Browsing by Author "Ganiyu Shittu Olahan"

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    Bioefficacy of leaf extracts of Azadirachta indica and vernonia amygdalina and their mixture against Colletotrichum falcatum
    (West University of Timisoara, series Biology., 2020-01-17) Ganiyu Shittu Olahan; Paul Ojo Fatoba; Oluwasegun Samuel Balogun
    Chemical control of red rot disease of sugarcane with synthetic fungicides, though effective, enables the pathogen to produce new pathological races or strains that are resistant to the available synthetic fungicides in the market. The synthetic fungicides, in addition, have harmful side effects on humans, other animals and the environment. This study evaluated the in vitro antifungal activity of leaf extracts of Azadirachta indica and Vernonia amygdalina against Colletotrichum falcatum, the pathogen of red rot disease of sugarcane. Pour Plate method was used to determine the effect of 10, 20 and 30 g/100 ml concentrations of aqueous and ethanolic leaf extracts of A. indica and V. amygdalina and their integration on mycelial radial growth of C. falcatum. The aqueous and ethanolic leaf extracts of the botanical species and their integrated leaf extracts inhibited the mycelial growth of C. falcatum in vitro, with the ethanolic extracts being more potent at some of the concentrations tested against the pathogens. The gradient of efficacy of the 3 types of leaf extracts tested for antifungal efficacy against C. falcatum was: mixed leaf extracts leaf> neem leaf extracts> bitterleaf leaf extracts, regardless of the extractant at all the concentrations used in this study.
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    Fungicidal effect of teak (Tectona grandis L.) extracts on Fusarium oxysporum
    (West University of Timisoara, series of Biology., 2023-12-29) Ganiyu Shittu Olahan; Ibrahim Ajadi; Patience Olayinka Ben-Uwabor
    Fusarium oxysporum f. sp. lycopersici is the pathogen of tomato wilt, a disease of great economic importance worldwide. Although application of synthetic fungicides such as thiophanate methyl and mancozeb can prevent the occurrence of this disease, their effects on the physical environment especially, is a limiting factor. Botanicals, i.e. plantbased fungicides are now being preffered for controlling fungal pathogens because they have minimal environmental impact and are less dangerous to consumers in contrast to synthetic fungicides. Teak leaves have been reported to possess a very great antimicrobial activity because of their high content of phytochemicals. In an effort to develop eco-friendly chemical strategy for control of Fusarium wilt disease of tomato plants, in vitro effect of 10, 30 and 50% (w/v) concentrations of the aqueous and ethanolic leaf extracts of teak (Tectona grandis L.) on the radial growth of the mycelia of Fusarium oxysporum f. sp. lycopersici was investigated using the pour plate method. Results of the study revealed that both extracts retarded the radial growth of mycelia of F. oxysporum f. sp. lycopersici compared to that of the control, with the ethanolic extract having a greater effect at the concentrations tested in this study. It is therefore recommended that an in vivo study of effects of the same leaf extracts on wilt – infected tomato plants be conducted.
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    Microbial load and molecular chracterization of fungi associated with sweet pepper (Capsicum annuum L.) during storage
    (Published by Institute of Biology, Romanian Academy, 2022) Taofeeq Garuba; Babatunde Yusuf Lawal; Azeez Adebola Lateef; Ganiyu Shittu Olahan
    Peppers are perishable and characterized with a short shelf life. Poor storage methods contribute immensely to their deterioration, leading to a great postharvest loss. This study is therefore aimed at isolation and characterization of fungi causing spoilage in sweet pepper during storage. Some healthy samples of Capsicum annuum fruits were collected from Lasoju farm located in Asa LGA of Kwara State, Nigeria in sterile polyethylene bags and transported to the laboratory. The fruits were kept in the refrigerator, at ambient condition and in an evaporative cooling system. The fruits were observed for spoilage at the end of the second and third week after storage. The spoiled samples were sterilized, cultured on Potato Dextrose Agar, incubated at 25 C for 3–28 days. Thereafter, the different fungal colonies resulted were sub-cultured to obtain pure cultures of each of them. It was revealed that polythene bag as storage material for Capsicum annuum promoted increase in microbial load, while the pure fungal isolates were identified morphologically and molecularly as Aspergillus fumigatus, A. flavus and Rhizopus oryzae. Therefore, the fresh fruits need to be properly handled and stored in order to eliminate or minimize fungal contamination.