Dissertations

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Morphological identification and in vitro efficacy of fungicides in control of phytophthora causing pineapple heart rot disease in Uganda
(Kyambogo University (un published work), 2016-12) Ocwa, Akasairi,
Pineapple (Ananas comosus L. Merr) production in Uganda is being constrained by a diversity of factors including pineapple heart rot disease (PHRD). Information on PHRD causal pathogen is limited. Also, management options are clear. The objectives of this study were, therefore, to identify the casual pathogens causing PHRD and assess the in vitro reaction of the causal pathogens to fungicides. Pathogen isolation was done using amended corn meal agar. Macro and micro-morphological characteristics of the isolates were assessed. Pathogenicity of the isolates was tested using healthy pineapple plants based on Koch's postulate. In vitro reaction was determined using I 0% V8 media amended with 0.1 g/L Metalaxyl, 0.1 g/L Victory 72 powder, 0.01 g/Land 0.001 g/L Metalaxyl, 0.01 g/L and 0.001 g/L Fosetyl Al and unamended V8 media as a control. There was a significant difference (P<0.05) in the growth rates, hyphae diameter and asexual structure dimensions of the isolates. Isolates were characterized by a dense rosette and stoloniferous mycelial growth pattern in PDA media. Sporangia were non-caduceus. terminal, papillate and mostly ovoid, obpyriform and limoniform sporangia (32-56μm) with a mean length/breadth ratio of 1.32: I μm . Chlamydospores were spherical and thick-walled (25- 42μm diameter). Sporangiophore branching was sympodial. All the isolates were sensitive to Metalaxyl and Victory 72 powder treatment. Based on the morphological characteristics of isolates, it was concluded that Phytophthora nicotianae is the species associated with PHRD in central Uganda. Additionally, Metalaxyl was the most effective chemical against the pathogen in vitro. Molecular characterization of the pathogen is recommended to confirm the identity of the species. It is also recommended that the efficacy of fungicides which have shown effectiveness be assessed further under field conditions.
Yield loss and resistance to pineapple heart rot disease on pineapple cultivars in central Uganda
(Kyambogo University (un published work), 2017-12) Oculi, jasper
Pineapple (Ananas comosus (L.) Merr) is of tremendous importance as a fruit crop in Uganda. However, production in Uganda is currently threatened by outbreaks of pineapple heart rot disease (PHRD). PHRD is the most widespread and devastating disease of pineapple in Uganda and can cause tremendous yield loss. Although, some preliminary information exists on PHRD in Uganda, the yield loss attributed to the disease has not quantified neither is there any information on sources of resistance. The objective of this study was, therefore, to determine yield loss and resistance to pineapple heart rot disease in central Uganda. In order to address these objectives, five cultivars of pineapple were planted in the screen house and in the field in a completely randomized design (CRD) and randomized complete block design (RCBD), respectively. Treatments on yield loss assessment consisted of protected plot, un-protected plot and control plot respectively. Pineapple plants in the protected plots had their suckers dipped for three minutes in a solution of Metalaxyl (Active Ingredients: methoxyacetyl)-N-(2, 6-xylyl)-DLalaninate 8%) before planting and later sprayed with a solution of Fosetyl Al (Active Ingredients: Aluminum trees 80%) using a backpack sprayer with Hardir flat spray nozzles three weeks after planting. Pineapple plants in the un-protected plots were not treated with any fungicide. The suckers were inoculated with 108m1 of zoospores using needle-mediated leaf base wound technique. Treatments on resistance consisted of five cultivars of pineapple (Smooth Cayenne, Victoria, Sasilimu, MD-2 hybrid and Red Spanish) Planted in a field with a history of PHRD infestation. Results from the screen house study indicated100% yield loss in all five cultivars after two months. Field experiments indicate that all the five cultivars used were susceptible to PHRD although Smooth cayenne showed moderate resistance to PHRD. Additional studies, therefore, need to be conducted using more pineapple cultivars to establish their suitability as genetic material in breeding for resistance against PHRD and to minimize yield loss.
