Browsing by Author "Ogolla O. F."

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    Evaluation of Tomato Early Blight Pathogens’ Characteristics and Susceptibility of Locally Grown Tomato Varieties to Early Blight Infection in Kirinyaga County, Kenya
    (Chuka University, 2023) Ogolla O. F.; Muraya M. M.; Onyango O. B.
    Tomato (Lycopersicon esculentum Mill) is a highly consumed and produced vegetable crop with an annual global production of over 185 million tonnes, due to its nutritional and health benefits. However, tomato production is characterized by inconsistent quality and yields partly emanating from biotic constraints attributed to fungal foliar diseases. In Kirinyaga County, where tomato production is a significant source of livelihoods, there exists knowledge gap on the identity of pathogens causing early blight in different Agro-ecological zones (AEZs) and on the susceptibility of locally grown tomato varieties to the infection. The objective of this study was to determine the characteristics of early blight pathogen isolated from tomato leaves collected from different AEZs and assess the susceptibility level of some tomato varieties grown in Kirinyaga County to the early blight pathogens isolates. Pathogen characterization was carried out using morphological and molecular approaches while susceptibility of tomato varieties to fungal pathogens was evaluated by artificial inoculation. Molecular characterization for fungal pathogen involved BLASTIN analysis of DNA amplicon Sanger sequenced nucleotides and use of NCBI databases. The susceptibility assay was carried out in the greenhouse using a completely randomised design (CRD). Data on the fungal conidia lengths (µm) were subjected to Analysis of Variance (ANOVA) and significant means separated by Least Significance Difference (LSD) at α = 0.05. Data on the susceptibility (%) of tomato varieties to fungal pathogens isolates was subjected to ANOVA and significance means separated using LSD at α = 0.05. Morphologies of early blight pathogen pathogens differed significantly (p < 0.05) with conidia lengths from 52.8 and 204.20µm. Molecular characterization of some selected culture implicated Alternaria solani and A. alternate involvement in causing early blight. Tomato varieties differed in their susceptibility to early blight pathogens (p < 0.05). Kilele F1 was the most susceptible variety (73.84%) while Terminator F1 was least susceptible (56.48%) to early blight pathogens. It can be concluded that Terminator F1 was the least susceptible among tomato variety cultivated by farmers in Kirinyaga County and can serve as source for genetic improvement of tomato varieties for Kirinyaga pathosystem.
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    A REVIEW OF BACTERIAL PATHOGENS FOUND IN RAW MILK AND THEIR HEALTH SIGNIFICANCE
    (Chuka University, 2022) Atieno, M. F.; Ogolla O. F.; Nyakinywa, R.
    Raw milk has benefits such as maintenance of healthy bones due to the combination of nutrients helping prevent diseases such as osteoporosis, high protein content in milk making people full for a longer period of time thus reducing obesity, nutritional benefits due to the presence of nutrients, beneficial microflora and antibacterial systems and protection against the development of allergies. Milk is composed of water, fat, protein, lactose, enzymes, minerals and vitamins in different proportions. Milk is an excellent culture and protective medium thereby creating a conducive environment for pathogenic bacteria such as Salmonella, E. coli, Campylobacter spp, Staphylococcus aureus, Streptococcus spp and Listeria to thrive in. Thus, intake of raw milk has been associated with health complications such as typhoid fever, infantile gastroenteritis, campylobacteriosis, pneumonia, listeriosis and food poisoning. Pathogens contaminate milk through infested cattle faeces, udder, handler and utensil, mastitic milk and infertility as in the case of listeriosis. Thus, the objective of this paper was to review on bacteria pathogens associated with raw milk and their health significance. Salmonella has two species but only S. enterica is pathogenic and causes salmonellosis with nausea, vomiting, abdominal cramps, diarrhea, fever, chills, headache and blood in the stool as its symptoms. Pathogenic E. coli are of six types causing infertile gastroenteritis, hemolytic and uremic syndrome associated with symptoms of severe intestinal and extra intestinal diseases, diarrhea, abdominal cramp and vomiting. Streptococcus has S. pneumoniae, S. pyogenes and S. agalactiae as the pathogenic species causing pneumonia, sore throat and scarlet fever. Campylobacter has seven pathogenic species but only Campylobacter jejuni and Campylobacter coli are the most common pathogens causing campylobacteriosis. Staphylococcus aureus is the main bacteria responsible for causing foodborne poisoning in human due to its production of exotoxins. Listeria has L. monocytogenes and L. ivanovii as the pathogenic species responsible for septicemia, circling disease, encephalitis, abortion and still births. Proper handling of milk may alleviate health complications associated with pathogens contaminants. Practices such as pasteurization and sterilization of equipment are necessary to ensure milk safety.