Browsing by Author "Christopher, Faustine"

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    Antifungal Activities of Some Medicinal Plants Against Colletotrichum lindemuthianum, the Causal Pathogen of Bean Anthracnose, and their Effect on Seed Germination and Seedling Performance
    (Centre for Advancement of Applied Sciences, 2022-12-12) Christopher, Faustine; Ndakidemi, Patrick; Nyalala, Samuel; Mbega, Ernest
    This study evaluated the in vitro potency of Plectranthus barbatus, Vernonia amygdalina, Conyza bonariensis, Leonotis nepetifolia, and Lantana camara extracts against Colletotrichum lindemuthianum, the causal pathogen of anthracnose in common bean (Phaseolus vulgaris), as well as assessed their effect on seed germination and seedling performance under greenhouse conditions. In vitro assessment of antifungal activities of extracts was carried out using the poisoned food technique. Ethyl acetate extract of C. bonariensis was found most effective against the pathogen and completely inhibited its growth at 5.0, 2.5, and 1.25 mg mL-1 while it showed 91.2% inhibition at 0.5 mg mL-1 level. This was followed by P. barbatus and L. nepetifolia which completely inhibited the growth at 5.0 and 2.5 mg mL-1 level. Methanolic extracts were also effective with highest inhibition observed for L. camara (85.1%) at 5.0 mg mL-1, followed by P. barbatus (84.7%) and L. nepetifolia (83.1%) at the same concentration. Similarly, the aqueous extracts showed remarkable inhibition at the highest concentrations tested. Aqueous extracts of L. nepetifolia, V. amygdalina, and C. bonariensis inflicted maximum inhibition at 5.0 mg mL-1 (75.0, 74.7, and 73.3%, respectively). Extracts had no adverse effect on seed germination and seedling performance, but the test fungicide reduced seed germination significantly (p < 0.001). Easy accessibility of the studied medicinal plants and their potential in managing bean anthracnose provides an opportunity to use such plant extracts as seed dressers to manage bean anthracnose in smallholder farmers in Tanzania.
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    Antifungal activity of Leonotis nepetifolia extracts against Colletotrichum species causing bean anthracnose and their phytochemical analysis using LC-MS
    (Elsevier B.V., 2023-08-30) Christopher, Faustine; Ndakidemi, Patrick; Nyalala, Samuel; Mbega, Ernest
    Bean anthracnose results in significant yield losses, and the present primary management strategy of using synthetic fungicides is hampered by a number of factors. This study assessed the antifungal effects of aqueous, methanolic, and ethyl acetate extracts of Leonotis nepetifolia (Lamiaceae) against Colletotrichum species that cause bean anthracnose. The poisoned food technique was used to evaluate extracts in-vitro, and trials were carried out on farmer's plots. On the other hand, phytochemical analysis was done using LC-MS. Results obtained in-vitro show that the ethyl acetate extract was the most effective since it completely inhibited mycelial development at concentrations of 5 mg/mL and 2.5 mg/mL. On the other hand, the aqueous and methanolic extracts exhibited a comparable inhibitory effect, and at the higher concentration (5.0 mg/mL), a remarkable percentage of inhibition of 73.3% and 83.1% was recorded. According to field trials, bean anthracnose incidence was low and there were fewer infected pods per plant in plots treated with L. nepetifolia extracts than in the negative control. In comparison to the negative control plots, extracts-treated plots had larger weights of 100 seeds but no discernible negative effect in seed germination. LC-MS analysis indicated the presence of Linoleoyl ethanolamide, Curcumol, Deguelin, 9,10-dihydroxy-12Z-octadecenoic acid, Naringenin-7-O-glucoside, and 9S-hydroxy-10e 12z 15z-octadecatrienoic acid in the ethyl acetate extract whereas 6-Methoxyluteolin, Genistein, 5,7,3,4-tetramethoxyisoflavone, and 3,4-Dihydroxymandelic acid were identified in the aqueous extract. Antifungal activity and the presence of bioactive components revealed by extracts in this study demonstrate the potential of L. nepetifolia as a source of botanical fungicide for the management of bean anthracnose.