Molecular identification and pathogenicity of phytophthora species causing pineapple heart rot disease in Uganda
(Kyambogo University (un published work), 2017-12) Okello, Charles
Pineapple (Ananas cosmosus L.Merrill) has enormous potential for nutritional and health benefits, foreign exchange earnings, industrial growth and development in Uganda. The production of this crop is on the decline, because of outbreak of the pineapple heart rot disease. Therefore the objective of this study was to determine the molecular identity and pathogenicity of the phtophthora causal organism of pineapple heart rot disease. Four major pineapple growing districts in Central Uganda were surveyed for disease prevalence and samples collected for laboratory isolation and characterization between April-May 2016. Twenty one (2 1) sampies of phytophthora heart rot pathogen were isolated from diseased pineapple tissues. Pathogenicity of the pineapple heart rot causal organisms was assessed on invitro pineapple leaves and green apple fruits in laboratory following koch'spostulate. Internal transcribed spacer regions (ITSI, 5.8s !TSUrDNAs, from I I isolates of phy10phthora were analysed by polymerase chain reaction amplification and direct sequencing. The analysis of molecular variance (AMOVA) showed a significant genetic diversity within population (PhiPT= -O.Q68, P= 0.001). Intraspecific variability was detected. The genetic diversity of the population was measured by building phylogeneies based on these sequenced rDNA-ITS data using Muiltiple sequence alignment tool. The results of the pathogenicity test showed that 100% of the isolates were pathogenic apple fruits and healthy pineapple leaves with varying levels of virulence. Based on molecular identification, the sequence of amplified PCR products of DNA fragment of 850bp confined that the causal organism of pineapple heart rot disease was Pnicotianae. AMOVA indicated the variability within populations was (100%). These results also suggest that Pnicotianae has considerable evolutionary potential, which enable it to adapt to the new environment and overcome management strategies over
Yield response of newly released cassava genotypes and hybrid maize to intercropping and inorganic fertilizers in Uganda
(Kyambogo University (un published work), 2019-02) Ekwaro, Benson
This study determined the effect of intercropping the newly developed cassava (Manihot esculenta Crantz) genotypes with hybrid maize (Longe 6H) and NPK fertilizer appljcation on the growth and yield of the component crops. The specific objectives were to determine the effect of maize planting density in the cassava/maize inter crop on the growth and yield of the component crops, and to determine the effect of NPK fertilizer on the growth and yield of the newly released cassava genotypes. In experiment one, two newly released cassava genotypes NAROCASS 1 and NASE 14 inter cropped with Longe 6H maize were evaluated in different combinations including sole maize (SM), sole cassava (SC), one row of maize and cassava ( 1C:1 M), and two rows of maize and cassava (1C:2M). Inter cropping significantly influenced maize plant heights; cob length, the number of rows per cob and the maize grain weight when compared with sole cropping. The cob length and the number of rows per cob decreased in the order SM> 1C:1 M> l C:2M indicating that as the plant population density increases, the cob length and the number of rows per cob gradually decrease. In both NAROCASS I /Maize and NASE 14 /Maize intercrops, maize grain yield under the low plant density (1C:1 M) was comparable to sole cropping than those at the higher plant density (1 C:2M). Thus indicating that increasing maize plant population density (I C:2M) significantly reduced grain yields compared to grain yields at low plant population density (lC:lM). Similarly, cassava root yield decrease in the same order (SM> 1C:1M>1 C:2M) indicating that increased in population gradually reduced root yield. The land equivalent ratio (LER) values for intercrops were greater than one, indicating yield advantage of intercropping over sole cropping. In experiment two, the effects of NPK fertilizer on the growth and yield of the newly released cassava genotypes were assessed at three levels of 200, 400 and 600 kg/ha. Fertilizer application up to 400 kg/ha significantly (P<0.05) influenced the cassava root length, fresh
The role of the smallholder farmer groups on production, processing and marketing of maize: a case study of Hoima district, Uganda
(Kyambogo University, 2019-07) Kasemire, Shamim
Maize farmers in Hoima District have formed groups to overcome the challenges of low production, processing and marketing of maize due to lack of adequate extension support, inadequacy of transport facilities, limited access to inputs and output market. However, studies have shown that even when the farmers form groups, the challenges that farmers face as individuals continue to be experienced in their farmer groups. The challenges listed if left unaddressed, have the potential of causing more decline in maize productivity, incomes and consequently food insecurity. To come up with improved status of maize productivity and marketing among the members of the farmer groups, the study examined the role of farmer groups in production, processing and marketing of maize in Hoima District. The major objective was to examine the role of the participating members