungicide and combination of phosphite and fungicide. Yield was also affected with phosphite and phosphite and fungicide synergism. Treated plants provided far better yield than untreated control plants. Similarly, three years field trials were conducted to investigate the efficacy of phosphite against PTM and tomato leafminer. The study showed that the phosphite treatment did not affect the population density of tomato leaf miner larvae; however, it reduced PTM larvae population density. Furthermore, the direct toxicity of phosphite on mycelial growth, sporangia production and sporangia germination was investigated in a rye-agar and pea broth plate assays, in vitro, in different P. infestans isolates. The isolates responded differently to phosphite treatment with LC50 value between 1.4-4.3mM and their response was dose dependent. xx These findings show that phosphite can be used efficiently against potato and tomato late blight either alone or combined with reduced dose of fungicides. Phosphite has concentration based direct toxic effect on P. infestans, but the toxicity varies between isolates. Therefore phosphite could be a possible a component in the IPM of PTM and late blight. Key words: Fungicide, isolate, pesticide, plant resistance inducers, PTM, synergism, toxicity,
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    Geophysical Investigation for Ground Waterpotential Assessment and Mapping Structures at Alidege Plain, South Afar, Ethiopia
    (Addis Ababa University, 2011-06-06) Mulugeta, Tewodros; Haile, Tigistu (PhD)
    Vertical Electrical Sounding data collected over the Alidege Plain, located in the Zone 2, of the Afar Regional State has been used in this work. The plain is an extensive flat northeast- southwest running plain in the middle Awash valley with an average width of 26-30Kms and length of more than 70kms. The objective of the VES survey was to make an assessment of the groundwater potential of the plain, with a view to developing the plain both for agricultural and pastoral uses. A total of 90 VES, collected at different field campaigns by the Water Works Design and Supervision Enterprises, has been used. The VES are well distributed over the plain and also a good number of the VES are aligned to enable one to construct a number of sections to depict the subsurface geology of the area. All the VES were individually first interpreted, and to aid in the interpretation of the data, the data were further presented in the form of apparent resistivity pseudodepth sections, sliced-stacked pseudodepth depth sections and true resistivity 2D geoelectric sections. A number of available boreholes distributed over the area were also used to calibrate the VES interpretation. From the combination of these interpretations, it is found that the Alidege plain has adequate groundwater potential with the thick layers of moderately to highly fractured basalts and ignimbrite bearing the good portion of the groundwater resource. A number of structures have also been mapped at varying depths that could control the movement of groundwater and also aid in the location of productive boreholes. From the sliced-stacked pseudodepth sections, it has also been possible to show the direction of regional groundwater movement in the subsurface to be from northeast direction towards southwest direction.
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    Risk factors of birth asphyxia among newborns delivered at public hospitals of Addis Ababa, Ethiopia, 2019.
    (Addis Ababa University, 2019-06) Mulugeta, Tewodros; Sebsibe, Girum(MSc, Assistant professor); Abebe, Fikirtemariam(BSc, MSc)
    Background: - World Health Organization defined birth asphyxia as the failure to initiate and sustain breathing at birth. Globally, 23% of neonatal mortality occurs due to birth asphyxia and in Ethiopia, 31.6% of neonatal mortality occurs due to birth asphyxia. The effect of birth asphyxia is not limited only to death but also has a short and long term neurodevelopment sequel, including cognitive and motor disabilities which are almost untreatable. Objective: - The objective of this study was to assess risk factors of birth asphyxia among newborns delivered at public hospitals of Addis Ababa, Ethiopia, 2019. Methods: Institutional based unmatched case-control study was conducted with a total sample size of 213 (71 cases and 142 controls) in Addis Ababa public hospitals from March 1–April 30, 2019. Cases were selected consecutively using consecutive sampling technique and controls were selected by systematic random sampling method. Data was collected using structured questionnaire through face to face interview with index mothers, measurements and chart record review using checklist. The collected data was entered to Epi data version 4.4 and exported to SPSS version 25 for analysis. Finally, it was analyzed by binary logistic regression model. Variables with (p< 0.25) in bivariate analysis were entered to multivariable logistic regression. Statistical significance was declared at P<0.05. Result: - In this study, 70 cases and 140 controls with their mothers were included with the overall response rate of 98.5%. After doing multivariable logistic regression analysis, significantly associated variables with birth asphyxia were: Anti-partum hemorrhage [AOR=7.17,95%CI(1.73-29.72)], low birth weight [AOR=2.87,95%CI(1.01-8.13)], preterm birth [AOR=3.4, 95%CI (1.04-11.16)], caesarean section delivery[AOR=2.75,95%CI (1.01-7.42)], instrumental delivery[AOR=4.88,95%CI(1.35-17.61)], fetal distress [AOR=4.77, 95%CI (1.52-14.92)] and meconium stained amniotic fluid [AOR=9.02,95% CI(2.96-30.24)]. Conclusion: Antepartum hemorrhage, cesarean section delivery, instrumental delivery, meconium stained amniotic fluid, fetal distress, preterm birth and low birth weight were found to be the risk factors of birth asphyxia. For thus, efforts should be made to improve the quality of antenatal care and intranatal care services to prevent those identified risk factors of birth asphyxia.