and further to establish the challenges faced so that strategies for better performance are suggested. Specifically, the study set out to find out the roles of smallholder farmer groups in production, processing and marketing of maize; identify the factors that enable smallholder farmer groups to improve the marketing of maize produce; and identify the challenges faced by smallholder farmer groups in a bid to uplift output, food security and incomes. A cross sectional survey design was adopted. Data were collected from the members of 4 selected farmer groups, Hoima District Farmers‘ Association and Hoima District Local Government Production and Marketing Officials giving a sample size of 140 respondents. The respondents were selected using simple random and purposive sampling techniques. Questionnaires, interview guide, Observation Guide, Focus Group Discussion guide and Documentary review checklist were used to collect data from the study sites. Qualitative data were presented using narrative text and verbatim quotations. The study findings indicated that to a great extent, the farmer groups have boosted the productivity of maize among farmers. Quantitative data were analyzed using descriptive statistics (percentages and means); inferential statistics were correlation and chi-square tests. Majority of the farmers agreed that their group maize production increased per season to 2 metric tonnes from 1 tonne per individual farmer. Chi- square result shown in Table 4.8 obtained was =19.379 df= 2, p=.000, meaning that there was a significant relationship between membership in farmer‘s group and improved marketing of maize produced. Table 4.5 shows that the correlation coefficient for group factors and maize yield was r= .643* p=0.012<0.05 meaning that there was a positive correlation between farmer group factors and maize yields The group factors that were behind the boost included joint planning, access to better markets because of collective bargaining power, adoption of better and improved maize varieties such as the latest Longe 11 and collaborative relationships with international donor agencies such as Abi-Trust and United States Agency for International Development. These have not only boosted farmer skills through training but have also linked the farmer groups to potential markets. It was also found out the success registered by the farmers was in accessing better markets, improved production and indirect benefits from networking with international organizations. Nevertheless, there were a series of structural and group-based challenges such as poor leadership hampering the effective performance of the farmers groups. The study concluded that farmer groups have boosted maize production in Hoima District. The study recommended the need for provision of extension services to all the farmer groups; need by the government to upgrade the feeder roads in rural areas; and the need for the government to engage monitoring committees at the District and sub county levels to protect the farmers from being cheated by seed dealers and others.
The effect of thermal stress on egg production in layer chickens under deep litter system in House hold
(Kyambogo University, 2019-11) Muntukwonka, Pascal
Despite the presence of a large number of chickens in Uganda, their contribution to the national economy is still limited due to thermal stress, tropical diseases and nutritional limitations. This study carried out in Kibaale, Mid-Western Uganda was therefore meant to assess farmers’ awareness of the effect of Thermal Stress (TS) on egg production, determine the effect of TS on egg production in layers under deep litter system and assess farmers’ acceptability of measures to control TS and its effects. A survey was carried out in the area of study to assess farmers’ awareness of the effect of thermal stress on egg production after which a CRD experiment was conducted on a farmer’s poultry farm in the study area to determine the effect of TS on feed intake, egg production end egg weight. A total of 180 Hy-line brown layers of 24 weeks were randomly assigned to three thermal treatments of 180C, 240C, and 320C for two weeks. The 240C treatment acted as a control set up since it is within the TCZ. Each treatment was replicated 4 times with each replicate having 15 birds. The survey data obtained was analyzed using SPSS while GenStat was used to analyse experimental data. The ANOVA at a significance level of 95%, (0.05) was used. Whereas survey results revealed that most respondents (82%) had no knowledge of the effect of TS on egg production, experimental results showed that temperature treatments significantly (p<0.05) affected feed intake, number of eggs laid an egg weight. At 180C feed intake increased by 9.5% but egg production decreased by 33.3%. At 320C both feed intake and egg production decreased by 20.8% and 40.0% respectively. Farmers’ acceptability to adopt efficient, flexible and recommended methods to control TS was low at only 11.11%. Although both low temperature and high temperature stress depressed egg production and need to be controlled effectively to improve on egg productivity, high temperature stress was more disastrous than low temperature stress. Findings indicate that there is need for an action research which is participatory where selected farmers can be involved in the study under farmer conditions so that they can effectively control thermal stress.
Genetic diversity and resistance to cassava brown streak disease in central Uganda
(Kyambogo University [unpublished work], 2019-11) Ogwal, Sam
Cassava (Manihot esculenta Crantz), a common food security crop in many sub-Saharan African countries is being threatened by cassava brown streak disease (CBSD) which causes up to 100% yield loss in susceptible varieties. Cassava brown streak disease is caused by two distinct Ipomoviruses namely Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV Cassava brown streak disease causes symptoms characterised by chlorotic patches on leaves, dark brown "streaks" on stems, cracked constricted corky, yellow-brown necrotic root tubers of cassava. However, variability of symptoms exists within cassava genotypes and CBSV strains depending on the environmental conditions. Currently in central Uganda, there is limited information on CBSV genetic and symptom diversity, as well as sources of resistance to CBSV. Yet development of CBSD control strategies requires knowledge of CBSV genetic diversity, virus-host interaction and availability of resistant cassava germplasm to CBSD. The objective of this study was therefore to 1) assess genetic diversity and distribution of cassava brown streak disease causal viruses in central Uganda. 21 unravel the symptom diversity of CBSD causal viruses on selected cassava genotypes. 3) identify potential sources of resistance to cassava brown streak disease in central Uganda. Symptomatic leaf samples collected from the four districts in central Uganda were used for total RNA extraction using CT AB protocol. The purified samples were subjected to PCR amplification of specific DNA sequence by in vitro DNA synthesis done as prescribed by Mullis and Faloona (1988). PCR products were separated using electrophoresis and the sequencing of PCR products was done in Netherland at Macrogen laboratory and the sequenced products were edited using Edit Seq in DNA Star, aligned using clustal logarithm MEGA 6 software and coat protein nucleotide sequence data analysed using AMOVA. The results revealed that there was variation in nucleotide sequence and the coat protein among and within CBSV strains with isolates clustering into two groups. Additionally, CBSV was the dominant strain, followed by UCBSV and last mixed infection among 18 out of 20 symptomatic leaves sampled. Symptoms diversity and sources of resistance were identified by inoculating disease free cassava grown in screen house with CBSV strains singly and in combinations using chip bud method of grafting. Symptom diversity was identified based on the dominant symptoms from symptoms appearance at 1 MAI to 3 MAI. For resistance, incidence and severity was assessed. Later severity scores were used to compute area under disease progress curve (AUDPC). Findings showed that there was significant difference (P<0.001) in reaction of cassava genotypes to CBSV viral strains. In addition, significant variety x viral strains interactions (P<0.001) was observed. The highest CBSD incidence and severity was recorded from Kwatampola and the lowest in NASE14. Overall, NASE 14 and NAROCASS were resistant while Aladu, NASE12, Njule, Bam_unanika and Bukalasa were moderately susceptible. Symptom diversity and severity was scored visually from symptom appearance and continued at monthly intervals for three months using a scale of 1 - 5. Findings showed Variation in symptoms of CBSD existed on leaves and stems of cassava genotypes inoculated with CBSV, UCBSV and CBSV+UCBSV strains. Infact, the symptoms varied from chlorotic spots on leaf tips to mild chlorosis, mottling of secondary to primary veins and mild stem streaks. It was concluded that CBSV and UCBSV were dominant strains of CBSV. Additionally genotype NASE 14 was most resistant to CBSD. Accordingly CBSD symptoms varied from chlorotic spots to mild stem streaks. This study has an implication on the management of CBSD in Uganda. However another study to assess the relationship of CBSV viral load, CBSD symptom severity and resistance of cassava genotypes needs to be conducted.
Transmission and diversity of pineapple mealybug wilt disease viruses in Central Uganda
(Kyambogo University(Unpublished work), 2020-07) Mawa, Everrest Michael
Pineapple mealybug wilt disease (PMWD) is one of the latest breakouts of diseases attacking pineapple in Uganda. Although, first reported around 2009, the etiology and epidemiology is not fully elucidated. Pineapple mealybug wilt disease was reportedly devastating in the districts of Mukono and Kayunga with incidence ranging from 15 to 100%, respectively. The causal viruses of PMWD belong to the genus Ampelovirus. However, information on the transmission and diversity of the causal viruses of pineapple mealybug wilt disease in Uganda is limited and scanty. Therefore, this study was undertaken to (1) identify and characterise the diversity of viruses associated with PMWD, (2) determine mealybug action threshold for transmission of PMWD and (3) identify sources of resistance to PMWD. Forty four (44) symptomatic pineapple plant leaves were collected from the districts of Masaka, Luwero, Kayunga and Mukono in central Uganda for laboratory analysis. Molecular analysis using polymerase chain reaction (PCR) was done to identify and assess the diversity of pineapple mealybug wilt disease causal viruses. Total plant RNA was extracted using Cetyltrimethyl ammonium bromide (CTAB), the heat-shock protein 70 homolog (Hsp 70h) gene of causal virus was amplified by RT-PCR using specific primer pair 225/226 for PMWaV-1 and 223/224 for PMWaV-2, respectively. Polymerase chain reaction products were separated by electrophoresis and the resulting amplicons were sequenced using Sanger method. The action threshold for transmission of PMWD was assessed using pineapple variety Smooth cayenne inoculated with five levels of viruliferous mealybugs 0, 1, 5, 10 and 15, respectively. The experiment was arranged in a completely randomised design (CRD) with eight replications. Screening for resistance to PMWD was done on five pineapple varieties (Smooth cayenne, Red Spanish, MD2, Sassilimu and Victoria) inoculated with 15 viruliferous mealybugs. Data was subjected to AMOVA and ANOVA for genetic diversity and action threshold and resistance, respectively. Results showed that only PMWaV-1 was associated with pineapple mealybug wilt disease in central Uganda. Accordingly, high PMWD transmission was recorded in 15 mealybugs. There was significant difference (P˂0.05) in resistance among the pineapple varieties. Red Spanish was highly resistant while Sassilimu, MD2 and Smooth cayenne was moderately resistance and Victoria highly susceptible. The results of this study have therefore shown that only PMWaV-1 was associated with PMWD in central Uganda. The mealybug action threshold for the transmission of PMWD is 15. The study also revealed that the sources of resistance to PMWD are variable although Red Spanish was highly resistant. The implications of these findings therefore is that an effective management strategy against PMWD can be instituted based on the identified and characterized causal virus and action threshold of mealybug as well as the sources of resistance identified. However, there is need for additional studies to unravel genetic diversity using more samples as well as the molecular basis for resistance of pineapple varieties to PMWD.
Field efficacy and economic viability of entomopathogenic fungal products for managing the tomato leafminer (tuta absoluta) in Uganda
(Kyambogo University[unpublished work], 2022-03) Kabaale, Fred Peter
Management of the invasive tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has primarily relied on increased application of hazardous synthetic chemical pesticides with limited success. The use of entomopathogens has been advanced among safer and more sustainable management options. The field efficacy of candidate fungal isolates, Metarhizium anisopliae ICIPE 20, M. anisopliae ICIPE 69 (Campaign®) and Dudu Acelamectin (positive check) was evaluated against T. absoluta on tomato through inundative application. Experiments with treatments laid in Randomised Complete Block Design and replicated thrice, were conducted during cropping seasons April – July, 2019 (first season) and December, 2019 – March, 2020 (second season) at Mukono Zonal Agricultural Research & Development Institute, Mukono district in Uganda. Tuta absoluta incidence, injury severity on leaves and fruits, fruit yield loss, and economic viability of test treatments were assessed. Results showed generally reduced injury severity and significantly lower fruit yield loss in treated plots compared to untreated plot in both seasons. Tomato fruit yield was higher in treated plots than the untreated plot. The marketable fruit yield gain for Dudu Acelamectin, M. anisopliae ICIPE 20 and M. anisopliae ICIPE 69 treatments was respectively 130.15, 72.14 and 55.3% during first season, and 41.21, 22.01 and 15.85% during second season. The three respective treatments had Benefit cost ratio (BCR) of 8.92, 4.31 and 3.43 during first season, and 6.30, 2.84 and 2.14 during second season. The treatments showed a degree of effectiveness and economic viability in controlling T. absoluta on tomato in the field. However, the efficacy of M. anisopliae ICIPE 20 and ICIPE 69 should be assessed further at different agro-ecological zones, dosages, formulations, large scale, and their compatibility with the pesticides commonly used in tomato production systems.
Prevalence and effectiveness of planting time and imidacloprid treated sawdust in control of termites in maize in eastern Uganda
(Kyambogo University [unpublished work], 2022-11) Najjoma, Dennis
Termites are among the most devastating maize pests globally. Quite a lot of research has been conducted on termites in Uganda but information on the incidence of termites and environmentally friendly control measures is scanty, especially in eastern Uganda. Accordingly, the farmers are reported to use several chemical and cultural methods for managing termites, most of them not very sustainable and quite expensive in the long run. Therefore, this study was conducted with two key objectives, i) to ascertain the prevalence and diversity of termites in eastern Uganda and, ii) determine the effect of integrating planting time and treated wood sawdust in control of termites. Termite prevalence was determined by collecting data using a questionnaire and interview from 272 respondents in the nine districts in Eastern Uganda. For objective two, three experiments were laid out at lkulwe Satellite Station in Mayuge District in a Randomized Complete Block Design (RCBD) with four treatments, namely (i) Wood sawdust treated with imidacloprid (IM+WSD), (ii) Wood Sawdust only (WSD), (iii) Imidacloprid only (IM) and (iv) the Control (no treatment). The data was collected on the number of lodged plants, termite number and grain yield, among other parameters. Data was subjected to analysis of variance using Genstat (15th Edition) statistical software. Results showed that the highest (95.5%) termite prevalence was in Kapchorwa and the lowest in Pallisa and Bugiri, each recording 44.2%. The dominant (65.5%) termite species was Macrotermes bellcosus. Imidacloprid treated wood sawdust and early planting significantly (P<0.05) reduced termite's infestation. Imidacloprid treated wood sawdust had generally low termite population (442 and 759 termites/ha) compared to the control (2154 and 2840 termites/ha) under early and late planting, respectively. Low number of damaged cobs and high yield was recorded under early planting and treated saw dust. It can be concluded that use of treated sawdust as bait to control termite damage and early planting of maize will increase grain yield. However, there is need for additional studies in different agro-ecological zones to validate the results on use of treated wood sawdust and early planting.
Influence of agro-ecological zone on azadirachtin concentration and efficacy of neem leaf powder against sitophilus zeamais in Uganda
(Kyambogo University [unpublished work], 2023-10) Muleni, Joseph
Using synthetic insecticides to control Sitophilus zeamais has raised serious concern on the environment and human health. There is need to adopt a more affordable and eco-friendly option such as neem bio pesticide. Neem is reported to contain AZA active ingredient with insecticidal properties against S.zeamais. Neem leaf powders obtained from four AEZs were evaluated for AZA cone. and efficacy against S.zeamais. Extraction of AZA in neem leaf powders was done in two replicates using 100g of fine powder each obtained from the four AEZ while quantification was done using HPLC. Efficacy of neem leaf powder against S.zeamais was assessed using four doses: 0.5, 1.0, 1.5 and 2.0g. There were significant differences in cone. of AZA in neem leaf powders from the 4 different AEZs. Lake Victoria Crescent which experiences moderate climate with average rainfall had the highest AZA content (35.23 mg/g) while Karamoja dry land with hot climate had the lowest AZA (27.76 mg/g). Further, maize grain treated with neem leaf powders obtained from Lake Victoria Crescent with the highest cone. of AZA had the lowest mean weevil count (13/100g) with lowest mean number of damaged grains (4.8 /100g) while Karamoja dry land with the lowest AZA cone had the highest mean weevil number (25 /100gm) and the highest mean number of damaged maize grains (11. 7/100g). Neem leaf powder dosage of 2.0g effectively reduced the mean grain damage to I 0.0 compared to 20.0 when treated with 0.5g. When using neem leaf powder as an option, customized quantities should be used basing on the AEZ from which the neem leaf product is obtained and those using neem products from Karamoja dry land, should use more quantities compared to Lake Victoria Crescent AEZ.

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